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Case Description: A 7-year-old Quarter Horse gelding used for unsanctioned racing was examined because of fever and anorexia., Clinical Findings: Physical examination revealed fever, tachycardia, and tachypnea. Results of a CBC indicated anemia and mild thrombocytopenia. Results of microscopic examination of a blood smear indicated piroplasms in erythrocytes, consistent with Babesia spp. Regulatory authorities were contacted, and results of serologic testing at the National Veterinary Services Laboratories confirmed acute Babesia equi infection., Treatment and Outcome: Equids on the home premises of the index horse were placed under quarantine. Those equids were tested for piroplasmosis, and 6 of 63 horses had positive results for B equi. Another horse that had previously been housed on the index premises also had positive results for B equi. Competent tick vectors for piroplasmosis organisms were not identified. All 8 horses with piroplasmosis were Quarter Horses that participated in unsanctioned racing and were trained by the same person. Two of the horses were illegally removed from the index premises; these 2 horses and the other horse with piroplasmosis that was previously housed on the index premises could not be found. The other 5 horses with piroplasmosis were euthanized. Investigators concluded that transmission of B equi among horses was most likely iatrogenic., Clinical Relevance: The United States has been considered piroplasmosis free. However, veterinarians should consider piroplasmosis in horses with signalments and clinical signs similar to those of the index horse of this report. Regulatory authorities should be contacted regarding horses in which piroplasmosis is suspected.

Case Description: A 7-year-old Quarter Horse gelding was hospitalized in Ocala, Fla, because of lethargy, fever, anorexia, and swelling of distal aspects of the limbs. A tentative diagnosis of equine piroplasmosis (EP) was made on the basis of examination of a blood smear. The case was reported to the Florida State Veterinarian, and infection with Babesia equi was confirmed. The subsequent investigation included quarantine and testing of potentially exposed horses for B equi and Babesia caballi infections, tick surveillance, and owner-agent interviews., Clinical Findings: 210 horses on 25 premises were tested for infection with EP pathogens. Twenty B equi-infected horses on 7 premises were identified; no horses tested positive for B caballi. Seven horses, including the index case, had clinical findings consistent with EP Dermacentor variabilis was considered the only potential tick vector for B equi collected, and all D variabilis specimens tested negative for Babesia organisms via PCR assay. Results of the epidemiological investigation suggested that B equi was spread by use of shared needles and possibly blood transfusions. All horses that tested positive were involved in nonsanctioned Quarter Horse racing, and management practices were thought to pose substantial risk of transmission of blood-borne pathogens., Treatment and Outcome: Final outcome of B equi-infected horses was euthanasia, death from undetermined causes, or shipment to a US federal research facility., Clinical Relevance: This investigation highlights the importance of collaboration between private veterinary practitioners, state veterinary diagnostic laboratories, and regulatory officials in the recognition, containment, and eradication of foreign animal disease.

Objective: To estimate the prevalence of Mycobacterium avium subsp paratuberculosis infection among cows on beef operations in the United States., Design: Cross-sectional seroprevalence study. Sample Population-A convenience sample of 380 herds in 21 states., Procedures: Serum samples were obtained from 10,371 cows and tested for antibodies to M avium subsp paratuberculosis with a commercial ELISA. Producers were interviewed to collect data on herd management practices., Results: 30 (7.9%) herds had 1 or more animals for which results of the ELISA were positive; 40 (0.4%) of the individual cow samples yielded positive results. None of the herd management practices studied were found to be associated with whether any animals in the herd would be positive for antibodies to M avium subsp paratuberculosis., Conclusions and Clinical Relevance: Results suggest that the prevalence of antibodies to M avium subsp paratuberculosis among beef cows in the United States is low. Herds with seropositive animals were widely distributed geographically.

Forty-eight cattle were used in 4 experiments; 6-week-old calves in experiments 1-3 (n = 24) and 10-month-old heifers in experiment 4 (n = 24). In experiments 1-3, 7 groups of 3 calves each were inoculated SC with 5 strains of Brucella abortus: virulent strain 2308 (2 groups), vaccine strain 19 (2 groups), and mutant strains RB51. 19 delta 31K, and 19 delta SOD. Sera and lymph node tissues were examined at 2-week intervals for evidence of infection. At postinoculation (PI) week 12, 2 calves in each group were given dexamethasone for 5 days. Calves were then euthanatized and lymphoid tissue, spleen, liver, and bone marrow were examined for evidence of B abortus. Calves given strain 2308 had large numbers of bacteria in their lymph nodes, marked granulomatous lymphadenitis in the deep cortex, and loss of lymphoid cells in superficial cortical areas. In addition, they had high serum antibody titers at PI week 16. Calves given strain 19, or genetic mutants derived from strain 19, cleared bacteria from lymph nodes more rapidly, had less lymphoid destruction, and developed antibody titers that did not persist for 16 weeks. The RB51 strain (rough) was cleared most rapidly from lymphoid tissues and induced serum antibody responses only to the core of the lipopolysaccharide molecule. Treatment of calves with dexamethasone did not cause B abortus to reappear in tissues of any calves, nor did serum antibody titers increase.(ABSTRACT TRUNCATED AT 250 WORDS)

A microagglutination test was used to identify Brucella dominant antigens from 400 Brucella and non-Brucella cultures. There was 100% agreement between microagglutination and tube agglutination tests in identifying dominant antigen.