Information

 

Definitions of Diseases

 

The information on this page is intended to assist South African Veterinary Services in disease control and surveillance activities and should not be referenced as a scientific source. The Merck Veterinary Manual (8th Edition and older) and information from the World Organisation for Animal Health (OIE) (www.oie.int) was used to compile this information.

A010 Foot-and-mouth disease (FMD)

An acute,  highly contagious, viral infection of domestic and wild cloven-hooved animals. Morbidity and mortality are highest in the young. Initially, it is characterized by vesicular lesions; subsequently, by erosions of the epithelium of the mouth, nares, muzzle, feet, teats, udder, and rumen pillars. The natural hosts are cattle, pigs, sheep, goats, water buffalo, bison, deer, antelope, wild pigs, reindeer, llamas, chamois, alpacas, vicunas, giraffes, elephants, elk, camels, capybaras, moles, voles, rats, and hedgehogs. Experimentally, FMD virus (FMDV) may be transmitted to mice, guinea pigs, rabbits, hamsters, embryonating chicken eggs, chickens, chinchillas, muskrats, grizzly bears, armadillos, and peccaries. Horses are resistant. The virus will replicate when inoculated into monkeys, turtles, frogs, and snakes, but these species do not normally develop lesions. FMD is endemic in Asia, Africa, parts of Europe, and most of South America. North and Central America, the Caribbean, Australia, New Zealand, and many of the islands of Oceania are free of FMD. Great Britain and many other western European countries, such as Denmark, Norway, and Sweden, are free most of the time. Ireland has been free since 1941, and it has not occurred in Japan for decades.

Etiology: FMD is caused by an enterovirus of the family Picornaviridae. At least 7 immunologically distinct types of FMDV have been identified by complement fixation as A; O; C; South African Territories (SAT) 1, 2, 3; and Asia 1.

A011 FMD - Virus O (see A010)

A012 FMD - Virus A (see A010)

A013 FMD - Virus C (see A010)

A014 FMD - Virus SAT 1 (see A010)

A015 FMD - Virus SAT 2 (see A010)

A016 FMD - Virus SAT 3 (see A010)

A017 FMD - Virus Asia 1 (see A010)

A018 FMD - Virus not typed (see A010)

A020 Vesicular stomatitis (VS)

A viral disease characterized by fever and vesicles on the mucous membranes of the mouth, epithelium of the tongue, teats, soles of the feet, coronary band, and occasionally other parts of the body. Cattle, horses, and pigs are naturally susceptible; sheep and goats are infected occasionally. The agents have a wide host range, including deer, bobcats, raccoons, and monkeys; many rodents and cold- blooded animals have been infected experimentally. An influenza-like disease has occurred in people working with affected animals or the virus. Vesicular stomatitis has been confirmed only in North and South America. The rod-shaped viruses belong to the rhabdovirus group, members of which infect not only mammals, but also fish, insects, and plants a diversity of hosts unknown for any other group of viruses. There are 2 distinct serotypes: the New Jersey and Indiana, with 3 subtypes of the latter.

A021 VS - Virus Indiana (see A020)

A022 VS - Virus New Jersey (see A020)

A023 VS - Virus not typed (see A020)

A030 Swine vesicular disease

Typically, a transient disease of pigs in which vesicular lesions appear in the mouth and on the feet. The lesions are similar to those of foot-and-mouth disease, vesicular exanthema of swine, and vesicular stomatitis, but the pig does not lose condition, and the lesions heal rapidly. Nervous signs have been described but rarely observed in the field. The disease does not cause severe production losses but is of major economic importance because it must be differentiated from FMD, eradication is costly, and embargoes on pork are often imposed on nations not free of SVD. Although infection in laboratory workers has occurred, and the virus may be present in sheep or cattle, pigs are said to be the only natural host.

A040 Rinderpest

(Cattle plague)

A disease of cloven-hoofed animals characterized by fever, necrotic stomatitis, gastroenteritis, lymphoid necrosis, and high mortality. In epidemic form, it is the most lethal plague known in cattle. Susceptibility varies among species: it is high in African buffalo, giraffes, wild Suidae, Tragelaphinae, and breeds of cattle such as Ankole, Channel Islands, and Japanese Black; moderate in wildebeest and East African zebus; and mild in gazelles and small domestic ruminants. Rinderpest is subclinical in European pigs and hippopotami. It is endemic in India and Africa. Lack of control in bordering countries has recently led to epidemics in west, east, and north Africa; the Near East; and parts of Asia. The infectious agent is a morbillivirus, closely related to the viruses of peste des petits ruminants, canine distemper, and measles. Strains of virus vary markedly in host range and virulence.

A050 Peste des petits ruminants

PPR is also known as pseudorinderpest of small ruminants, pest of small ruminants, pest of sheep and goats, Kata, stomatitis-pneumoenteritis syndrome, contagious pustular stomatitis, and pneumoenteritis complex. It is an acute or subcute viral disease of goats and sheep characterized by fever, necrotic stomatitis, gastroenteritis, and pneumonia. It was first reported as a clinical entity in the Ivory Coast in 1942, and subsequently in Senegal,

Ghana, Togo, Benin, and Nigeria. Sheep are less susceptible than goats; cattle are only subclinically infected. Man is not at risk. The causal virus, a morbillivirus of the family Paramyxoviridae, has a particular affinity for lymphoid tissues and epithelial tissue of the GI tract, in which it produces characteristic lesions. PPR is prevalent in West and Central Africa and the Middle East.

A060 Contagious bovine pleuropneumonia

A highly contagious pneumonia generally accompanied by pleurisy. It is present in Africa, the Iberian peninsula, and parts of India and China; minor outbreaks occur in the Middle East. The USA has been free of the disease since 1892, the UK since 1898, and Australia since 1973. Etiology: The causal organism is Mycoplasma mycoides mycoides.

A070 Lumpy skin disease

An infectious, eruptive, occasionally fatal disease of cattle characterized by nodules on the skin and other parts of the body. Secondary infection often aggravates the condition. Traditionally, it occurs in southern and eastern Africa, but in recent years has extended northwest through the continent into sub-Saharan West Africa. The causal virus is related to that of sheeppox. The prototype strain is known as the Neethling poxvirus.

A080 Rift Valley fever

(Infectious enzootic hepatitis of sheep and cattle)

A mosquito-borne viral disease of animals, including man, characterized by a short incubation period, fever, hepatitis, abortion, and death in young animals. Most domestic animals are affected except for pigs, guinea pigs, rabbits, and chickens. Young lambs, kids, calves, and puppies are highly susceptible. Sheep and man are more susceptible than cattle and dogs. Significant morbidity and mortality occur in sheep, cattle, and man. The disease has been diagnosed in many African countries; recent outbreaks have occurred in Egypt, Senegal, and Mauritania. The causal agent is a phlebovirus of the family Bunyaviridae.

A090 Bluetongue

A noncontagious, insect-transmitted, viral disease of sheep, cattle, goats, and wild ruminants. The disease occurs widely on the African continent and to a lesser extent in North America, Asia, and Europe. The virus has been isolated from biting insects (Culicoides spp) and cattle in Australia; however, there is no clinical evidence that bluetongue disease exists in ruminants on that continent. Serological evidence of widespread infection in ruminants in the Caribbean and some countries in South and Central America exists, but clinical disease has not been confirmed. Bluetongue virus is an orbivirus, family Reoviridae; 24 antigenic serotypes have been identified in the world, 5 in the USA. Under natural conditions, the virus is biologically transmitted by Culicoides spp. Cattle are an important reservoir for sheep and other susceptible ruminants; some wild ruminant species also may be reservoirs.

A100 Sheep pox and goat pox

Serious, often fatal, diseases characterized by widespread skin eruption. Both diseases are confined to parts of southeastern Europe, Africa, and Asia. The poxviruses of sheep and goats (capripoxviruses) are closely related, both antigenically and physicochemically. They are also related to the virus of lumpy skin disease (see above). Reports on the natural susceptibility of sheep to goat poxvirus and vice versa are conflicting; at least some strains seem capable of infecting both species.

A110 African horse sickness

An acute or subacute, insect-borne, viral disease of Equidae, endemic to the African continent, and characterized by clinical signs and lesions associated with respiratory and circulatory impairment. AHS is caused by an orbivirus of the family Reoviridae. There are 9 immunologically distinct types.

A120 African swine fever

A highly contagious viral disease with signs and lesions resembling those of hog cholera. Before 1957, it was restricted to Africa and appeared as a highly virulent infection of domestic pigs in contact with endogenous wild pigs. The warthog, bushpig, and giant forest hog are frequently infected, inapparent carriers of the virus. The first extensions of ASF outside Africa occurred in Portugal in 1957 and in Spain in 1960. There were numerous outbreaks in France and Italy over the next 20 yr; it spread to the Caribbean and South America in the 1970's, and to Belgium and Holland in the 1980's. In contrast to the severe clinical manifestations of the African isolates, less virulent forms emerged during epidemics on the Iberian peninsula, which has made the clinical diagnosis much more difficult. It has been eradicated from the Western Hemisphere but continues to exist in domestic pigs in Portugal and Spain, and in wild pigs on Sardinia and in several countries in Africa. Although ASF virus is classified as an iridovirus, it has some properties of poxviruses.

A130 Hog cholera

(Swine fever, Classical swine fever)

A highly contagious viral disease of pigs. Disease due to virulent viral strains has a sudden onset, and affects pigs of all ages with high morbidity and mortality, although adults are least affected. Less virulent strains cause chronic or mild disease, reproductive failure, and neonatal losses. Inapparent infection can also occur. Hog cholera is endemic in many South American, African, and Asian countries. It is absent from Canada, Australia, and New Zealand, and has been eradicated from the USA and a number of European countries. The cause is a pestivirus, family Togaviridae.

A150 Fowl plague

(Influenza)

A viral disease of domestic and wild birds with signs ranging from almost no clinical disease to high mortality. The incubation period also is highly variable, and ranges from a few days to 1 wk. The causal orthomyxoviruses are type A influenza viruses. Both virulent and avirulent viruses with any of 13 known surface hemagglutinins are known to infect avian species.

A160 Newcastle disease

(Avian pneumoencephalitis)

An acute, rapidly spreading, viral disease of domestic poultry and other birds worldwide, characterized by rapid onset and variable mortality. Respiratory signs (coughing, sneezing, rales) are often accompanied or followed by nervous manifestations and, in infections with some strains, by diarrhea and swelling of the head. Although Newcastle disease virus can produce a transitory conjunctivitis in man, the condition has been limited primarily to laboratory workers and vaccination teams exposed to large quantities of virus and, before vaccination was widely practiced, to crews eviscerating poultry in processing plants. The disease has not been reported in individuals who rear poultry or consume poultry products. The cause is an RNA virus, paramyxovirus-1 (PMV-1), which can be categorized into 3 groups: the velogenic strains are highly pathogenic and easily transmitted, the mesogenic strains are intermediate, and the lentogenic strains show low pathogenicity in chickens.

B051 Anthrax

(Splenic fever, Charbon, Milzbrand)

An acute, febrile disease of virtually all warm-blooded animals, including man, caused by Bacillus anthracis. Most commonly, it is a septicemia characterized principally by a rapidly fatal course. It occurs worldwide, and is irregularly distributed in districts where repeated outbreaks occur. Bacillus anthracis is a gram-positive, nonmotile, spore-forming bacterium. After discharge from an infected animal or when bacilli from an opened carcass are exposed to free oxygen, they form spores that are resistant to extremes of temperature, chemical disinfectants, and desiccation. For this reason, the carcass of an animal dead of anthrax should not be necropsied.

B052 Aujeszky's disease

(Pseudorabies, Mad itch)

A viral infection, primarily of pigs, that affects the CNS. The host range is broad, although the infection is fatal in virtually all animals that become infected except pigs. Man, apes, chimpanzees, poikilotherms, and insects are resistant to infection. The virus can survive on the body surface of domestic flies, which may serve as a source of virus. Pseudorabies has been reported in the USA, Central and South America, Europe, India, Southeast Asia, Taiwan, Japan, northern countries of Africa, and New Zealand. It has not been detected in Canada or Australia. The causal herpesvirus has a double strand of DNA and a lipoprotein envelope. There are at least 5 glycoproteins that project from the envelope. Virus persists in a latent state in ganglion neurons in a high percentage of infected pigs. Many strains of virus exist and vary from apparent avirulence for pigs to highly virulent.

B053 Echinococcosis/Hydatidosis

Disease: Echinococcosis, Hydatid disease

Causative organism: Echinococcus granulosus

Principal animals involved: Dogs, wild carnivores, sheep, cattle

Known distribution: Worldwide

Probable means of spread to man: Ingestion of eggs shed in feces of carnivores.

Disease: Echinococcosis, Hydatid disease

Causative organism: Echinococcus multilocularis

Principal animals involved: Canidae, domestic cats, small rodents

Known distribution: Northern Hemisphere

Probable means of spread to man: Ingestion of eggs shed in feces of carnivores.

B055 Heartwater

An infectious, noncontagious, rickettsial disease of ruminants in areas infested by ticks of the genus Amblyomma, which include regions of Africa south of the Sahara, and the islands of Madagascar, Reunion, Mauritius, and the Caribbean. Many ruminants, including antelopes, are susceptible; others, such as the blesbok and wildebeest become subclinically infected and may act as reservoirs. Bos indicus indigenous breeds of cattle appear more resistant than imported breeds. The causative organism, Cowdria ruminantium, an obligate intracellular parasite, is transmitted under natural conditions by "bont" ticks belonging to the genus Amblyomma. These 3-host ticks become infected during either larval or nymphal stages and transmit the infection during one of the subsequent stages. The progeny of an infected female tick are not infective.

B056 Leptospirosis

A contagious disease of animals, including man, caused by infection with various immunologically distinct leptospiral serovars, most of which are regarded as subgroups of Leptospira interrogans. Infections may be asymptomatic or result in various disease conditions, including fever, icterus, hemoglobinuria, infertility, abortion, and death. Following acute infection, leptospires frequently localize in the kidneys or reproductive organs and are shed in the urine, sometimes in large numbers for months or years. The disease is often water-borne, since the organisms survive in surface waters for extended periods.

B057 Q-fever

A rickettsial infection, usually inapparent, but able to cause abortion in sheep, goats, and cattle, and an influenza-like disease in man that may result in chronic endocarditis. The risk of infection is greatly increased for people (veterinarians, livestockmen, abattoir workers, and laboratory personnel) in occupations that bring them in direct or indirect contact with infected, parturient sheep, goats, or cattle, or with products (wool or hides) of infected animals. Several episodes of Q-fever have occurred in personnel and human patients in medical institutions where latently infected sheep were used for research. Human infection apparently was acquired by inhalation of airborne infectious agents. The causative organism, Coxiella burnetii, is distributed worldwide and has been found in various wild and domestic mammals, arthropods, and birds. Domestic cattle, sheep, goats, dogs, and cats are susceptible to infection, and the disease is found in most areas where cattle, sheep, and goats are kept. Ixodid and argasid ticks can be reservoirs of the organism.

B058 Rabies

An acute, viral encephalomyelitis that affects all warm-blooded animals. The mortality rate is close to 100%. Although rabies occurs throughout the world, a few countries are free of the disease due to successful eradication programs, or by virtue of their island status or enforcing rigorous quarantine regulations. Of the 4 lyssavirus serotypes currently recognized, serotype 1 is responsible for classical terrestrial animal rabies. Serotypes 2, 3, and 4 are rabies-related viruses that have antigenic and epidemiological differences from rabies proper. Rabies viruses recently identified in European bats are currently classified as serotype 4. The predominant animal species in which rabies is maintained varies in different parts of the world. Dog rabies predominates in Africa, Asia, Latin America, and the Middle East.

B059 Paratuberculosis

(Johne's Disease)

A chronic, contagious enteritis characterized by persistent and progressive diarrhea, weight loss, debilitation, and eventually, death. It affects cattle, sheep, goats, llamas, camels, farmed deer, and other domestic and wild ruminants. Distribution is worldwide. The zoonotic risk has been considered minimal, but the isolation of similar organisms from some people with Crohn's enteritis makes this less certain. Etiology: Mycobacterium paratuberculosis (johnei).

B060 Screwworm (Cochliomyia hominivorax)

Screwworms are larvae of the blowfly, Cochliomyia (Callitroga) hominivorax (order Diptera, family Calliphoridae), which is an obligate myiasis-causing parasite. The female screwworm fly lays eggs on wounds, cuts, bites, navels of newborns, and other sites in the skin of all warm-blooded animals. Cochliomyia hominivorax is distributed throughout the neoarctic and neotropical regions of the Western Hemisphere. As a result of massive state, federal, and international eradication programs, extant populations of C hominivorax are no longer found in the USA or Mexico; the isolated reports of infestations are often traced to importation of infested animals from locations where the screwworm is still prevalent. Extant populations are found in Central and South America, and certain Caribbean islands. Another species of screwworm, the "old world" screwworm, Chrysomyia bezziana, is found in Africa and southern Asia, including Papua New Guinea.

B070 Nagana (trypanosomiasis)

(Tsetse-transmitted trypanosomiasis)

A group of diseases caused by protozoa of the genus Trypanosoma,which affect all domestic animals. The major species are T congolense, T vivax, T brucei, and T simiae. In order of importance, those affecting cattle, sheep, and goats are T congolense, T vivax, and T brucei. In pigs, T simiae is the most important. In dogs and cats, T brucei is probably the most important. It is difficult to assign an order of importance for horses and camels. The trypanosomes that cause tsetse-transmitted trypanosomiasis (sleeping sickness) in man, T rhodesiense and T gambiense, closely resemble T brucei from animals.

B071 Salmonella Enteritidis

 

 

B101 Anaplasmosis

A peracute to chronic infectious disease of ruminants, characterized chiefly by anemia, icterus, and fever. It is often endemic in the tropics and subtropics, notably in the Americas and Africa, but also is prevalent in Australia, the South Pacific Islands, and southern Asia. In the USA it has been reported from all the contiguous states, but is most prevalent in the southeast, the intermountain west, and California. The causative rickettsial agent, Anaplasma marginale, is a small, spherical body without cytoplasm, and is located in the stroma of the RBC. Multiplication appears to be by binary fission within a vacuole, which results in 2 or more initial bodies within inclusions that tend to be found near the margin of the RBC. Anaplasma centrale, which is more centrally located in the RBC, is a relatively nonpathogenic species found in cattle in some regions of Africa; another species, A ovis, occurs in sheep and goats worldwide, and may cause disease in stressful situations. Anaplasma spp infections also occur in various wild ungulates such as deer and antelope; their importance as reservoir hosts has not been clearly established.

B102 Babesiosis (Redwater)

A group of tick-borne diseases caused by protozoa of the genus Babesia. Babesiosis is a significant problem in domestic and wild animals wherever suitable tick vectors occur, especially in the tropics. The most important economic losses are caused in cattle by B bovis and B bigemina, acting either singly or together in the same group of animals. Since these 2 species share tick vectors with Anaplasma marginale (see above), some or all of them can combine to produce a fatal syndrome known as tick fever. To a large extent, the major Babesia spp are both host and vector specific. Thus, B bovis and B bigemina are found exclusively in cattle, and their distribution coincides with that of their major tick vectors, Boophilus spp. Certain other ticks can act as vectors, and mechanical transmission by biting flies can occur.

B103 Bovine brucellosis (Brucella abortus)

(Contagious abortion, Bang's disease)

The disease in cattle is caused almost exclusively by Brucella abortus; however, B suis or B melitensis is occasionally implicated. Infection spreads rapidly and causes many abortions in unvaccinated herds. Typically, in a herd in which disease is endemic, an infected cow aborts only once after exposure; subsequent gestations and lactations appear normal. Following exposure, many cattle become bacteremic for a short period and develop agglutinins and other antibodies; most of the remainder resist infection, and a small percentage of infected cows recover.

B104 Bovine genital campylobacteriosis

A venereal disease of cattle characterized by infertility and early embryonic death. Abortion occurs in a small percentage of infected cows. Distribution is worldwide. Campylobacter fetus subsp venerealis, the usual cause of this disease, is a gram-negative, curved or spiral-shaped rod, which is motile by means of a polar flagellum.

B105 Bovine tuberculosis (Mycobacterium bovis)

An infectious disease caused by acid-fast bacilli of the genus Mycobacterium. Although commonly defined as a chronic, debilitating disease, TB occasionally assumes an acute, rapidly progressive course. The disease affects practically all species of vertebrates, and before control measures were adopted, was a major disease of man and domestic animals. Signs and lesions are generally similar in the various species.

Once widespread, particularly in dairy cattle, control programs have so reduced the incidence that several countries have virtually eliminated it. The source of infection is usually other infected cattle, although in some countries, pulmonary or genitourinary TB in man, or bovine TB in wild animals are sources of infection. Tuberculous animals with nonencapsulated lung lesions expel infected droplets into the air by coughing, and contaminate pasture via the feces. Adult animals are infected by inhalation of airborne dust particles as well as by ingestion of contaminated feed or water. Calves may become infected by drinking contaminated milk. Acute lesions are usually found in the thorax and sometimes in the lymph nodes of the head or intestines. Lesions may be found in many organs in advanced stages of the disease and in tissues that seldom are primarily affected; thus, infection of the udder, uterus, various lymph nodes, kidneys, and the meninges occurs with varying frequency. The skeletal muscles are seldom affected, even in advanced cases. TB of the udder is of special significance because of the contamination of milk with viable tubercle bacilli.

B106 Cysticercosis (Cysticercus bovis)

Taenia saginata occurs in the small intestine of man (the only definitive host) and the metacestode (Cysticercus bovis) is found in cattle although other ruminants will serve as intermediate hosts (i.e. llama, reideer). T. saginata has a cosmopolitan distribution and the infection is particularly important in Africa and South America and in some Mediterranean countries.

B107 Dermatophilosis

(Dermatophilus infection, Cutaneous streptotrichosis, Lumpy wool, Strawberry foot rot)

An infection of the epidermis, seen worldwide, but more prevalent in the tropics, also called, erroneously, mycotic dermatitis. The lesions are characterized by exudative dermatitis with scab formation. Dermatophilus congolensis has a wide host range. In domestic animals, the condition most frequently affects cattle, sheep, and goats; it occasionally affects horses, but is rare in pigs, dogs, and cats. It is commonly called cutaneous streptotrichosis in cattle, goats, and horses; in sheep, it is termed lumpy wool when the wooled areas of the body are affected, and strawberry foot rot when the distal portions of the limbs are affected. The few human cases reported usually have been associated with handling diseased animals.

B108 Enzootic bovine leukosis

(Lymphosarcoma, Malignant lymphoma, Leukemia)

The term leukosis indicates a malignant proliferation of leukocyte-forming tissue. Because lymphoid tumors predominate in cattle, lymphosarcoma and malignant lymphoma are synonymous. Sometimes, the disease is called leukemia, but the presence of malignant cells in blood is not a consistent finding. Four clinicopathologic syndromes are recognized: calf, thymic, skin, and adult. The first 3 forms are called sporadic leukosis because there is no evidence that they are contagious. The adult syndrome, also known as enzootic leukosis, is caused by the bovine leukosis virus (BLV). Sporadic leukosis occurs worldwide, whereas the geographic distribution of enzootic leukosis is directly related to BLV prevalence. Sheep and goats can be infected experimentally with BLV, and most infected sheep develop lymphosarcoma. There have been a few reports of naturally infected flocks, but the source and mechanism of infection for these are unknown. All evidence indicates that BLV does not spread from sheep to cattle or from cattle to sheep by normal contact. Epidemiological and serological studies have failed to show any evidence of human infection or disease associated with exposure to BLV.

B109 Haemorrhagic septicaemia

An acute pasteurellosis, principally of cattle and water buffalo, that frequently reaches epidemic proportions. HS is a major disease of cattle and water buffalo in southern and eastern Asia, Africa, and some countries of southern Europe and the Middle East. Although it may occur at any time of year, the worst epidemics occur during the rainy season. It is most common in the river valleys and deltas of southeast Asia among buffaloes used in rice cultivation. Water buffalo are thought to be more susceptible than cattle. There have been reports of HS in horses, pigs, deer, bison, camels, elephants, and yaks. It is likely that wild cattle and buffalo are also susceptible. As few as 20,000 bacteria given subcut. can kill a susceptible buffalo. Laboratory rabbits and mice are highly susceptible to experimental infection. HS is caused by 1 of 2 serotypes of Pasteurella multocida.

B110 Infectious bovine rhinotracheitis (IBR/IPV)

(Infectious bovine rhinotracheitis (IBR), Infectious pustular vulvovaginitis (IPV), and associated syndromes)

Bovine herpesvirus 1 (BHV-1) can cause mild to severe syndromes in cattle of all ages and breeds. Furthermore, it can affect many body systems and thereby manifest itself in several forms, including respiratory disease, abortions, encephalitis, a systemic disease, conjunctivitis, or genital infection. In feedlot cattle, the respiratory form is most common; in breeding cattle, abortions or genital infections are more common. Following recovery from infection, the virus usually is maintained in a latent state that can be reactivated periodically following transport, concurrent disease, other stress, or corticosteroid treatment. Animals with latent infections generally show no clinical signs when the virus is reactivated, but they do serve as a source of infection for other susceptible animals and thus perpetuate the disease. Although there are strain differences within the BHV-1 group, there is little association with particular syndromes; all forms of the disease can be caused by the same isolate under appropriate conditions. The virus can be isolated from nasal, ocular, and vaginal secretions, and semen and preputial washings.

B111 Theileriosis

Infection by Theileria spp excluding B070 Trypanosomiasis (Nagana), B130 Benign bovine theileriosis and B131 Corridor disease.

B112 Trichomoniasis

(Bovine trichomoniasis)

A venereal, protozoal disease of cattle characterized by early fetal death and infertility associated with greatly extended calving intervals. Distribution is worldwide. The cause is a piriform protozoan, Tritrichomonas (Trichomonas) foetus.

B113 Trypanosomiasis

(Tsetse-transmitted trypanosomiasis)

A group of diseases caused by protozoa of the genus Trypanosoma, which affect all domestic animals. The major species are T congolense, T vivax, T brucei, and T simiae. In order of importance, those affecting cattle, sheep, and goats are T congolense, T vivax, and T brucei. In pigs, T simiae is the most important. In dogs and cats, T brucei is probably the most important. It is difficult to assign an order of importance for horses and camels.

B114 Bovine malignant catarrh

(Malignant catarrhal fever (MCF), Malignant head catarrh, Snotsiekte, Catarrhal fever, Gangrenous coryza)

An acute, sporadic, infectious disease of cattle and some other Bovidae and Cervidae, characterized by low morbidity and extremely high mortality, although on occasions, morbidity can be high, particularly in susceptible species such as Pere David's deer and Bali cattle. MCF has become an important disease of farmed deer. While MCF is a single clinicopathological entity, there are at least 2 distinct but related agents that can cause the disease naturally. One, alcelaphine herpesvirus 1 (AHV-1), which is carried inapparently by wildebeest (Connochaetes taurinus), is prevalent in Africa and in zoological parks, and is responsible for "wildebeest-derived" MCF (WD-MCF). The other principal cause is the "sheep-associated" (SA) agent of MCF. While the SA-MCF agent has not been isolated, molecular and serological evidence indicate it is similar to AHV-1. It occurs worldwide and is thought to infect most domestic sheep, usually without causing disease.

B115 Bovine spongiforme encephalopathy (BSE)

A progressive, fatal, nervous disease of adult domestic cattle, which closely resembles scrapie of sheep and goats; it was first diagnosed in Britain in 1986. The causal agent has not been identified, but similarities between BSE and scrapie suggest that it belongs to a group of incompletely characterized microorganisms called unconventional viruses or prions. These agents, in addition to scrapie, cause transmissible mink encephalopathy, chronic wasting disease of mule deer, and kuru and Creutzfeldt-Jakob disease of man.

B130 Benign bovine theileriosis

Theileria mutans was first described as a benign parasite of the ox by Theiler, but its identity was inextricably confused with that of other benign species of Theileria for many years. It was assumed to be the only benign bovine Theileria in Africa until 1977 when it was demonstrated that Theileria taurotragi was also capable of causing a mild clinical reaction in cattle. Elsewhere in the world the benign Theileria of cattle is considered to be Theileria orientalis. Theileria mutans is now known to be confined to eastern, western and southern Africa and to the Caribbean Islands where it was introduced in cattle from Africa. The parasite also infects the African buffalo, in which it was first described under the name Theileria barnetti. Its only practical significance in southern Africa is the confusion that it causes in the differential diagnosis of members of the Theileria parva complex. In East Africa, pathogenic strains of the parasite occur which may cause severe clinical illness and death.

B131 Corridor disease

Corridor disease is an acute, usually fatal disease of cattle resembling East Coast fever and is caused by infection with Theileria parva lawrencei which is transmitted by ticks from African buffaloes. The disease was first recognized in 1934 in Zimbabwe as a form of pathogenic theilerial infection distinguishable from East Coast fever on clinical, pathological, parasitological and epidemiological grounds. Previous occurrences in the region may well have been obscured by the widespread prevalance of East Coast fever. Twenty years later the disease was recognised in South Africa and the causal organism was identified as a new species, Theileria lawrencei, by Neitz in 1955. Subsequent investigation revealed that immunologically the parasite was a member of the Theileria parva complex and it was proposed as a subspecies of Theileria parva, namely, Theileria parva lawrencei. The disease and its causal organism are described by Neitz. The disease has been named buffalo disease, for obvious reasons, and corridor disease, because the first outbreak in South Africa occurred in the corridor between the Hluhluwe and Umfolozi Game Reserves in Natal. It occurs sporadically throughout southern and eastern Africa wherever there is contact between cattle and infected African buffaloes in the presence of ticks, Rhipicephalus appendiculatus, R. zambeziensis and R. duttoni.

 

 

B151 Brucella ovis infection

(Brucellosis in sheep)

B ovis produces a disease unique to sheep: epididymitis and orchitis impair fertility, which is the principal economic effect. Occasionally, placentitis and abortion are observed and there may be perinatal mortality. The disease was first described in New Zealand and Australia, and has since been reported from most sheep-raising areas of the world.

B152 Caprine and ovine brucellosis (Brucella melitensis)

Brucella melitensis infection in sheep causes clinical disease similar to that in goats. The signs of brucellosis in goats are similar to those in cattle. The disease is prevalent in most countries where goats are a significant part of the animal industry. It is rare in the USA. The causal agent usually is Brucella melitensis, but B abortus has been implicated. Infection occurs primarily through ingestion of the organism, but conjunctival, vaginal, and subcut. inoculations will produce disease. The disease causes abortion about the fourth month of pregnancy. Rarely, arthritis and orchitis occur, and keratitis and chronic bronchitis may be caused by infection with B melitensis.

B153 Caprine arthritis/encephalitis

A disease syndrome most often manifest in adult dairy goats as chronic, nonresponsive arthritis and mastitis, and in young goats as encephalitis (leukoencephalomyelitis). Serology suggests that the virus is widely distributed among dairy goats in most industrialized countries but rare among indigenous goats of developing countries. The disease has been described in North America, Europe, Australia, and New Zealand. Sheep have been infected experimentally. Currently, there is no evidence that CAE virus (CAEV) will infect man; however, pasteurization of goat milk for human consumption is recommended since it contains high levels of the virus and is a potential source of organisms of zoonotic concern, such as Coxiella burnetii and Salmonella spp. CAEV is a nononcogenic retrovirus in the subfamily Lentivirinae and is antigenically related to the virus of ovine progressive pneumonia and maedi-visna.

B154 Contagious agalactia

Although CA is usually caused by Mycoplasma agalactiae, at least 3 other mycoplasmas, viz M mycoides mycoides (large colony type, Mmm LC), M capricolum, and M putrefaciens, can cause a transmissible mastitis in small ruminants, particularly goats. Although, occasionally, several other mycoplasma species can be isolated from the udder of sheep and goats, they probably do not cause disease at this site. Mycoplasma agalactiae and M putrefaciens most frequently localize in the udder, and M capricolum in the joints, while Mmm LC is usually associated with a complex syndrome of signs. However, distinguishing between these organisms clinically can be difficult, and in those countries where 2 or more of them commonly occur (eg, Spain, Portugal, France), the term CA is applied to a syndrome of agalactia and polyarthritis, with or without other signs and regardless of the cause. Mycoplasma agalactiae causes subacute or chronic disease in both goats and sheep. It has been reported from many countries around the world, most often in the Mediterranean basin.

B155 Contagious caprine pleuropneumonia

A contagious pneumonia with pleurisy; it occurs commonly in goats in many parts of the Middle East, Africa, and Asia, less commonly in the Mediterranean countries and Central and North America. Acute pneumonias in goats are caused by Mycoplasma strain F38, M mycoides mycoides (large colony type, Mmm LC), and M mycoides capri. Strain F38 causes a highly contagious lethal disease most resembling the earlier descriptions of classical contagious caprine pleuropneumonia, and appears to be transmitted by infective aerosol. Morbidity can be 100% and mortality 60-100%. Gathering or housing animals together facilitates spread of the disease.

B156 Enzootic abortion of ewes

A worldwide, infectious disease manifest by abortion and, to a lesser extent, by stillbirth or premature parturition. Eye infections in laboratory workers, and abortions in women who had contact with aborting sheep have been reported. The causative agent comprises immunotype 1 strains of Chlamydia psittaci, identical to the one associated with bovine chlamydial abortion. Strains recovered from aborted fetuses of sheep or cattle cause abortion in either species.

B157 Pulmonary adenomatosis (Jaagsiekte)

A contagious, viral, neoplastic disease of the lungs of sheep and more rarely of goats. It has been reported from Europe, Asia, Africa, and South and North America. Respiratory exudates from affected sheep are infectious. The causal agent has not been established, although a retrovirus has been identified in the tumor and fluids. A herpesvirus also has been recovered from the tumor, but does not appear to have an etiological role. Natural transmission seems to occur generally by the respiratory route. Close contact, eg, at feeding troughs, may assist spread of the virus.

B158 Nairobi sheep disease

A tick-borne viral disease of sheep and goats characterized by fever and gastroenteritis. It occurs in Kenya, Uganda, Tanzania, Somalia, Ethiopia, and Zaire. Although man is susceptible, human infections are rare. The causal nairovirus, family Bunyaviridae, is possibly the most pathogenic virus known for sheep and goats. It is closely related to Ganjam virus, a tick-borne infection in India of sheep, goats, and man; to Dugbe virus, another tick-borne infection; and Crimean-Congo hemorrhagic fever virus. It is transmitted transovarially and transtadially by the brown ear tick, Rhipicephalus appendiculatus, in which it can survive for ~22 yr. Other Rhipicephalus and Amblyomma ticks also may transmit the disease. The virus is shed in the urine and feces, but the disease is not spread by contact.

B159 Salmonellosis (Salmonella abortus ovis)

Salmonella infections in sheep and goats are manifested by the development of two distinct syndromes: an acute to subacute septicaemic disease with an associated diarrhoea, and abortion. The septicaemic syndrome is precipitated by stress and is characterized by the development of a watery-green to blood-tinged diarrhoea, the consequence of a severe necrohaemorrhagic ileitis, typhlitis and colitis. Although the septicaemic disease in sheep is less prevalent than bovine salmonellosis, its occurrence and economic importance appear to be increasing in South Africa with the development of the sheep feedlot industry. In the United Kingdom and Australia, Salmonella abortus ovis, Salmonella dublin, and Salmonella typhimurium infections have been incriminated as causes of abortion in sheep. Abortions due to infections by Salmonella serovars have not been documented in South Africa.

B160 Scrapie

A degenerative neurologic disease of sheep, it is the prototype of the "slow virus" infections that produce subacute spongiform encephalopathies in animals and man. Each of transmissible mink encephalopathy (TME), chronic wasting disease of captive mule deer and elk, kuru, Creutzfeldt-Jakob disease, and bovine spongiform encephalopathy is defined by the clinicopathologic features in their natural hosts; all are transmissible to other species in which they are virtually indistinguishable. The causal neuropathogens have properties so unusual that they are called "unconventional viruses". Although viral or subviral in size, the lack of identification of any agent-specific nucleic acids or proteins has severely limited progress in their characterization and lead to speculation that they represent new forms of "infectious" entities capable of producing cell death and tissue degeneration. Scrapie is naturally transmitted to susceptible sheep by contact with infected animals or pastures. There is no clear evidence that it is vertically transmitted in the genome or by embryo transfer, despite its common familial occurrence.

B161 Maedi-Visna

(Progressive pneumonia, Zwoegersiekte)

A chronic, progressive, viral disease of sheep and goats. In sheep, the virus affects principally the lungs and udder, but the central nervous system and joints also may be affected. The disease has been reported from North and South America, Europe, Africa, and Asia. The disease in sheep has never been encountered in Australia and New Zealand, although the disease in goats is prevalent in these countries. The causal RNA virus (a lentivirus), which persists in the white blood cells of infected sheep in the presence of a humoral and cell-mediated immune response, is detectable by several serological tests.

B170 Sheep scab

Psoroptic scabies (sheep scab) is a notifiable disease, and affected flocks are subject to quarantine and dipping regulations. Countries where sheep scabies (scab) is still a problem include the UK, Eire, France, Germany, Lebanon, Israel, Egypt, South Africa, Kenya, Argentina, Brazil, and Mexico. It occurs almost exclusively on the woolly parts of the body where it produces large, scaly, crusted lesions. Biting and scratching brought on by intense itching are generally the first signs. When large areas are involved, animals gradually become emaciated and suffer from anemia and cachectic hydremia. Psoroptic mites are sometimes found in the ears of sheep.

B201 Contagious equine metritis

A highly contagious venereal disease of horses and, experimentally, donkeys. In most areas, the disease must be reported to regulatory authorities. The causal agent is a gram-negative coccobacillus, once arguably classified in the genus Haemophilus, now designated Taylorella equigenitalis.

B202 Dourine

An often chronic venereal disease of horses, transmitted during coitus, and caused by Trypanosoma equiperdum. The disease is recognized on the Mediterranean coast of Africa, the Middle East, southern Africa, and South America; distribution is probably wider.

B203 Epizootic lymphangitis

A chronic granulomatous disease of the skin, lymph vessels, and lymph nodes of the limbs and neck of Equidae, caused by the dimorphic fungus Histoplasma farciminosum. The disease occurs in the Orient and Mediterranean areas but is unknown in the USA. The fungus forms mycelia in nature and yeast forms in tissues, and has a saprophytic phase in soil. Infection probably is acquired by wound infection or transmission by blood-sucking insects.

 

 

B204 Equine encephalomyelitis

(Equine encephalitis)

The equine encephalitides are clinically similar syndromes characterized by signs of central nervous system dysfunction and moderate to high mortality. Various arboviruses classically have been regarded as the causal agents, but toxoplasma-like protozoal agents also have been incriminated. The causal arboviruses are transmitted by mosquitoes or ticks and infect a variety of other vertebrate hosts, including man, in which they occasionally cause serious infections. In general, these arboviruses utilize a rodent-or bird-mosquito cycle. Horses may be infected by alphaviruses, family Togaviridae, or flaviviruses, family Flaviviridae. The alphaviruses most closely associated with equine encephalitis include Eastern (EEE), Western (WEE), and Venezuelan (VEE) equine encephalomyelitis viruses. Other alphaviruses associated virologically or serologically with clinical encephalitis in Equidae are Aura, Ross River, Semliki Forest, and Una viruses, but these agents appear to be only infrequently or incidentally associated with disease.

B205 Equine infectious anaemia

(EIA, Swamp fever)

An acute or chronic viral disease of Equidae, found wherever there are horses. The virus is related to the human AIDS lentivirus, but it is not known to infect man.

B206 Equine influenza (Virus type A)

An acute, highly contagious, febrile respiratory disease. Two immunologically distinct influenza viruses have been found in horse populations worldwide except in Australia and New Zealand. Orthomyxovirus A/Equi-1, although probably present for decades, has not been isolated anywhere since 1980; orthomyxovirus A/Equi-2 was first recognized in 1963 as a cause of widespread epidemics, following which the virus has become endemic in many countries.

B207 Equine babesiosis (Equine piroplasmosis)

Equine babesiosis, more commonly known as biliary fever, is an acute, subacute or chronic tick-borne disease of Equidae caused by the intra-erythrocytic protozoa Babesia equi and Babesia caballi. It is characterized by fever (which is sometimes intermittent), progressive anaemia, icterus, hepatomegaly and splenomegaly. Bilirubinuria and haemoglobinuria may be present in the later stages of the disease. Pregnant animals may abort as a result of these infections.

B208 Equine rhinopneumonitis

(Equine herpesvirus 1 infection, Equine viral rhinopneumonitis, Equine abortion virus)

Equine herpesvirus 1 (EHV-1) comprises 2 genetically and antigenically distinct groups of viruses now commonly referred to as subtypes 1 and 2 of EHV-1, but until recently considered separate herpesviruses designated EHV-1 and EHV-4. EHV-1 is ubiquitous in horse populations throughout the world. Both subtypes produce acute febrile respiratory disease on primary infection, characterized by rhinopharyngitis and tracheobronchitis. Outbreaks of respiratory disease occur annually among foals in areas with concentrated horse populations; elsewhere episodes are sporadic. Most of these outbreaks in weanlings are caused by subtype 2 strains. The age, seasonal, and geographic distributions vary, and probably are determined by immune status and concentration of horses. In individuals, the outcome of exposure is determined by viral strain involved, immune status, pregnancy status, and possibly age. Infection of pregnant mares with subtype 2 strains rarely results in abortion.

B209 Glanders

(Farcy)

A contagious, acute or chronic, usually fatal disease of Equidae, caused by Pseudomonas mallei and characterized by serial development of ulcerating nodules that occur most commonly in the upper respiratory tract, lungs, and skin. Man, Felidae, and other species are susceptible, and infections usually are fatal. Glanders is one of the oldest diseases known and once was prevalent throughout the world. It has now been eradicated or effectively controlled in many countries. Pseudomonas mallei is present in exudates of the nose and ulcerative skin of infected animals, and the disease is commonly contracted by ingesting food or water contaminated by the nasal discharge of carrier animals. The organism is susceptible to heat, light, and disinfectants, and is unlikely to survive in a contaminated area for >6 wk.

B210 Horsepox

Horsepox is a benign disease characterized by the development of typical pox lesions either on the limbs or on the lips and buccal mucosa. The causative ungulate poxvirus is identical antigenically with the virus of true cowpox and is transferrable to cattle and to man. Horsepox occurs only in Europe and appears to be quite rare. In general it is a benign disease, but badly affected horses become debilitated and occasionally young animals may die.

B211 Infectious arteritis of horses (Equine viral arteritis)

This disease of horses is caused by a specific virus and is manifested clinically by an acute, upper respiratory tract infection and abortion in mares. It is chracterized by specific lesions in the small arteries. A togavirus is the cause of the disease. It has no relationship to human or porcine influenza viruses and only one antigenic type of the virus is known to occur.

B212 Japanese encephalitis

In terms of public health, Japanese encephalitis virus is the most important flavivirus that causes equine encephalitis; it is recognized throughout the Far East.

B213 Horse mange

Sarcoptic mange (Sarcoptes scabiei var equi) is the most severe type. Early lesions appear on the head, neck, and shoulders. Regions protected by long hair, and lower parts of the extremities usually are not involved. The first sign is intense itching. Small papules and vesicles develop into an acute dermatitis; scaling increases rapidly, followed by crusting. The bald and encrusted patches enlarge and the skin thickens, forming folds, particularly in the neck region. In advanced cases, the lesions may extend over the entire body, leading to emaciation, general weakness, and anorexia. The course is chronic, and the prognosis is the most unfavorable of all types of mange in horses, particularly when the infestations are severe and the animals are in poor condition. For treatment, acaricidal preparations are applied by spraying, rubbing, or dipping. For groups of animals, dipping is the most convenient and effective method. Psoroptic scabies (Psoroptes ovis [equi]) is a notifiable and quarantinable disease in the countries in which it is found. It produces lesions on sheltered parts of the body, such as under the forelock and mane, at the root of the tail, under the chin, between the hindlegs, and in the axillae. Mites are sometimes found in the ears and may cause head shaking. The lesions are similar to the sarcoptic type, but the crusts are larger and thicker, the skin is less folded, and the itching is less severe. The course is chronic and the prognosis favorable. Treatment corresponds to that for the sarcoptic type, or to the dips used for psoroptic scabies of cattle. Chorioptic mange (Chorioptes bovis) is also known as "leg mange". Cutaneous lesions are found chiefly on the lower parts of the hindlegs. In severe cases, skin lesions may spread to the flanks, shoulders, and neck. The disease is characterized by intense itching, scales, crusts, thickening of the skin, and in neglected cases, a moist dermatitis in the fetlock region. The signs subside in summer, but recur with the return of cold weather. The course usually is chronic, the prognosis favorable. Treatments recommended for other mange mites are effective against chorioptic mange. Demodectic mange (Demodex equi) is seldom diagnosed in horses. The mites live in the hair follicles and in the sebaceous glands and produce papules and ulcers, particularly around the eyes and on the forehead. Subsequently, the lesions spread to the shoulders and finally over the entire body. The affected skin is covered with scales. Pruritus is absent. There is no satisfactory treatment.

B215 Surra (Trypanosoma evansi)

This is separated from the tsetse-transmitted diseases because it is usually transmitted by other biting flies that occur within and outside tsetse fly areas. It is essentially a disease of camels and horses. It occurs in North Africa, the Middle East, Asia, the Far East, and Central and South America. The distribution of T evansi in Africa extends into the tsetse areas, where it is difficult to differentiate from T brucei. All domestic animals are susceptible, and the disease can be fatal, particularly in camels, horses, and dogs. Trypanosoma evansi in other animals appears to be nonpathogenic, and these animals serve as reservoirs of infection. Transmission is primarily by biting flies, probably resulting from interrupted feedings. A few wild animals are susceptible to infection and may serve as reservoirs.

B216 Venezuelan equine encephalomyelitis

(Equine encephalitis)

The equine encephalitides are clinically similar syndromes characterized by signs of CNS dysfunction and moderate to high mortality. Various arboviruses classically have been regarded as the causal agents, but toxoplasma-like protozoal agents also have been incriminated (see also p365 and p594). The causal arboviruses are transmitted by mosquitoes or ticks and infect a variety of other vertebrate hosts, including man, in which they occasionally cause serious infections. In general, these arboviruses utilize a rodent- or bird-mosquito cycle. Etiology and Epidemiology: Horses may be infected by alphaviruses, family Togaviridae, or flaviviruses, family Flaviviridae. The alphaviruses most closely associated with equine encephalitis include Eastern (EEE), Western (WEE), and Venezuelan (VEE) equine encephalomyelitis viruses.

B251 Atrophic rhinitis

A disease of pigs characterized by sneezing, followed by atrophy of the turbinate bones, which may be accompanied by distortion of the nasal septum, and shortening or twisting of the upper jaw. The etiology is complex and involves at least 2 organisms. Various infections, eg, inclusion body rhinitis and pseudorabies, and noninfectious agents may cause sneezing and tear-staining, usually without leading to atrophic rhinitis. Bordetella bronchiseptica has long been implicated as a major cause. This bacterium is not host-specific, although strains that cause atrophic rhinitis are generally isolated only from pigs. Dogs, cats, rodents, and other species may harbor B bronchiseptica for long periods, but their role in the spread of atrophic rhinitis in pigs is uncertain. Certain toxigenic strains of Pasteurella multocida, often acting with B bronchiseptica, cause permanent turbinate atrophy and nasal distortion. Because both organisms can cause clinical atrophic rhinitis, the disease has now been divided into 2 forms: regressive atrophic rhinitis, due to B bronchiseptica, is mild and transient and probably does not affect the animal's growth and performance; progressive atrophic rhinitis,

caused by toxigenic P multocida, is severe and permanent and usually results in poor growth.

 

B252 Cysticercosis (Cysticercus cellulosae)

Cysticercosis: Taenia solium is an intestinal parasite of man. Cysticerci (once regarded as a separate parasite, Cysticercus cellulosae) occur in the flesh of pigs, but may also develop in man and dogs that have ingested the eggs. They commonly localize on the meninges and in the neuropil, and may cause convulsions and locomotor disturbances.

B253 Porcine brucellosis (Brucella suis)

Clinical manifestations of brucellosis in pigs vary considerably, but are similar in many respects to those seen in cattle and goats. Although the disease is often self-limiting, it has remained in some herds for years. Brucellosis caused by B suis also occurs in other domestic animals and man. Epidemics of human brucellosis have been reported among packing-house workers, and the usual source is infected pigs. Brucella suis is spread mainly by close animal contact, usually by ingestion of infected tissues or wastes. Infected boars may transmit the disease during service; the organism can be recovered from semen.

B254 Transmissible gastroenteritis of pigs

A common viral disease of the small intestine that causes vomiting and profuse diarrhea in pigs of all ages. The causal coronavirus infects and destroys villous epithelial cells of the jejunum and ileum, which results in severe villous atrophy, malabsorption, osmotic diarrhea, and dehydration.

B255 Trichinellosis

Trichinella spiralis occurs in the small intestine of man, pig, rat and many other mammals. Even birds have been infected experimentally. It is probably cosmopolitan in distribution; although it has not been reported from some countries it is recognized in most of the northern hemisphere, Africa, Asia and South America. Strain differences have been demonstrated in T. spiralis, including different infectivities for experimental animals and pigs and these differences have been confirmed by interbreeding experiments. As a result it has been proposed that T. spiralis should be divided into four species. T. spiralis remains the synanthropic-zoonotic species which occurs primarily in rats, pigs and mice. T. nativa occurs as a sylvatic cycle in wild carnivores in areas such as Canada and the USSR, mostly north of latitude 38 /N. T. nelsoni is found in wild carnivores primarily in eastern and southern Africa, but has also been recognized in the southern parts of the USSR, Eastern Europe (Bulgaria) and Switzerland. T. pseudospiralis has been isolated from a raccoon in the northern caucasis; it may occur in India.

According to the textbook, Veterinary Helminthology by R. K. Reinecke, T. spiralis has not yet been recorded in man in the RSA, but a sylvatic cycle exists in wild animals in the Kruger National Park.

B256 Enterovirus encephalomyelitis

(Porcine enteroviral encephalomyelitis, Teschen disease, Porcine polioencephalomyelitis, Talfan disease, Benign enzootic paresis)

An infectious disease of pigs, analogous to human poliomyelitis. Severe disease is now rare; it occurs in the USSR and Africa but was last reported in Europe from Austria in 1980. In other countries, sporadic mild disease is reported, or the disease is unrecognized. Enteroviruses (Picornaviridae) are ubiquitous in swine populations throughout the world. Many strains are nonpathogenic.

 

 

B257 Porcine reproductive and respiratory syndrome (PRRS)

This "mystery" disease is characterized by reproductive dosorders (late-term abortions, premature farrowings, stillborns, mummification, and weak liveborn pigs), high piglet mortality, and respiratory disease in neonates to market pigs. The predominant reproductive and respiratory clinical signs associated with this syndrome have resulted in the descriptive term "Swine Infertility and Respiratory Syndrome" (SIRS), which has become the most commonly used name for mystery swine disease in the United States. The Netherlands and German isolates of PRRS and the U. S. isolate of SIRS have not been completely characterized and classified into an apprpriate virus family. The PRRS/SIRS viruses are antigenically similar. The mode of transmission of the disease is also unknown, but rapid spread of PRRS/SIRS between farms in some localities has been reported, suggesting airborne spread. Also, aerosol spread may be the most likely route of transmission because the disease can be readily reproduced in pigs and sows by intranasal inoculation. Sows apparantly shed the virus.

(Information derived from the textbook Diseases of swine, 7th Edition, Edited by: A. D. Leman, B. E. Straw, W. L. Mengeling, S. D'Allaire, D. J. Taylor, published by Wolfe Publishing Ltd).

B270 Actinobacillus (Haemophilus) pleuropneumoniae

A disease that most often affects soft tissues and lymph nodes, although bony structures also may be involved by direct extension; it is similar to actinomycosis (see below).. In pigs, septicemia, suppurative joint lesions, endocarditis, osteomyelitis, pneumonia, and infections of the mammary glands and soft tissue of the head have been recorded.

B301 Avian infectious bronchitis

An acute, rapidly spreading, viral disease of chickens, characterized by infection of respiratory, urogenital, and GI tract tissues. The causal coronaviruses are found worldwide and exist as numerous serotypes. Two or more serotypes may occur simultaneously in one geographic region. A disease of chickens only, the virus is present in respiratory discharges and feces, and on contaminated eggshells. It is spread by droplets through the air; by ingestion of contaminated feed and water; and by contact with infected chickens, contaminated equipment, and clothing of caretakers. Chickens infected with some strains excrete virus in the feces for b1 mo after clinical recovery. Virus infections in layers and breeders occur cyclically as immunity declines, or on exposure to different serotypes.

B302 Avian infectious laryngotracheitis

An acute, highly contagious, herpesvirus infection of chickens and pheasants characterized by severe dyspnea, coughing, and rales; or a subacute disease with lacrimation, tracheitis, conjunctivitis, and mild rales. It has been reported from most of the intensive-poultry-rearing sections of the USA and many other countries.

B303 Avian tuberculosis

An infectious disease caused by acid-fast bacilli of the genus Mycobacterium. Although commonly defined as a chronic, debilitating disease, TB occasionally assumes an acute, rapidly progressive course. The disease affects practically all species of vertebrates, and before control measures were adopted, was a major disease of man and domestic animals. Signs and lesions are generally similar in the various species. Etiology: Three main types of tubercle bacilli are recognized: human, bovine, and avian; respectively, M tuberculosis, M bovis, and M avium complex (M avium-intracellulare-scrofulaceum). The 3 types differ in cultural characteristics and pathogenicity. The 2 mammalian types are more closely related to each other than to the avian type. More than 30 serovars of M avium complex are recognized; however, only serovars 1 and 2 are pathogenic for birds.

B304 Duck virus hepatitis

An acute, highly contagious, viral disease of young ducklings, characterized by a short incubation period, sudden onset, high mortality, and characteristic liver lesions. Three distinct types of duck hepatitis virus (DHV) have been isolated from diseased ducks. The disease is of economic importance in all duck-raising areas of the world. A natural outbreak of DHV Type I has been reported in mallard ducklings. Experimental Type I infections have been produced in goslings, turkey poults, young pheasants, quail, and guinea fowl. The originally described and most virulent DHV, Type I, is a picornavirus and is readily propagated in chick and duck embryos.

B305 Duck virus enteritis (duck plague)

An acute, highly contagious infection of ducks, geese, and swans of all ages, characterized by sudden death, high mortality, and hemorrhages and necrosis in internal organs. It has been reported in domestic and wild waterfowl of Europe, Asia, North America, and Africa, and has resulted in serious or limited economic losses in the duck industries and massive and limited die-offs of wild waterfowl. The causal herpesvirus is nonhemagglutinating and nonhemadsorbing, and produces intranuclear inclusion bodies in infected tissues and tissue cultures. All strains are antigenically similar, but vary in virulence. Egg transmission probably does not occur in domestic ducks, but has been demonstrated in infected carrier wild waterfowl. Infection can be transmitted by parenteral, intranasal, or oral administration of infected tissues. Recovered birds may remain carriers.

B306 Fowl cholera

A contagious, widely distributed disease affecting domestic and wild birds. It usually occurs as a septicemia of sudden onset with high morbidity and mortality, but chronic and asymptomatic infections also occur. Pasteurella multocida, the causal agent, is a small, gram-negative, nonmotile ro

B307 Fowlpox

A worldwide, slow-spreading viral infection of chickens and turkeys characterized by proliferative lesions in the skin (cutaneous form) that progress to thick scabs, and by lesions in the upper GI and respiratory tracts (diphtheritic form). The large DNA virus (an avipoxvirus, family Poxviridae) is highly resistant and may survive for several years in dried scabs. Field and vaccine strains have only minor differences in their genomic profiles, although the strains can be differentiated by electrophoresis. The virus is present in large numbers in the lesions and is usually transmitted by contact to pen mates through abrasions of the skin. Mosquitoes and other biting insects may serve as mechanical vectors. Transmission within flocks is rapid when mosquitoes are plentiful. Some affected birds may become carriers, and the disease may be reactivated by stress, such as moulting or by immunosuppression due to other infections.

B308 Fowl typhoid (Salmonella gallinarium)

The causal agent, S gallinarum, is very similar to S pullorum, and many consider them as one. Infection is rare in many countries, including the USA and Canada, but is a major problem in others. Although S gallinarum is egg-transmitted and produces lesions in chicks and poults similar to those produced by S pullorum, it has a much greater tendency to spread among growing or mature flocks. Mortality at all ages usually is high.

B309 Gumboro disease (Infectious bursal disease)

An acute, highly contagious, birnavirus infection of young chickens that occurs worldwide. Infections before 3 wk of age are normally subclinical but cause immunosuppression due to widespread destruction of undifferentiated lymphocytes. In recent years, "variant" strains of IBD virus have been identified that cause immunosuppression but do not induce clinical disease in older chickens. These strains have major antigenic differences from the "standard" strains.

B310 Marek's disease

Chickens are the only important natural host, but quail and turkeys can be infected experimentally. Turkeys are commonly infected with turkey herpesvirus, an avirulent strain related to Marek's disease virus. Other birds and mammals appear to be refractory to the disease or infection. Marek's disease is one of the most ubiquitous avian infections; it is identified among chicken flocks worldwide. Every flock except for those maintained under strict pathogen-free conditions may be presumed to be infected. Although clinical disease is not always apparent in infected flocks, a subclinical decrease in growth rate and egg production may be economically important. Three serotypes of the cell-associated herpesvirus are recognized: serotypes 1 and 2 designate virulent and avirulent chicken isolates, respectively; serotype 3 designates the related avirulent turkey herpesvirus. Serotypes 2 and 3, as well as attenuated serotype 1 viruses have been used as vaccines. Serotype identification is accomplished by reaction with type-specific monoclonal antibodies or by biological characteristics such as host range, pathogenicity, growth rate, and plaque morphology.

B311 Mycoplasmosis (Mycoplasma gallisepticum)

(PPLO infection, Chronic respiratory disease [CRD], Infectious sinusitis)

MG infection is commonly designated as CRD in chickens, and infectious sinusitis in turkeys. Infection may also occur in pheasants, chukar partridges, and peafowl. Infection in pigeons, quail, ducks, geese, and psittacine birds should be considered. Passerine-type birds are quite resistant. The disease is worldwide. Its effects are most severe in large commercial operations during winter.

B312 Psittacosis and Ornithosis

(Chlamydiosis, Psittacosis, Ornithosis)

A reportable, widespread, zoonotic disease, caused by Chlamydia psittaci. It is not limited to newly imported psittacines, but also is seen in breeding collections (especially cockatiels and budgerigars) and in birds sold from retail outlets. Birds can carry the organism for years before developing disease under stress. When possible, birds should be obtained from breeding establishments known to be free of infection.

B313 Pullorum disease (Salmonella pullorum)

Infections by S pullorum usually cause high mortality in young chickens and turkeys and occasionally in adult chickens. A once common disease, it has been eradicated from most commercial stock. It usually occurs in other avian species only if they are in close contact with infected chickens or turkeys. Infection in mammals is rare.

B330 Ostrich influenza

A viral disease of domestic and wild birds with signs ranging from almost no clinical disease to high mortality. The incubation period also is highly variable, and ranges from a few days to 1 wk. The causal orthomyxoviruses are type A influenza viruses. Both virulent and avirulent viruses with any of 13 known surface hemagglutinins are known to infect avian species. The viruses grow readily in embryonating chicken eggs and agglutinate RBC. Specific inhibition of this hemagglutination is the basis for the serological test for influenza antibodies. The viruses have a worldwide distribution and frequently are recovered from clinically normal sea birds, migrating waterfowl, imported pet birds, and live bird markets.

B351 Myxomatosis

B352 Tularaemia

B353 Viral haemorrhagic disease of rabbits

B401 Viral haemorrhagic septicaemia (VHS)

Viral haemorrhagic septicaemia is a coldwater rhabdovirus infection of rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), grayling (Thymallus thymallus), white fish (Coregous sp.), pike (Esox lucius) and turbot (Scophthalmus maximus). Infections with VHS virus in Pacific salmon, Pacific cod and Pacific herring have always been associated with genetically characteristic virus strains, which appear to be of low pathogenicity to rainbow trout. It occurs in continental Europe, but is mainly a matter of concern, because of its clinical and economic consequences in rainbow trout farming. The infection of fish is often lethal, due to the impairment of the salt-water balance, which occurs in a clinical context of oedema and haemorrhages. Virus multiplication in endothelial cells of blood capilliaries, leucocytes, haematopoietic tissues and nephron cells, underlies the clinical signs. In survivors, VHS virus infection results in strong protective immunity, synthesis of circulating antibodies to VHS virus as well as, in certain individuals, an asymptomatic carrier state. This carrier state frequently turns to high virus excretion at times of spawning.

B404 Spring viraemia of carp (SVC)

Spring viraemia of carp (SVC) is a rhabdovirus infection of several carp species and of some other cyprinid fish species. Overt infections have been recognised in common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idellus), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), crucian carp (Carassius carassius), goldfish (Carassius auratus), tench (Tinca tinca) and sheatfish (Silurus glanis). The geographic range of SVC is currently limited to countries of the European continent which experience low water temperatures during winter. Infection by SVC virus can be lethal, due to, as in other rhabdoviroses of fish, the impairment of salt-water balance, which occurs in a clinical context of oedema and haemorrhages. Virus multiplication, especially in endothelial cells of blood capilliaries, haematopoietic tissue and nephron cells, underlies the clinical signs. Overcoming SVC virus infection results in a strong protective immunity associated with the presence of circulating antibodies.

B405 Infectious haematopoietic necrosis (IHN)

Infectious hemopoietic necrosis is a rhabdovirus infection of rainbow trout (Oncorhynchus mykiss) including steelhead, several Pacific salmon, i. e. sockeye (O. nerka), chinook (O. tshawystcha), chum (O. keta), yamame (O. masou), amago (O. rhodurus), and more recently coho (O. kisutch) and Atlantic salmon (Salmo salar). Until 1987, the geographic range of IHN was limited to the North Pacific Rim (North America and the Far East), but it has recently spread to continental Europe. IHN has become a real matter of concern because of its clinical and economic consequences in trout and salmon farming and in fisheries. Infection is often lethal, due to the impairment of the salt-water balance, which occurs in a clinical context of oedema and haemorrhages. Virus multiplication in endothelial cells of blood capillaries, haematopoietic tissues and nephron cells, underlies the clinical signs.

B408 Bacterial kidney disease (Renibacteriosis)

Bacterial kidney disease is a chronic infection with a protracted course and an insidious nature. Fish of the Salmonidae family are clinically susceptible, in particular those of the Oncorhynchus (Pacific salmon) genus. The diagnosis depends on increased low mortality, classical clinical and pathological changes associated with the disease as well as histopathological granulomatous changes, and isolation of Renibacterium salmoninarum in cysteine enriched media (KDM2 - SKDM) from the lesions or from asymptomatic (latent) carriers of the pathogen.

B413 Epizootic haematopoietic necrosis (EHN)

Epizootic haematopoietic necrosis (EHN) is an iridovirus infection of redfin perch (Perca fluviatilis) and rainbow trout (Oncorhynchus mykiss). The geographic range of the infection is currently restricted to Australia. The infection is most often lethal in perch and much less so in rainbow trout, in a clinical context of haemorrhages and oedema accompanied by necrotic lesions of the vascular walls, liver, spleen and haematopoietic tissue of the kidney. Necrotising hepatitis seems to be a consistent sign of the condition.

B415 Oncorhynchus masou virus disease (OMV)

Oncorhynchus masou virus disease is an oncogenic condition among salmonid fish in Japan and probably of the coastal rivers of Eastern Asia which harbour Pacific salmon. The causative virus (OMV) is also known as Yamane tumor virus (YTV), or Nerka virus Towada Lake, Akita and Amori prefecture (NeVTA). The susceptible fish species are kokanee salmon (Oncorhynchus nerka), masou salmon (O. masou), chum salmon (O. keta), coho salmon (O. kisutch) and rainbow trout (O. mykiss). Clinically, the initial infection by OMV appears as a systemic and frequently lethal infection which occurs in a context of oedema and haemorrhages. Virus multiplication in endothelial cells of blood capilliaries, haematopoietic tissue and hepatocytes underlies the clinical signs. Four months after this first clinical condition, a varying number of surviving fish exhibit epithelioma occurring mainly around the mouth (upper and lower jaw), and to a lesser extent, on the caudal fin operculum and body surface. These neoplasia may persist for up to one year post-infection. Following the septicaemia phase of OMV infection, an immune response takes place and results in the synthesis of neutralising antibodies to OMV. A carrier state frequently occurs which leads to virus shedding via the sexual products at times of spawning.

B420 Infectious pancreatic necrosis

Infectious pancreatic necrosis (IPN) is a highly contagious viral disease of young fish of salmonid species held under intensive rearing conditions. The disease most characteristically occurs in rainbow trout (Oncorhynchus mykiss), brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), Atlantic salmon (Salmo salar), and several Pacific salmon species (Oncorhynchus spp). IPN virus, or viruses showing serological relatedness to IPN virus, have been reported to cause diseases in some farmed marine fish species, such as cod (Gadus morhua), yellowtail (Seriola quinqueradiata), turbot (Scophthalmus maximus), and halibut (Hippoglossus hipoglossus), and subclinical asymptomatic infections have been detected in a wide range of estuarine and freshwater fish species in the families Anguillidae, Atherinidae, Bothidae, Carangidae, Cotostomidae, Cichlidae, Clupeidae, Cobitidae, Coregonidae, Cyprinidae, Esocidae, Moronidae, Paralichthydae, Pericdae, Poeilidae, Sciaenidae, Soleidae and Thymallidae. The causative agent, infectious pancreatic necrosis virus, is a bi-segmented double-stranded RNA virus belonging to the family Birnaviridae.

B431 Bonamiosis

B432 Haplosporidiosis

B433 Perkinsosis

B434 Marteiliosis

B435 Iridovirosis

B436 Mikrocytosis (Mikrocytos mackini)

B451 Acariasis of bees

B452 American foul brood

B453 European foul brood

B454 Nosematosis of bees

B455 Varroasis

B501 Leishmaniasis

The disease is caused by Leishmania spp. A variety of Phlebotomus spp have been shown to serve as vectors. It is a zoonoses and carnivores and rodents can act as reservoirs. It causes visceral leishmaniasis, Old World cutaneous leishmaniasis and American cutaneous leishmaniasis.

C611 Listeriosis

A sporadic bacterial infection with worldwide distribution that occurs more in temperate and colder climates. It affects a wide range of animals and birds, including man. There is a high incidence of intestinal carriers, and the disease occurs more commonly than it is diagnosed. Encephalitis or meningoencephalitis in adult ruminants is the most frequently recognized form. Etiology: Listeria monocytogenes.

C612 Toxoplasmosis

Toxoplasma gondii is a protozoan that infects most species of warm-blooded animals, including birds and man, in most parts of the world.

C613 Melioidosis

A bacterial infection characterized by suppurative or caseous lesions in lymph nodes and viscera. Macroscopically, the lesions have no characteristic feature; microscopically, there is a mixed purulent and granulomatous response. It is caused by Pseudomonas pseudomallei (Bacillus whitmori, Loefflerella pseudomallei, Malleomyces pseudomallei).

 

 

C614 Blackleg

An acute, febrile disease of cattle and sheep caused by Clostridium chauvoei (feseri) and characterized by emphysematous swelling, usually in the heavy muscles. The disease is found worldwide.

C615 Botulism

(Lamsiekte)

A rapidly fatal motor paralysis caused by the ingestion of the toxin of Clostridium botulinum; the organism proliferates in decomposing animal tissue and sometimes in plant material.

C616 Other Clostridial infections

Excluding C614 Blackleg and C615 Botulism.

C617 Other pasteurellosis

C618 Actinomycosis

A local or systemic, chronic, suppurative, granulomatous disease that affects a wide variety of domestic animals and, rarely, wild animals. Causative agents include Actinomyces bovis, A viscosus (first isolated from gingival plaques of hamsters with periodontal disease, but now known to be an important pathogen of dogs and, to a lesser extent, pigs and goats), A hordeovulneris, and A suis. The exact taxonomic classification of this latter species is undecided. Actinomyces bovis has been confirmed only from bovine infections. Predominantly human types, such as A israelii, may occasionally be recovered from lesions in other animals. Several species (A denticolens, A howellii, and A slackii) have been recovered from bovine dental plaque, but their pathogenic potential is undetermined.

C619 Intestinal Salmonella Infections

Enteropathogenic salmonellae cause inflammation and necrosis of the small and large intestine, resulting in diarrhea that may be accompanied by generalized sepsis. All ages are susceptible, but the disease is most common in weaned and growing-finishing pigs. Etiology and Pathogenesis: Salmonella choleraesuis var kunzendorf is the most common salmonella species affecting pigs. It sometimes produces necrotizing enterocolitis, but far more common is a septicemic disease characterized by hepatitis, pneumonia, and cerebral vasculitis. Salmonella typhimurium, S typhisuis, and several other species affect the GI tract primarily. Infection of the intestine results in necrotizing, nonsuppurative inflammation of the mucosa-submucosa of the ileum, cecum, and colon; frequently the mucosa is ulcerated. Usually, there is extension to regional lymph nodes and, occasionally, generalized septicemia. Sources of infection include carrier pigs, rodents, and contaminated feed and premises.

C620 Coccidiosis

A usually acute invasion and destruction of intestinal mucosa by protozoa of the genera Eimeria, Isospora, Cystoisospora, or Cryptosporidium, characterized by diarrhea, fever, inappetence, weight loss, emaciation, and sometimes death. Coccidiosis is a serious disease in cattle, sheep, goats, pigs, poultry, and also rabbits, in which the liver as well as the intestine can be affected. In dogs, cats, and horses, it is less often diagnosed but can result in clinical illness. Under modern husbandry conditions (off-floor housing), it is rarely a problem in mink. Other species, both of hosts and of protozoa, are involved. Coccidiasis is the infection of animals with coccidia but without apparent clinical signs. Coccidiasis is much more prevalent than coccidiosis and is thought to result in poor feed efficiency under intensive rearing conditions.

C621 Distomatosis (liver fluke)

Fasciola hepatica, the most important trematode of domestic ruminants, is the most common cause of liver fluke disease in temperate areas of the world. In the USA, it is endemic along the Gulf Coast, the West Coast, the Rocky Mountain region, and other areas. It is present in eastern Canada, British Columbia, South America, and is of particular economic importance in the British Isles, western and eastern Europe, Australia, and New Zealand. Fasciola gigantica is economically important in Africa and Asia, and is found in Hawaii. Fascioloides magna has been reported in at least 21 states (USA) and in Europe. In North America, Dicrocoelium dendriticum is confined mainly to New York, New Jersey, Massachusetts, and the Atlantic provinces of Canada. It is also found in Europe and Asia. Eurytrema spp, the pancreatic flukes, parasitize sheep, pigs, and cattle in Brazil and parts of Asia. Several species of paramphistomes or rumen flukes are found throughout much of the world.

C622 Filariasis

C630 Mastitis

A septic or nonseptic inflammatory process involving one or more mammary glands, which usually occurs during lactation. Septic mastitis may occur via an ascending infection from the nipples, penetrating wounds, or hematogenous spread.

C652 Mucosal disease/Bovine virus diarrhoea

An infectious disease of cattle caused by a pestivirus (family Togaviridae). The infection is usually subclinical or mild with high morbidity and low mortality, but severe disease with high mortality also occurs. BVD virus is immunosuppressive and may predispose to, or exacerbate, outbreaks of concurrent disease.

C653 Vibrionic dysentery

Campylobacter jejuni infection in cattle has been associated with enteric disease for over 50 years and was previously considered to be the cause of 'winter dysentery', a profuse watery diarrhoea of sudden onset and short duration in adult cattle. It now seems that 'winter dysentery' is caused by a coronaviral infection. Campylobacter jejuni has been isolated so frequently from the intestine of healthy animals that it is considered to be part of the normal intestinal flora. It is, however, possible that C. jejuni, either alone or in combination with other pathogens, may be involved in the development of a self-terminating enteritis in calves and sheep, but its significance in such cases should be interpreted with care. Campylobacter jejuni is also an occasional cause of mastitis and abortion in cattle, of abortion in sheep, and of abortion storms in goats and blesbok (Damaliscus dorcas). Campylobacter jejuni is a primary enteric pathogen of humans and an important zoonosis which arises primarily from deficiencies in hygiene. Statistics on the prevalence of C. jejuni infections in animals and humans in South Africa are not available, as it is not a notifiable disease. In contrast to other countries, where the organism and its effects are very prevalent in the more affluent sectors of society, in South Africa it appears to be more prevalent in the lower socio-economic groups.

C654 Warble infestation

Dermatobia hominis: The tropical warble fly or torsalo, one of the most important parasites of cattle in Latin America, is distributed between southern Mexico and northern Argentina. Larval stages are found in many hosts: cattle, sheep, goats, pigs, buffaloes, dogs, cats, rabbits, and man. Cattle and dogs are infected most commonly.

Hypoderma spp: Two species of Hypoderma, H. bovis and H. lineatum, are important pests of cattle. They occur between 25/ and 60/ latitude in the Northern Hemisphere, in more than 50 countries in North America, Europe, Africa, and Asia. In North America, H. lineatum, the common cattle grub, is found in Canada, the USA, and Northern Mexico; H. bovis, the northern cattle grub, is found generally north of the 35th parallel. Occurrence in cattle and American bison is common. Larvae of Hypodermia spp also have been reported in horses, sheep, goats and man.

C701 Contagious pustular dermatitis

(Contagious ecthyma, Sore mouth, Orf)

An infectious dermatitis of sheep and goats, affecting primarily the lips of young animals. Encountered in all parts of the world, it is most common in late summer, fall, and winter on pasture, and in winter in feedlots. The condition may occur in young lambs in early spring and occasionally in mature sheep that do not have immunity from natural exposure. Man is occasionally affected, and the disease has been reported in dogs that have eaten infected carcasses. The causal poxvirus (a parapoxvirus) is related to those of pseudo-cowpox and bovine papular stomatitis. Infection occurs by contact. The virus is highly resistant to desiccation, having been recovered from dried crusts after 12 yr. It is also resistant to glycerol and to ether.

C702 Foot-rot

A specific, chronic, necrotizing disease of the epidermis of the interdigital skin and hoof matrix. It commences as an interdigital dermatitis and extends to involve large areas of the hoof matrix. Because the infected tissue is destroyed, the hoof loses its anchorage and becomes detached. Foot rot is contagious and, under suitable conditions, morbidity may approach 100%. The infection is also found in goats and deer, but rarely in cattle. Foot rot is due to a mixed infection in which synergism between 2 gram-negative, anaerobic bacteria is essential. Fusobacterium necrophorum is a normal resident of the sheep's environment, but infection depends on the presence of Bacteroides nodosus, a strict parasite that does not survive for more than a few days in the soil or pastures. Because the prolonged availability of B nodusus depends on the presence of infected animals, it is regarded as the transmissible and specific causal agent of foot rot, although its contribution to the disease process is not necessarily greater than that of F necrophorum.

C703 Contagious ophthalmia

(Infectious keratoconjunctivitis, Pinkeye, Infectious ophthalmia)

Infectious diseases of cattle, sheep, and goats characterized by blepharospasm, conjunctivitis, lacrimation, and varying degrees of corneal opacity and ulceration. The clinical syndromes in the 3 species are distinct and apparently are caused by species-specific agents. In cattle, Moraxella bovis is the most common cause, although infectious bovine rhinotracheitis (IBR) virus and a Mycoplasma have produced conjunctivitis and transient corneal opacity; the latter 2 agents may potentiate M bovis disease. In sheep, Neisseria ovis, rickettsiae, and mycoplasmas have been associated with keratoconjunctivitis. Although much of the syndrome in young goats is caused by Mycoplasma agalactiae, it also is caused by Moraxella capri and Mycoplasma conjunctivae.

C704 Enterotoxaemia

(Pulpy kidney disease, Overeating disease)

An enterotoxemia of sheep, less frequently of goats, and rarely of cattle. This is the classic enterotoxemia of sheep. It is worldwide in distribution and may occur in animals of any age. It is most common in the young, either <2 wk of age or in weaned lambs in feedlots, on a high-carbohydrate diet or, less often, on lush green pastures. The disease has been suspected in well-nourished beef calves nursing high-producing cows grazing lush pasture, and in sudden death syndrome in feedlot cattle, but supportive laboratory evidence in the latter is lacking. Etiology: The causative agent is Clostridium perfringens type D. However, predisposing factors also are essential.

C705 Caseous lymphadenitis

A caseous abscessation of lymph nodes and internal organs caused by Corynebacterium pseudotuberculosis. The disease occurs worldwide and is an important endemic infection in regions with large sheep and goat populations. Economic losses result from reduced weight gain, reproductive efficiency, and milk production, as well as from condemnation of carcasses and devaluation of hides. Although principally an infection of sheep and goats, sporadic disease also occurs in horses and cattle, and water buffalo, wild ruminants, primates, pigs, and fowl. It rarely causes regional lymphadenitis in man.

C706 Sheep mange

In sheep, these diseases are caused by Sarcoptes scabiei var ovis, Chorioptes bovis, Psoroptes ovis, P. cuniculi, Demodex sp, and Psorergates (Psorobia) ovis. Sarcoptic mage in sheep occurs only on the nonwooly skin, starting, as a rule, on the head and face; it is rare. Chorioptic mange, the most frequent type in sheep, is most often found on the hindlegs and between the toes, or on the scrotum of rams; it is common;y called "leg" or "foot mange". Psoroptic scabies (sheep scab) is a notifiable disease: see B170. Demodectic mange has been reported in sheep and goats, in which it causes skin lesions similar to those in other large animals. "Itch mite" infestation: An infestation of sheep by Psorergates (Psorobia) ovis in which the pruritis induced by the mite causes the host to bite and rub the affected areas and to damage the fleece. The disease has been reported from Australia, New Zealand, South Africa, the USA, Argentina, and Chile, but it is not regarded as being of major economic importance. (Please take note that sheep scab (Psoroptic mange) is being reported under code: B170).

C720 Goat mange

Psoroptic mange (P cuniculi) of goats usually infests the ears but sometimes spreads to the head, neck, and body and causes severe irritation. This occurs particularly in Angora goats, in which the mohair is considerably damaged. Psoroptes cuniculi also infects the ears and sometimes the body of domestic rabbits. Demodectic mange has been reported in sheep and goats, in which it causes skin lesions similar to those in other large animals. In goats, it is similar to that of dairy cattle. The lesions are found on the skin of the neck, shoulder, thorax and flank.

C751 Equine coital exanthema

A benign venereal disease of horses. The disease occurs worldwide. It affects both sexes and is primarily spread at coitus; although rare in unmated horses, transfer by gynecological manipulations is possible. Abortion under natural conditions has not been substantiated. Immunity is short-lived. The causal equine herpesvirus 3 (EHV-3) is of one antigenic type, but a mixed population of small and large plaque variants can be isolated from clinical specimens.

C752 Ulcerative lymphangitis

In horses, Corynebacterium pseudotuberculosis causes ulcerative lymphangitis, an infection of the lower limbs, and chronic abscesses in the pectoral region.

 

C753 Strangles

An infectious, transmissible, worldwide disease of Equidae, characterized by inflammation of the upper respiratory tract and most often by abscessation of the adjacent lymph nodes. The causal agent is Streptococcus equi.

C754 Salmonellosis (Salmonella abortus equi)

Equine disease caused by the non-host-specific salmonellas (most commonly Salmonella typhimurium) occurs in many countries and is diagnosed sporadically in South Africa. Although infection with the host-specific Salmonella abortus equi is often quoted as a cause of abortion in mares, this only seems to be a problem in India, where other Salmonella serovars are also implicated in the syndrome. It has only been documented twice as being a cause of outbreaks of abortion in mares in the USA, and has not been reported there as a cause of abortion since the late 1960s. Salmonella abortus equi may also cause arthritis in foals and orchitis in stallions. Although Henning (1956) reported S abortus equi as the cause of purulent tendovaginitis, bursitis and pneumonia in horses in South Africa, it has not been isolated in the country since 1970.

C801 Swine erysipelas

An infectious disease mainly of growing pigs, common in many areas of the world. Although acute septicemic swine erysipelas causes death, the greatest economic loss probably occurs from the chronic, nonfatal forms of the disease. On farms where the organism is endemic, pigs are exposed naturally to Erysipelothrix rhusiopathiae when they are young; their maternal antibodies provide a degree of active immunity without visible disease. The organism is excreted by infected animals and survives for short periods in most soils. Recovered animals and those chronically infected may be carriers of the organism, possibly for life. Erysipelothrix rhusiopathiae was thought to cause an allergic reaction in the joints of sensitized pigs that resulted in chronic, sterile lesions similar to those observed in rheumatoid arthritis in man; this belief is now questioned.

C851 Infectious coryza

An acute or subacute respiratory disease of worldwide distribution characterized by nasal discharge, sneezing, and swelling of the face under the eyes. It is quite important in tropical and temperate climates. Although it also occurs in pheasants, guinea fowl, and turkeys, the disease is primarily one of chickens, mainly of older growing pullets and young layers; it is occasionally seen in broilers in tropical climates. It is present in "backyard flocks" and "fancy breed" establishments throughout the USA, and in commercial flocks in California and the southeast. The causative bacterium, (Haemophilus paragallinarum (gallinarum).

C853 Avian encephalomyelitis

(Epidemic tremor)

A worldwide viral disease of Japanese quail, turkeys, chickens, and pheasants, marked by ataxia and tremor of the head, neck, and limbs. Ducklings, pigeons, and guinea fowl are susceptible to experimental infection. The causative picornavirus can be grown in chicken embryos from nonimmune hens. It is transmitted for ~1 wk through a portion of eggs laid by infected hens, and then spreads laterally in the hatcher or brooder to susceptible hatch-mates.

C854 Avian spirochaetosis

(Avian borreliosis)

An acute, febrile, septicemic, bacterial disease of a wide variety of birds. The causal organism, a blood-inhabiting, actively motile spirochete, Borrelia anserina, is ~0.2-0.3 Fm wide and 8-20 Fm long and consists of 5-8 loosely arranged coils. No reliable data are available concerning in vitro cultivation. It can be propagated in embryonating duck or chick embryos, or young ducks or chicks. The disease is found worldwide, but generally in temperate or tropical regions, wherever the biological vectors are found. The notable worldwide vector is Argas (Persicargas) persicus, the "cosmopolitan" fowl tick, but other Argas spp transmit the disease in different geographic areas. In the western USA, a highly efficient vector is A (P) sanchezi.

C855 Avian salmonellosis (excluding B308 and B313)

These may be divided into those caused by: 1) 2 Salmonella spp highly host-adapted to the chicken and turkey (S pullorum (B313) and S gallinarium(B308)); 2) S arizonae, containing a few serotypes coomonly called paracolons; important in turkeys and, in a few countries, in chickens; and 3) the remaining ~ 2000 nonhost-adapted species. The latter group (paratyphoid) may be transmitted to almost all aniamls. Salmonellosis have major public health significance because contaminated food can infect man.

C856 Avian leukosis

Lymphoid leukosis occurs naturally only in chickens. Experimentally, some of the viruses of the leukosis/sarcoma group can infect and produce tumors in other species of birds or even mammals. The infection is known to occur in virtually all chicken flocks except for some SPF flocks from which it has been eradicated. The frequency of infection recently has been reduced substantially in the primary breeding stocks of several commercial poultry breeding companies. Should this control program continue, infection may become infrequent or totally absent in certain commercial flocks. The frequency of lymphoid leukosis tumors in infected flocks is typically low (<4%); disease is often inapparent. Etiology: The disease is caused by certain members of the leukosis/sarcoma group of avian retroviruses. Isolates that can induce lymphoid leukosis in chickens are commonly called avian leukosis viruses, and belong to subgroups A, B, C, and D. Subgroups A and B are most prevalent in western countries. A fifth subgroup (E) designates nononcogenic endogenous viruses produced by viral genes integrated into the host cell DNA. The subgroups have distinct antigenicities and cellular host ranges that are determined by viral envelope glycoproteins. Viruses within a subgroup cross-neutralize to varying extents. All field strains of lymphoid leukosis virus are oncogenic, although some differences in oncogenicity and replicative ability have been recognized.

C921 Canine distemper

(Hardpad disease)

A highly contagious, systemic, viral disease of dogs seen worldwide; it is characterized by a diphasic fever, leukopenia, GI and respiratory catarrh, and frequently, pneumonic and neurological complications. The disease occurs in Canidae (dogs, foxes, wolves), Mustelidae (eg, ferret, mink, skunk), most Procyonidae (eg, raccoon, coati mundi), and some Viveridae (binturong). Although it has been speculated that canine distemper virus causes multiple sclerosis in man, there is no supportive evidence. Unjustified concern has been expressed over human contact with dogs vaccinated with measles virus. Attenuated measles virus is used to protect dogs against distemper, but dogs do not shed the virus after vaccination.