Actinobacillosis is caused by several species of gram-negative coccobacilli of the genus Actinobacillus. Clinical signs vary, depending on the specific bacteria and the animal species they infect. Diagnosis can be confirmed by culture, PCR, or ELISA of tissue samples to identify the bacteria. Antibiotics are the usual treatment in swine and horses. Sodium iodide is used in ruminants, although antibiotics or surgical debulking may be required in severe or refractory cases.
Actinomyces are gram-positive, anaerobic bacteria that cause disease primarily in cattle and swine but also occasionally in other animals. Lumpy jaw is a localized, chronic, progressive, granulomatous abscess that most frequently involves the mandible, the maxillae, or other bony tissues in the head. Presumptive diagnosis is often based on clinical signs. The diagnosis can be confirmed by culture of the organism from the lesion; however, this requires anaerobic conditions and is frequently negative. The goal of treatment for actinomycosis is to kill the bacteria and stop the spread of the lesion.
Amyloidosis is caused by deposition of insoluble proteins in tissue. Formation of the proteins is often associated with inflammation. Deposition can lead to organ dysfunction, which can be fatal if critical organs are affected. Diagnosis is based on tissue biopsy. There is no effective treatment once protein deposition has occurred, although reducing inflammation may slow the progression of the disorder.
Anthrax is a noncontagious zoonotic disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax primarily affects domestic and wild herbivores. Clinical features, characterized by sudden death, with leakage of uncoagulated blood from natural openings, overlap those of the hemorrhagic fevers, with hyperacute or acute onset of clinical signs. Common diagnostic tests include microscopic examination, culture, and PCR assay. The most effective control strategy for animals in endemic areas is vaccination. Antimicrobial therapy is effective if administered at an early stage. Control measures include proper disposal of carcasses, disinfection and decontamination of contaminated materials, and environmental decontamination.
Besnoitiosis, caused by tissue cyst–forming apicomplexan parasites of the genus Besnoitia, is usually a chronic and debilitating disease characterized by skin lesions and systemic clinical signs of varying severity. The disease compromises welfare and is responsible for severe economic losses: infected cattle may lose weight and have decreased milk production, dams may abort during the febrile stage, males may develop infertility or even sterility, and the hides of affected animals are of reduced value for leather production. Skin lesions and visible scleral tissue cysts characteristic of the chronic disease are similar in the different ungulate species affected. There are no effective treatments. For control in cattle, the only permitted vaccine worldwide is a live vaccine used to immunize imported bulls in Israel. Thus, control relies entirely on accurate diagnosis and herd management.
Chlamydiosis in animals ranges from subclinical infections to life-threatening infections, depend on the chlamydial species and infected host and tissues. Confirmation of chlamydial infection requires appropriate clinical samples and direct detection of the organism by use of an appropriate diagnostic test. Most treatment is based on tetracyclines, macrolides, and fluoroquinolones.
Clostridia are prokaryotic bacteria of the phylum Firmicutes, which are large, anaerobic, spore-forming, rod-shaped, gram-positive organisms. They can be living cells (vegetative forms) or dormant spores. Their natural habitats are soils and intestinal tracts of animals, including humans.
Embryonic and fetal development are the result of a complex series of well orchestrated events. When properly accomplished, the outcome is a healthy neonate. Errors in the sequential steps of development may be followed by:
Coxiellosis is a zoonotic infection with Coxiella burnetii, which most commonly results in abortions in ruminants. Prevalence is high in commercial cattle and dairy populations; the organism is spread through environmental contamination by aborted tissues, urine or feces. Many infected animals and humans have no clinical signs, but some people experience serious illness, known as Q fever. Coxiellosis is managed by vaccination where available, segregation of infected animals, and preventative measures for human caretakers of infected animals.
Erysipelothrix rhusiopathiae is an opportunistic bacterial pathogen that primarily affects swine, turkeys, and sheep. In swine, it causes erysipelas, which takes forms ranging from acute septicemia to subacute cutaneous erythema—including classic, diamond-shaped lesions—to chronic arthritis or endocarditis. In turkeys, erysipelas also has a range of clinical signs but primarily manifests as cyanotic cutaneous lesions, including blue comb, and muscular petechiae. E rhusiopathiae infection in sheep is most commonly seen as nonsuppurative polyarthritis in growing lambs over a month of age. As a zoonosis, erysipeloid in humans is generally an occupational disease characterized by localized cutaneous lesions and rarely septicemia. The bacterium can infect a wide range of host species, and disease is newly emerging in wildlife. Diagnosis is based on clinical signs, isolation of the bacteria, and PCR. Treatment with antibiotics is generally effective in acute cases, and prevention through vaccination is effective at controlling outbreaks in swine.
Foot-and-mouth disease is one of the world's most economically important viral diseases of livestock. The virus infects cattle, pigs, and sheep and many cloven-hoofed wildlife species. The infection results in vesicular lesions in and around the mouth and on the feet, resulting in the reluctance of an animal to eat or move. Confirmation of the infection requires laboratory analysis, usually involving real time RT-PCR, and serotyping is achieved using antigen ELISA. Inactivated virus vaccines are available.
Systemic mycoses are infections with fungal organisms that exist in the environment, enter the host from a single portal of entry, and disseminate within the host usually to multiple organ systems. The soil reservoir is the primary source of most infections, which can be acquired by inhalation, ingestion, or traumatic introduction of fungal elements. (Also All.see page Dermatophilosis.)
Leptospirosis is a zoonotic disease with a worldwide distribution caused by infection with any of several pathogenic serovars of Leptospira. The disease affects virtually all mammals and has a broad range of clinical effects, from mild, subclinical infection to multiple-organ failure and death. Kidney, liver, and respiratory disease are key findings. Diagnosis is best made by a combination of serologic testing and PCR assay. Antimicrobial therapy is usually effective; however, organ damage can be permanent.
Injury or death from electrocution may be caused by lightning, fallen power lines, faulty electric circuits, or other causes. Death usually results from cardiac or respiratory arrest. Besides sudden death, signs can include singe marks, temporary loss of consciousness in mild cases, and fractures or muscle damage from severe contractions. Diagnosis may depend on circumstantial evidence, such as the location of groups of affected animals and lack of other signs of disease. For animals that survive the initial event, supportive care is indicated.
The most common clinical manifestation of listeriosis is a localized ascending asymmetric infection of the brain stem of ruminants by Listeria monocytogenes. The resultant meningoencephalitis damages the origins of cranial nerves V, VII, and VIII in the brain stem, resulting in unilateral facial paresis or paralysis, head tilt, loss of sensation, depression, and recumbency. Diagnosis in ruminants is based on typical neurologic clinical signs. Treatment with high dosages of antimicrobials may be effective if given early in the course of infection.
Lyme borreliosis is a vector-borne zoonotic disease transmitted by ticks infected with spirochetal bacteria belonging to the genus Borrelia. Affected dogs typically present with intermittent, lameness, fever, inappetance, lethargy, and focal lymphadenopathy. Although infrequently reported, clinical manifestations in horses include neurologic abnormalities, uveitis, and cutaneous lymphoma. Diagnosis is based on a combination of history, clinical signs, laboratory findings, exclusion of other diseases, and response to treatment. Treatment consists of an extended (eg, 30-day) course of antibiotics, supportive measures including analgesia, and immunosuppressive therapy in the case of autoimmune reaction.
Melioidosis is a disease of humans and animals, caused by a soil-borne Gram-negative bacteria endemic to Australia and southeast Asia. Clinical signs are widely variable as infection can occur in any tissue; the most common manifestations are sepsis, pneumonia and visceral abscesses. Morbidity and mortality are high, particularly when diagnosis and treatment are delayed.
Neosporosis is a disease caused by infection with protozoal parasites in the genus Neospora, most often N caninum but also N hughesi in horses. The most commonly observed problems include bovine abortion and gradually progressive myositis with paraparesis in puppies. Diagnosis is based on a combination of clinical signs, histopathology, serology, and PCR. There are no approved treatments in cattle, but antibiotics may be helpful in dogs.
Nocardia is a genus of widely distributed saprophytic bacteria that can cause opportunistic cutaneous/subcutaneous or pulmonary infections in domestic animals, wildlife, and humans following inoculation or inhalation, which can progress to systemic disease. Characteristic histologic or cytologic findings include suppurative to pyogranulomatous inflammation with branched, filamentous organisms with gram-positive and partially acid-fast staining characteristics. Special microbiological techniques and molecular diagnostic testing may be necessary for confirmation. Many months of targeted antimicrobial therapy based on culture and susceptibility results may be required. Prognosis is guarded in cases of disseminated disease.
Peritonitis is the inflammation of the serous membranes of the peritoneal cavity. It may be primary or caused by infectious or noninfectious agents. Signs include localized pain, depression, fever, and anorexia. The clinical diagnosis may be supported by ultrasonography and laboratory analysis of blood or abdominal fluid. Treatment may include peritoneal lavage, surgery, antibiotics, and anti-inflammatory medications.
Plague, caused by Yersinia pestis, is an acute and sometimes fatal bacterial zoonosis transmitted primarily by the fleas of rats and other rodents. Enzootic foci of sylvatic plague exist in the western USA and throughout the world, including Eurasia, Africa, and North and South America. In addition to rodents, other mammalian species that have been naturally infected with Y pestis include lagomorphs, felids, canids, mustelids, and some ungulates. Domestic cats and dogs have been known to develop plague from oral mucous membrane exposure to infected rodent tissues, typically when they are allowed to roam and hunt in enzootic areas. Birds and other nonmammalian vertebrates appear to be resistant to plague. On average, 10 human plague cases are reported each year in the USA; most are from New Mexico, California, Colorado, and Arizona. Most human cases result from the bite of an infected flea, although direct contact with infected wild rabbits, rodents, and occasionally other wildlife and exposure to infected domestic cats are also risk factors.
Protothecosis is an infection caused by members of the genus Prototheca (achlorophyllous algae found ubiquitously in the environment). Prototheca organisms are opportunistic and infect humans, some domestic animals, and wildlife. Mammary infections in cattle, cutaneous lesions in cats, hemorrhagic enteritis and systemic signs in dogs, and cutaneous, articular, and disseminated infections in humans represent the main clinical manifestations. The algae usually are refractory to conventional therapy.
Rhodococcus infection causes pyogranulomatous disease, typically suppurative pneumonia, lymphadenitis, and abscesses in other organs, and affects both animals and humans. It is caused by Rhodococcus equi (formerly Corynebacterium equi), an opportunistic, ubiquitous soilborne bacterium. It is found worldwide and is a pathogen of major importance to equine breeding activities.
Seneca Valley virus disease is a viral vesicular disease of pigs caused by a picornavirus related to the viruses that cause foot-and-mouth disease and swine vesicular disease. Clinically affected pigs develop cutaneous vesicular lesions, mainly on the snout and coronary bands. Seneca Valley virus disease is important as a differential diagnosis for high-consequence transboundary animal diseases, including foot-and-mouth disease, swine vesicular disease, and vesicular exanthema of swine, from which it is clinically indistinguishable.
Sweating sickness is an acute, febrile, tickborne toxicosis characterized mainly by a profuse, moist eczema and hyperemia of the skin and visible mucous membranes. It is essentially a disease of young calves, although adult cattle are also susceptible. Sheep, pigs, goats, and a dog have been infected experimentally. It occurs in eastern, central, and southern Africa and probably in Sri Lanka and southern India.
Toxoplasmosis is an important zoonotic protozoal infection worldwide. All homoeothermic animal species may be infected. Infection is generally asymptomatic and chronic in immunocompetent individuals. Common clinical signs are abortion and reproductive failure, especially in small ruminants, cervids, and pigs. Some susceptible animal species (e.g., Australian marsupials, New World monkeys, and meerkats), as well as immunocompromised individuals, suffer multiorgan failure, referred to asfatal toxoplasmosis. Humans may experience retinochoroiditis (ocular toxoplasmosis) or fetal neurologic disorders (congenital toxoplasmosis). Monitoring by means of serologic testing and anticoccidial treatments is recommended.
Tuberculosis is an infectious zoonotic disease caused by Mycobacterium tuberculosis and Mycobacterium avium complex. It is usually a chronic, debilitating disease; however, symptoms vary across species. Diagnosis is based on the cellular immune response and identification of the organism by culture or molecular tests. Treatment relies on a prolonged course of a cocktail of antimicrobials and is often not attempted in animals, because of public health concerns.
Most of the Overview discussion applies to bovine tuberculosis, which is caused predominantly by M bovis. The introduction of milk pasteurization was a major step in the fight against infection by Mycobacterium tuberculosis complex in cattle and humans, and pasteurization continues to be an important control procedure in many countries where the disease is present. Many countries have eradicated or controlled bovine TB through test-and-cull and abattoir surveillance programs.
Tularemia is a bacterial septicemia that infects >250 species of wild and domestic mammals, birds, reptiles, fish, and people. It is listed as a category A bioterrorism agent because of the potential for fatality, airborne dissemination, and societal disruption if released. Clinical signs depend on the host species, subspecies of bacteria, and route of infection. Diagnosis is confirmed by culture, serology, or PCR. Antibiotic treatment can be effective if begun early.
Vesicular stomatitis (VS) is a viral disease of livestock transmitted primarily by biting flies and midges. The disease results in characteristic vesicular lesions that can occur on the muzzle, lips, tongue, ears, sheath, udder, ventral abdomen, and/or coronary bands. The disease is generally self-limiting, with no specific treatment, but some animals may require supportive care. VS is a reportable disease in most countries, including the United States, with diagnostic confirmation by complement fixation test, PCR, and/or virus isolation at an approved reference laboratory. In ruminants and swine, the disease is clinically indistinguishable from foot-and-mouth disease, swine vesicular disease, and vesicular exanthema of swine, which must be ruled out first on diagnostic testing. Vesicular stomatitis virus is zoonotic and can be transmitted to humans through direct contact with lesioned animals, so personal protective measures should be used when handling infected livestock.
African horse sickness (AHS) is a life-threatening hemorrhagic disease of equids characterized by respiratory and circulatory impairment. It is caused by the AHS virus (AHSV), genus Orbivirus, family Reoviridae. It is transmitted by midges (Culicoides spp) and endemic to sub-Saharan Africa. Diagnosis is by real-time PCR assay. Control is centered around vaccination.
Equine granulocytic anaplasmosis is a febrile disease of horses caused by the tick-transmitted bacterium Anaplasma phagocytophilum. The disease can produce a high fever, which is responsive to tetracycline-class drugs. Equine and canine infections serve as sentinels for human risk because the same tick species can transmit the pathogen to any of these host species.
Equine infectious anemia (EIA) is a noncontagious infectious disease of equids caused by a virus of the same name. Clinical outcomes range from subclinical to a range of signs of variable severity, including fever, depression, muscle weakness, thrombocytopenia, anemia, jaundice, increased heart and respiration rates, hemorrhages on mucous membranes, epistaxis, collapse, and death in a small percentage of cases. Diagnosis of EIA is based on serologic testing and demonstration of antibodies to the virus in blood. There are no treatments or vaccines.
Equine viral arteritis (EVA) is an economically important, contagious, viral disease of equids caused by equine arteritis virus (EAV). Exposure to EAV may result in clinical or more frequently, asymptomatic infection, depending on the virus strain, host genetic factors, and various management and environmental factors. EAV infection can cause abortion, respiratory illness, establishment of a carrier state in stallions, and interstitial pneumonia and death in young foals. Diagnosis of EVA is based on virus detection in body secretions or fluids, whole blood, or tissues by virus isolation, RT-PCR and in situ hybridization; identification of viral antigen in tissues; and detection of viral-specific antibodies by serology. The treatment of EVA is general supportive care during the acute phase of infection. There is no treatment to eliminate persistent infection in stallions. Attenuated and inactivated vaccines are available in North America and Europe, respectively, for prevention and control.
Glanders, an often fatal contagious disease of solipeds, now found in remote areas of the world, is caused by Burkholderia mallei. The disease is characterized by purulent nasal discharge, nasal mucosal ulceration, lung lesions, and ulcerating nodules along the subcutaneous lymphatics. Diagnosis is based on presence of nasal ulcers, complement fixation test reaction, positive mallein test, and culture and PCR. Control is based on isolation and culling of affected animals.
Hendra virus infection is a viral disease that can cause acute fatal respiratory and/or neurologic signs in horses of all ages. People and dogs have been infected as spillover events from close contact with clinically infected horses. Diagnosis can be accomplished by viral isolation, PCR, or serology. There is no effective treatment for clinically infected animals, although a vaccine can prevent clinical disease in horses.
African swine fever (ASF) is a highly infectious and severe hemorrhagic disease of pigs that produces a wide range of clinical signs and lesions that can closely resemble those of classical swine fever. African swine fever virus (ASFV) has a case fatality rate of up to 100% in domestic pigs and wild boar. The virus is enzootic in many African countries, where it is maintained in the environment through a sylvatic cycle involving warthogs and Ornithodoros (soft) ticks. In 2007, ASFV spread from Africa to Georgia and has since spread to many countries across Northern and Eastern Europe, Russia, and Asia, including China, which produces over half of the world's pork. This outbreak has resulted in the death and slaughter of millions of pigs, posing a massive threat to the global pig industry. There is currently no effective vaccine.
Classical swine fever (CSF) is a highly contagious and often fatal viral disease of swine. Infected pigs develop fever, hemorrhages, lethargy, yellowish diarrhea, vomiting, and a purple skin discoloration of the ears, lower abdomen, and legs. Neurologic signs, reproductive failures, and abortion may also be observed. Diagnostic tests for CSFV detection include RT-qPCR, virus isolation, immunofluorescence assay, and detection of antibodies by serologic tests such as ELISA and virus neutralization. There are no treatments for CSFV. Instead, vaccination against CSFV is used to prevent the disease and is usually applied in regions of the world where CSF is endemic. Countries considered free of the disease do not apply vaccination (eg, USA, Canada, and Europe).
Edema disease is a syndrome of peracute vasculitis causing facial swelling, enteritis and sometimes focal encephalomalacia in post-weaning pigs. The causative agent is F18+ E coli. The disease is characterized clinically by visible edema of the face and GI tract. Treatment is limited as the disease is rapidly fatal in most affected animals; prevention is aimed at vaccination and management strategies.
Encephalomyocarditis (EMC) is an important viral infection of feral rodents, swine, and captive zoo mammals. It is caused by members of the genus Cardiovirus in the family Picornaviridae and recognized in many parts of the world. The virus has been recovered from rats, mice, squirrels, voles, domestic and wild swine, raccoons, antelope, lions, elephants, birds, and various species of nonhuman primates. Infections in humans have also been reported.
Glässer disease is caused by infection with Glaesserella (Haemophilus) parasuis. The most common form is characterized by fibrinous polyserositis and polyarthritis, but septicemia with sudden death and bronchopneumonia also can occur. Diagnosis is based on clinical signs and bacterial isolation or PCR. Antibiotic treatment remains the first option to control a disease outbreak, but several vaccines are available for prevention.
Nipah virus disease is a relatively newly discovered disease of swine and humans caused by infection with a novel paramyxovirus termed Nipah virus. This disease emerged in Malaysia in 1998 and 1999. It was linked to severe encephalitis among people occupationally exposed to infected pigs in Malaysia and Singapore. The disease was eradicated from the national commercial swine population by control efforts. A number of fruit bats of the genus Pteropus seem to be reservoirs of the virus in Asia.
Porcine circoviruses have been associated with multiple disease conditions in pigs, including postweaning multisystemic wasting syndrome and reproductive disorders. Virus has been detected in all body secretions. Depending on the specific type of circovirus, signs may include weight loss, late-term abortions and stillbirths, and a necrotizing vasculitis. Control of PCV-2 is by vaccination.
Porcine hemagglutinating encephalomyelitis is a viral disease of piglets, characterized by a vomiting and wasting syndrome and/or encephalomyelitis. Although the virus is widespread, outbreaks are rare because sows pass protective antibodies during nursing. Diagnosis is suspected based on clinical signs and can be confirmed by viral isolation, immunofluorescence staining of tissues, or PCR. There is no treatment or vaccine. Control is focused on building immunity among breeding sows.
Porcine reproductive and respiratory syndrome is a viral disease first reported in 1987 in the USA and now found throughout North and South America, Asia, Africa, and Europe. There are two distinct clinical phases: reproductive failure and postweaning respiratory disease. Diagnosis is by serology or PCR. There are no effective treatments, although modified-live vaccines provide partial protection against infection.
Of the bacterial group of gram-positive cocci comprising the genera Streptococcus, Enterococcus, and Peptostreptococcus, streptococci constitute the most significant pathogens of swine. Streptococci are also associated with infectious conditions of people, cattle, sheep, goats, and horses. Relative to pigs, S suis (an alpha-hemolytic Streptococcus) is by far the most important agent of infectious diseases in this group, affecting mainly nursing and recently weaned pigs. Septicemia, meningitis, polyserositis, polyarthritis, and bronchopneumonia are associated with S suis infections.
Swine vesicular disease is a viral vesicular disease of pigs caused by an enterovirus closely related to human coxsackie virus B5. It is generally a mild disease that was endemic in Italy until recently; it has occurred only sporadically in other countries. Its importance is as a differential diagnosis for foot-and-mouth disease, from which it is clinically indistinguishable.
Trichinellosis is a zoonotic condition affecting mammals, including humans, birds and reptiles caused by infection with Trichinella sp. People are most commonly infected by eating improperly cooked pork. Whereas infection in animals is usually undetected and of minimal clinical importance, trichinellosis is an important human public health risk globally. Prevention of disease in people is accomplished via appropriate meat inspection practices and proper cooking or freezing of meat and meat products.
Vesicular exanthema of swine (VES) is an acute, highly infectious disease characterized by fever and formation of vesicles on the snout, oral mucosa, soles of the feet, coronary bands, and between the toes.
Bluetongue is a viral disease of ruminants worldwide. Clinical signs in sheep result from vascular endothelial damage, including edema of the muzzle, tongue, and coronary bands. Diagnosis is made on clinical suspicion and viral identification. Control and prevention measures consist of vaccination, where available, and vector control.
Bovine ephemeral fever is an arthropod-borne viral disease of cattle and water buffalo that causes milk production losses, recumbency, and sometimes death. Diagnosis is mostly performed by PCR. Treatment includes administration of NSAIDs, accompanied by supportive care to recumbent cows. Vaccine effectiveness varies.
Bovine leukosis is caused by an oncogenic retrovirus of cattle. Most animals remain asymptomatic despite becoming persistently infected by the virus, but a proportion of cattle will develop lymphosarcoma. Clinical signs are associated with the organ system that is affected by the solid tumor. Infected cattle can be identified using serology or PCR assay.
Bovine petechial fever is caused by the rickettsia Ehrlichia ondiri and affects cattle and some species of wildlife in the highlands of Kenya and Tanzania. Clinical signs include intermittent fever, depression, decreased milk production, and petechial hemorrhage affecting mucous membranes. Diagnosis is based on clinical signs and can be confirmed by histopathologic evaluation. Treatment with antimicrobials may be successful if started early in the course of disease.
Bovine viral diarrhea/mucosal disease is a pestivirus infection of cattle and other ruminants. Infection leads to immunosuppression and can cause signs in multiple body systems in addition to the digestive tract. Mucosal disease is an uncommon form of infection in persistently infected cattle and is typically fatal. Clinical signs range from inapparent infection to fever, depression, decreased milk production, abortion, diarrhea, and death. Diagnosis is based on clinical signs, virus isolation, serology, and PCR. Treatment consists of supportive care. Improved biosecurity and vaccines are used for prevention and control.
Caprine arthritis and encephalitis (CAE) is a persistent lentiviral infection of goats. There are multiple clinical presentations: 1) leukoencephalomyelitis, affecting 2- to 6-month-old kids, 2) chronic, hyperplastic polysynovitis, 3) indurative mastitis, and 4) interstitial pneumonia. Presence of caprine arthritis encephalitis virus (CAEV) can be confirmed in a goat herd by means of serologic testing; however, a positive result does not guarantee an individual animal will develop clinical signs of disease. A presumptive diagnosis is based on clinical signs. There is no vaccine or specific treatment for CAEV, supportive care is indicated, with euthanasia necessary in severe cases.
Colisepticemia is characterized by invasion of the blood stream by coliform bacteria and is primarily observed in neonates and immune-compromised animals. Affected animals show pronounced signs of systemic disease and tend to deteriorate rapidly. A presumptive diagnosis is made based on clinical signs in combination with hematologic and blood biochemical results. Blood cultures are considered a diagnostic gold standard, but they lack sensitivity, and results are not readily available. Therapy consists of immediate, thorough antimicrobial, anti-inflammatory, and fluid therapy.
Crimean-Congo hemorrhagic fever (CCHF) is a severe hemorrhagic disease affecting humans caused by the zoonotic CCHF virus. Many animal species and some birds can be infected without signs of illness in natural infection. Ticks are the main vector for human disease, as well as contact with blood or tissues of infected wild or domestic animals or that of other infected human patients.
Heartwater is an infectious, noncontagious, tickborne rickettsial disease of ruminants. The disease is seen only in areas infested by ticks of the genus Amblyomma. These include regions of Africa south of the Sahara and the islands of the Comores, Zanzibar, Madagascar, Sao Tomé, Réunion, and Mauritius. Heartwater was introduced to the Caribbean, and it and its vector (A variegatum) are endemic on the islands of Guadeloupe and Antigua. A variegatum, but not the rickettsia, has since spread to several other islands despite attempts at eradication. Possible spread to the mainland threatens the livestock industry of regions from northern South America to Central America and the southern USA. In heartwater endemic areas in southern Africa, it is estimated that mortalities due to the disease are more than double those due to bacillary hemoglobinuria (red water, All.see page Bacillary Hemoglobinuria in Animals) and anaplasmosis ( All.see page Anaplasmosis in Ruminants) combined. Cattle, sheep, goats, and some antelope species are susceptible to heartwater. In endemic areas, some animals and tortoises may become subclinically infected and act as reservoirs. Indigenous African cattle breeds (Bos indicus), especially those with years of natural selection, appear more resistant to clinical heartwater than B taurus breeds.
Infection by Histophilus somni is common in North American cattle and sporadic in other locations worldwide. Sudden death, or a variety of clinical signs dependent on the system affected, may be observed. Diagnosis is based on histopathology, bacterial isolation, and PCR. Because identification of infected animals is difficult early in the course of the disease, antibiotic treatment may not be successful. Multivalent bacterins may help reduce morbidity and mortality.
Hemorrhagic septicemia is a disease of water buffalo and cattle in tropical regions caused by specific serotypes of Pasteurella multocida. Asymptomatic, pneumonic, and disseminated (endotoxemic) forms occur, often with peracute distress and high mortality. However, antimicrobial treatment very early in disease can reduce mortality. Definitive diagnosis requires the isolation of P multocida serotypes B:2 or E:2 or detection by molecular capsular and somatic serotype assays.
Malignant catarrhal fever is a severe, often fatal, lymphoproliferative disease of artiodactyls caused by ruminant gammaherpesviruses. Clinical signs include fever, oral and nasal erosions, enlarged lymph nodes, and centripetal corneal opacity. Diagnosis is based on clinical signs and laboratory confirmation.
Nairobi sheep disease is a serious tickborne viral disease of small ruminants in Africa. It is characterized by peracute deaths and acute illness with severe hemorrhagic gastroenteritis. Ganjam virus, which circulates in Asia, is now considered a variant of the same virus. There is no specific treatment, and case fatality rates are high.
Pasteurellosis commonly refers to mixed, often secondary, bacterial infection of the lower respiratory tract due to Pasteurella multocida, Mannheimia haemolytica (formerly Pasteurella haemolytica), and Bibersteinia trehalosi. Preliminary diagnosis is suggested by history, clinical signs of bronchopneumonia, and gross lesions at necropsy; definitive diagnosis can be made via identification of the causative agent from transtracheal wash or bronchoalveolar lavage samples or postmortem lung lesions. Treatment includes appropriate antimicrobial administration initiated early in the disease course.
Peste des petits ruminants (PPR) is an acute or subacute viral disease of goats and sheep characterized by fever, necrotic stomatitis, gastroenteritis, pneumonia, and sometimes death. It was first reported in Cote d’Ivoire (the Ivory Coast) in 1942 and subsequently in other parts of West Africa. Goats and sheep appear to be equally susceptible to the virus, but goats exhibit more severe clinical disease. The virus also affects several wild small ruminant species. Cattle, buffalo, and pigs are only subclinically infected. People are not at risk.
Rift Valley fever is a peracute or acute mosquito-borne zoonotic disease of domestic and wild ruminants, largely confined to sub-Saharan Africa but with high potential for wider transmission. It is characterized by abortions and neonatal mortality in ruminant animals. Diagnosis depends on histopathological examination of samples of the liver and identification of the virus in tissues. Effective vaccines are available.
Rinderpest was the first animal disease to be globally eradicated. Because it was such a scourge and re-emergence remains a possibility, it is vital to maintain current information. Rinderpest was a viral disease of cattle and other ruminants (domestic and wild) characterized by fever, erosive stomatitis, diarrhea, and high morbidity and mortality. In the post-eradication era, testing for rinderpest, preferably using molecular methods, should be considered when an etiologic agent cannot be determined for an infectious disease with characteristic signs of rinderpest.
Tickborne fever is a rickettsial disease of domestic and free-living ruminants in the temperate regions of Europe. Disease is transmitted by the hard tick Ixodes ricinus. The main clinical signs are sudden fever in sheep and depression, weight loss and decreased milk yield in cattle. Diagnosis is by PCR. Oxytetracyclines are the most effective treatment. There is no vaccine.
Tick pyemia is mainly a staphylococcal superinfection of lambs already infected with Anaplasma phagocytophilum,the causative agent of tickborne fever. This results in the formation of crippling abscesses in joints and other parts of the body. Diagnosis is based on clinical signs, isolation of bacteria from lesions, and PCR. Penicillin or tetracycline can be used for treatment.
Wesselsbron disease is an acute, mosquito-borne viral infection of mainly sheep, cattle, and goats in sub-Saharan Africa that is associated with rainfall and flooding. Infection is common, but clinical signs are infrequent (though probably underreported). Newborn lambs and goat kids are the most susceptible, and mortality may occur. Infection in adult sheep, cattle, and goats is usually subclinical; however, it may cause abortion, congenital CNS malformation, arthrogryposis, and polyhydramnios.
Canine distemper is a highly infectious, systemic, viral disease of dogs that occurs worldwide. Dogs commonly exhibit systemic clinical signs (fever, lethargy, loss of appetite), respiratory signs (nasal discharge, pneumonia), and GI signs (diarrhea), variably followed by neurologic signs (muscle twitching, focal or generalized seizures), which may be delayed. Vaccination is available and is generally effective. Diagnosis is made by recognition of the clinical signs, along with confirmation through antibody assays or reverse transcriptase PCR. Treatment is generally supportive, and the prognosis varies with the severity of the neurologic signs.
Canine herpesvirus infection is a systemic viral infection that affects puppies worldwide, with mortality rates often reaching 100% in affected litters. Clinical signs, though severe, are nonspecific and can include anorexia, weight loss, inappropriate vocalization, blindness, abdominal distention, dyspnea or tachypnea, and diarrhea. For neonatal infections, treatment consists of nonspecific supportive care.
Feline infectious peritonitis (FIP) is an immune-mediated disease triggered by infection with a feline coronavirus (FCoV). FCoV belongs to the family Coronaviridae, a group of enveloped, positive-stranded RNA viruses frequently found in cats. Coronavirus-specific antibodies are present in as many as 90% of cats in catteries and in as many as 50% of those in single-cat households. However, <5% of FCoV-infected cats develop FIP in multicat households.
Feline leukemia virus (FeLV) is one of the most common infectious causes of disease of cats globally. Infection with FeLV can cause a variety of clinical signs, impacting a cat's longevity and quality of life. Vaccination and identification of infected cats is important in preventing disease transmission.
Feline panleukopenia is a parvoviral infectious disease of kittens typically characterized by depression, anorexia, high fever, vomiting, diarrhea, and consequent severe dehydration. Adult cats are much less often affected. Diagnosis is usually based on clinical signs, severe neutropenia and lymphopenia, and fecal viral antigen or PCR testing. Treatment includes intensive fluid therapy, glucose and potassium supplementation, antimicrobial, anthelmintic, and antiemetic therapy, and sometimes immunotherapy.
Adenoviral hepatitis in dogs results in fever, vasculitis and hepatitis, with possible sequelae of coagulopathy and subsequent immune-mediated corneal or renal effects. Most dogs recover but the disease can be fatal. Treatment is supportive; ante-mortem diagnosis is by PCR, ELISA or serology. Vaccination with modified live canine adenovirus-2 is protective against this disease caused by canine adenovirus-1, and is considered a core vaccine.
The leishmaniases are spectral diseases caused by protozoan parasites of the genus Leishmania. Key signs range from localized cutaneous lesions to lymphadenopathy and renal failure for visceral disease. Diagnosis is often made via serology, with quantitative serologic tests such as immunofluorescence assays or ELISA as confirmation. Treatment options are limited by World Health Organization guidelines in human disease endemic areas and by drugs that are FDA-approved within the USA, but include combination use of allopurinol with miltefosine, or liposomal amphotericin B within the USA, and glucantime internationally.
Ehrlichiosis is a tick-transmitted disease that infects blood cells and can cause a variety of signs from none to fever and generalized achiness to possible fatality. Several species of bacteria cause ehrlichiosis, and some of the species infect humans as well as animals such as dogs. Diagnosis is based on signs, serology, and PCR. Doxycycline is the treatment of choice.