Evaluation of an In-house Indirect ELISA for Differential Detection of IgM and IgG anti-Brucella Antibodies in Human Brucellosis

Brucellosis caused by various species of the genus Brucella is one of the most important zoonotic diseases of global importance with veterinary, public health, and economic concerns. The study aimed to standardize IgM and IgG-based iELISA to detect anti-Brucella antibodies for serodiagnosis of acute and chronic human brucellosis. The test was standardized using 1:320 dilution of smooth lipopolysaccharide (sLPS) antigen from B. abortus S99 strain, 1:80 serum dilution, 1:4000 anti-human IgM and IgG conjugates, respectively for both IgM and IgG iELISA. The cut-off using 50 each brucellosis positive and negative human sera panel samples was set at ≥ 42 for both IgM and IgG iELISA. A total of 700 human sera samples were evaluated (137 veterinary doctors, 157 artificial inseminators, and 406 veterinary assistants). Overall, the study detected 8.3%, 8.1%, 8%, and 6.1% positivity by in-house IgG iELISA, RBPT, IgM iELISA, and SAT tests, respectively. Considering commercial iELISA kit as a gold standard, the sensitivities of IgM and IgG iELISA were 90% and 97.9%, respectively, whereas, specificities were >99%. The study established >98% specificity and >90% sensitivity for differential detection of immunoglobulin classes in the standardized iELISA. The developed assay outperformed the other evaluated tests with a shorter assay time and can be implemented in both endemic and non-endemic regions for surveillance and diagnosis of human brucellosis

Management of bovine brucellosis in organized dairy herds through the identification of risk factors: A cross-sectional study from Karnataka, India

Background and Aim: Brucellosis is an infectious disease caused by Brucella species. This study aimed to identify the risk factors associated with bovine brucellosis seropositivity in organized dairy farms to control the disease in unvaccinated adult bovine herds in Karnataka, India. Materials and Methods: In total, 3610 samples (3221 cattle and 389 buffaloes) were subjected to parallel testing using the Rose Bengal plate test and protein G-based enzyme-linked immunosorbent assay, followed by analyses of animal- and farm-level epidemiological datasets to identify the risk factors. Results: The apparent brucellosis prevalence at the animal level was higher in buffaloes (8.2%, 95% confidence interval [CI] = 5.9–11.4) than in cattle (6.1%, 95% CI = 5.3–7.0). In a multivariable logistic model, animals calved 3–5 times (odds ratio [OR] = 2.22, 95% CI = 1.50–3.1, reference [ref]: animals calved <2 times); animals with a history of abortion (OR = 54.73, 95% CI = 33.66–89.02), repeat breeding (OR = 19.46, 95% CI = 11.72–32.25), and placental retention (OR = 13.94, 95% CI = 4.92–39.42, ref: no clinical signs); and dogs on farms (OR = 2.55, 95% CI = 1.48–4.40, ref: absence of dogs); disposal of aborted fetus in open fields (OR = 4.97, 95% CI = 1.93–12.84) and water bodies (OR = 2.22, 95% CI = 1.50–3.1, ref: buried); purchase of animals from other farms (OR = 6.46, 95% CI = 1.01–41.67, ref: government farms); hand milking (OR = 1.98, 95% CI = 1.02–10.0, ref: machine milking); and use of monthly veterinary services (OR = 3.45, 95% CI = 1.28–9.29, ref: weekly services) were considered significant risk factors for brucellosis in organized bovine herds (p < 0.01). Conclusion: The study identified that the animals calved 3–5 times or with a history of abortion/repeat breeding/placental retention, and disposal of aborted fetus in open fields/water bodies as the potential risk factors for bovine brucellosis. These risk factors should be controlled through the implementation of best practices to reduce the brucellosis burden in bovine farms