BACKGROUND: Brucellosis is one of the most common zoonosis in Middle East and Iran. OBJECTIVES: The purpose of this study was genomic detection of Brucella spp. in sero-positive dairy cattle. METHODS: We have collected 28,519 blood samples from cows during 2012-2013. Samples were screened by Slide and tube agglutination and 2-Mercaptoethanol tests. Samples with anti-Brucella antibodies titer ≥ 1:80 and ≥1:40 in tube agglutination and 2-ME tests were considered as positive respectively. Tissue samples include: lymph nodes, liver, testicle and kidney from 122 samples of slaughtered cows were collected. The Sero-positive samples were examined by a collection of specific primers for Brucella abortus, Brucella melitensis, vaccinal strains included RB51 and Rev1 using PCR tests. RESULTS: Results showed that 450 samples were positive in slide agglutination test and 447 samples had anti-brucella antibodies titer equal to or more than 1:80. So they were positive by tube agglutination test. Three hundred eighty nine samples were positive by 2- mercaptoethanol test. PCR test results showed that 46 samples (37.7%) out of 122 samples had a specific sequence of Brucella or otherwise they have an active infection with Brucella species, whereas 62.3% of samples were negative. The PCR results showed that 2 samples (4.35%) were infected by B. melitensis, 2 samples (4.35%) infected by Rev1 strain and 42 samples (91.3%) were infected by B. abortus. CONCLUSIONS: The results showed that, as we had expected, the majority of cows were infected by B. abortus. Animals who infected by B. melitensis and Rev1 strain may be a result of contact with sheep or goats. We couldn’t find Brucella genome in 76 samples (62.3%) of sero-positive cows. It may be caused by cross reaction of sera with Brucella species in tests or activation of immune system response and elimination of organism from internal organs.

Twenty-four rams inoculated with Brucella ovis by conjunctival and preputial routes were treated with a long-acting oxytetracycline alone or in combination with dihydrostreptomycin sulfate. The combined treatment eliminated Brucella ovis from 11 of 12 (91.6%) treated rams. Only 4 of 12 (33.3%) rams treated with oxytetracycline alone were bacteriologically negative. Neither treatment resolved clinical epididymitis in 2 rams affected before treatment. Many rams had pathologic lesions in the epididymis and ampullae, which limited the efficacy of antibiotic treatment.

Brucellosis is an endemic disease in Zimbabwe caused by the genus <em>Brucella</em>. <em>Brucella</em> seroprevalence was recently reported to be high in the wildlife-livestock interface in the Chiredzi district and the neighbouring Gonarezhou National Park (GNP) in Zimbabwe, and higher amongst communal cattle with an abortion history and access to grazing in GNP than amongst communal cattle with no abortion history or access to grazing in GNP. The aim of this study was to investigate <em>Brucella</em> species in brucellosis seropositive cattle in the Chiredzi district with access to GNP using isolation and identification. Isolation of<em> Brucella </em>species from whole blood (<em>n</em> = 18) and milk samples (<em>n</em> = 10) from seropositive animals with an abortion history was based on the rose Bengal test (RBT) and enzyme-linked immunoassays (enzyme- linked immunosorbent assay [ELISA]; indirect ELISA and complement ELISA), using microbiology and polymerase chain reaction (PCR) methods. <em>Brucella abortus</em> was cultured and identified from blood and milk collected from seropositive cows in both communal areas. The<em> Brucella</em>-specific 16-23S intergenic spacer (ITS) PCR and multiplex AMOS-PCR assays verified the identification of the cultures. Our results confirmed that <em>B. abortus</em> is present in cattle on communal farms in the Chiredzi district in Zimbabwe and might cause cattle abortions. The need for implementing control measures and raising public awareness on zoonotic transmission of brucellosis are recommended.

Objective-To estimate receiver-operating characteristic (ROC) curves for a competitive ELISA (c-ELISA) that is used in serodiagnosis of brucellosis in water buffalo and cattle, to determine the most appropriate positive cutoff value for the c-ELISA in confirmation of infection, and to evaluate species differences in c-ELISA function. Sample population-Sera from 4 herds of cattle (n = 391) and 4 herds of water buffalo (381). Procedure-Serum samples were evaluated for Brucella-specific antibodies by use of a c-ELISA. On the basis of previous serologic test results, iterative simulation modeling was used to classify animals as positive or negative for Brucella infection without the use of a gold standard. Accuracy of c-ELISA for diagnosis of infection was compared between cattle and water buffalo by comparison of areas under ROC curves. Results-A positive cutoff value of 30% inhibition for c-ELISA yielded sensitivity and specificity estimates, respectively, of 83.9 and 92.6% for cattle and 91.4 and 95.4% for water buffalo. A positive cutoff value of 35% inhibition yielded sensitivity and specificity estimates, respectively, of 83.9 and 96.2% for cattle and 88.0 and 97.4% for water buffalo. Areas under ROC curves were 0.94 and 0.98 for cattle and water buffalo, respectively. Conclusion and Clinical Relevance-ROC curves can be estimated by use of iterative simulation methods to determine optimal cutoff values for diagnostic tests with quantitative outcomes. A cutoff value of 35% inhibition for the c-ELISA was found to be most appropriate for confirmation of Brucella infection in cattle and water buffalo.

Objective-To estimate sensitivity and specificity of 4 commonly used brucellosis screening tests in cattle and domestic water buffalo of Trinidad, and to compare test parameter estimates between cattle and water buffalo. Animals-391 cattle and 381 water buffalo. Procedure-4 Brucella-infected herds (2 cattle and 2 water buffalo) and 4 herds (2 of each species) considered to be brucellosis-free were selected. A minimum of 100 animals, or all animals > 1 year of age, were tested from each herd. Serum samples were evaluated for Brucella-specific antibodies by use of standard plate agglutination test (SPAT), card test (CT), buffered plate agglutination test (BPAT), and standard tube agglutination test (STAT). A Bayesian approach was used to estimate sensitivity and specificity of diagnostic tests without the use of a gold standard, assuming conditional independence of tests. Results-Sensitivity and specificity estimates in cattle, respectively, were SPAT, 66.7 and 98.9; CT, 72.7 and 99.6; BPAT, 88.1 and 98.1; and STAT, 80.2 and 99.3. Corresponding test estimates in water buffalo, respectively, were SPAT, 51.4 and 99.3; CT, 90.4 and 99.4; BPAT, 96.3 and 90.7; and STAT, 75.0 and 98.8. Sensitivity of the CT and specificity of the BPAT were different between cattle and water buffalo with at least 95% probability. Conclusions and Clinical Relevance-Brucellosis serologic test performance varied by species tested, but BPAT had the highest sensitivity for screening cattle and water buffalo. Sensitivity and specificity of more than 2 screening tests can be estimated simultaneously without a gold standard by use of Bayesian techniques.

Results of a double agar gel immunodiffusion (Ouchterlony) test that contained a polysaccharide (poly-B) antigen of Brucella melitensis strain B115 were compared with those of 5 other serotests. To determine the sensitivity and specificity of the immunodiffusion, standard tube, 2-mercaptoethanol, Rivanol, card, and complement fixation tests, sera obtained from 1,328 vaccinated, infected and seronegative cattle, 56 of which had been examined bacteriologically, were used to evaluate the humoral response to Brucella sp. The poly-B antigen confirmed infection in 87.5% of the 56 cattle from which Brucella abortus biotype 1 had been isolated, and in 96.6% (205/212) of a group of cattle suspected to be infected on the basis of results of conventional serotests. Likewise, sera from 4 groups of vaccinated cattle did not react with poly-B antigen, whereas they did not react in conventional tests. The poly-B antigen was more specific in detecting infected cattle even in a group of vaccinated adults. A useful strategy to identify infected cattle might be screening, using a combination of the Rivanol and card tests together with the agar-gel immunodiffusion test containing poly-B antigen.

No abstract available.