Brucella suis is the causative agent of brucellosis in swine, rabbits, reindeer, and caribou. 1,2,6,9,17,18 Brucella suis has also been reported to infect dogs, horses, humans, and cattle but has been considered a noncontagious disease in nonprimary hosts. 1 The number of B. suis isolates from bovine tissue and/or milk confirmed or identified at the National Veterinary Services Laboratories (NVSL) varied from 5 in 1986 to a high of 15 in 1991. Most of these isolates were from animals in the swamp areas of the southeastern United States, especially southern Florida. A large population of feral swine are located in the same area as the B. suis-infected cattle. Approximately 25% of the feral swine are seropositive for brucellosis. 20 Little information about the disease process produced by B. suis biovar 1 in cattle has been reported. 9,17 The purpose of this study was to examine the bacterial, serological, and histological effects of B. suis in naturally infected cattle.Six cows (1-6) naturally infected with B. suis biovar 1 and 1 calf (2A) from cow 2 were obtained from 4 southern Florida counties (Brevard, Hardee, Hendry, and Osceola). Two serologically negative, nonvaccinated cows (7 and 8) and a serologically negative bull (9) were included as control animals to monitor transmission. Six calves (2B, 3A, 4A, 5A, and 6A) were born to the infected cows in the study, and 4 calves (7A, 7B, 8A, and 8B) were born to the control cows during the study. All animals, including the calves, were kept together in an animal biosafety level 2 facility at the NVSL. After 2 years, tissue and serum samples were collected at necropsy from all the animals in the study except for the offspring of the 2 control cows, cultured for Brucella, and tested for Brucella antibodies.Heparinized blood samples, vaginal swabs, and quarter milk samples were collected from the cattle biweekly and cultured for Brucella. 13 Serum samples and quarter milk samples were evaluated for the presence of Brucella antiFrom the US Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services, National Veterinary Services Laboratories, Ames, IA 50010.Received for publication December 6, 1995. bodies. 3 Placentas were collected and cultured for Brucella at the time of parturition. The following tissues were collected from the cows at necropsy: lymph nodes (pharyngeal, prescapular, mammary or scrotal, parotid, mandibular, bronchial, internal and external iliac, mesenteric, lumbar, and hepatic), mammary gland, spleen, lung, uterus, ovary, kidney, liver, epididymis, and testicle. A portion of each tissue specimen was processed and inoculated on selective media for Brucella, and the remainder was placed in 10% neutral buffered formalin and routinely processed for histopathologic examination. Brucella isolates were identified by the approved methods. 4 Sera were tested for Brucella antibodies by the following tests: card, buffered acid plate antigen (BAPA), complement fixation (CF), mercaptoethanol (ME), standard plate agglutination (...
Abstract. An enzyme-linked immunosorbent assay (ELISA) was developed for the serodiagnosis of contagious equine metritis (CEM), a sexually transmitted disease caused by Taylorella equigenitalis. Antigen preparation was simple, and antigens derived from both classical and atypical forms of T. equigenitalis enabled detection of antibody responses elicted in horses experimentally exposed to either form of the bacterium. Sera serially obtained from these horses from 0 to 63 days postexposure were tested by the traditional complement fixation test (CFT) for CEM and with the ELISA, using both antigens separately. There was close agreement between CFT and ELISA methodologies during the postexposure time period used to detect CEM serodiagnostically in regulatory animal health testing programs. Unlike the CFT, which requires an overnight incubation step, the ELISAs are more convenient and can be completed in 3 hours.Contagious equine metritis (CEM) is a sexually transmitted infectious infertility of equids caused by the bacterium Taylorella equigenitalis. 6,7 Although endemic in many nations, CEM was eliminated from the US equine population in the early 1980s through stringent preventive regulatory diagnostic testing of both imported and domestic horses prior to use in breeding. 6,7 Stallions may be persistently infected, but they rarely seroconvert; in contrast, mares rapidly but transiently seroconvert following infection and either fail to conceive or abort early. Because T. equigenitalis grows slowly and is difficult to consistently recover from both infected mares and infected stallions, serology in the mare is an essential tool for detecting, controlling, and preventing CEM epizootics in equine breeding populations. 6,7 Traditionally, the complement fixation test (CFT) has been used in the United States for the serodiagnosis of CEM infections. 2,5 The CFT requires, however, an overnight 4 C incubation, will not work reliably with previously frozen serum, and is frequently plagued by anticomplementary or spurious incomplete reactions that are difficult to interpret. 2,5 In the first years after the recognition of CEM as a disease entity, a number of other serological approaches were investigated, including passive hemagglutination, gel immunodiffusion, plate agglutination, and complex early enzymelinked immunosorbent assay (ELISA) methodologies. 5 The simple and convenient ELISA described here can be completed in Ͻ3 hours, works equally well with fresh or previously frozen sera, and yields a well-defined differentiation between positive and negative serum samples.Antigens for the ELISA were prepared from separate 6-day-old Eugon a broth cultures of both classical T. equigenitalis and a recently discovered bacterium that very closely resembles T. equigenitalis but is still of uncertain taxonomic classification. 3 Bacteria centrifuged from both cultures were From the Diagnostic Bacteriology Laboratory, National Veterinary Services Laboratories, Veterinary Services, Animal and Plant Health Inspection Service, US Depart...
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