Sero-epidemiology of brucellosis among high risk occupational groups by conventional methods and indirect enzyme linked immunosorbent assay

Brucellosis is a re-emerging bacterial zoonoses and a major health concern worldwide; most cases being undiagnosed or misdiagnosed as pyrexia of unknown origin. The occupational source of exposure predisposes the farmers, shepherds, butchers, laboratory workers, veterinarians and slaughterhouse workers to a greater risk of contracting the disease. The present work was thus undertaken to study the risk of exposure to the high risk occupational groups from different parts of Kerala, and also to compare between conventional test like Rose Bengal Plate test (RBPT) and Standard tube agglutination Test (STAT) with Indirect Immuno-sorbent assay (I-ELISA) for the serodiagnosis of human Brucellosis. A total of 240 human serum samples collected from 83 veterinary doctors, 47 livestock inspectors and 110 slaughter house workers were subjected to RBPT, STAT and Indirect Enzyme-Linked Immuno Sorbant Assay. Out of the 240 samples tested, 56 (23.3%), 2(0.83%) and 13 (5.41%) samples were found positive for antibodies to Brucella abortus by RBPT, STAT and I-ELISA respectively. Among Veterinary Doctors (n=83), RBPT tested positive in 17(20.48%) samples while I-ELISA tested positive in 6(7.22%), but STAT did not give any seropositivity. Among livestock inspectors, (n=47) RBPT tested positive in 8(17%). Among Slaughterhouse workers (n=110), RBPT tested positive in 31 (21.18%) while STAT tested positive in 2 (1.81%) and I-ELISA in 7 (6.36%). Seroprevalence was high in veterinary doctors (7.22%) followed by slaughter house workers (6.36%), and the incidence is high among male population and the highest age group of the affected was of 30-40 years (2.37%). The data collected from the study participants revealed that all the identified positive cases were chronic non vegetarians using all kinds of meat products. The positive cases had not underwent any kind of treatments or never attempted any specific diagnosis for brucellosis ever before. The present study suggests that brucellosis is a professional hazard in the veterinary practitioners and slaughterhouse workers. So periodic screening especially among occupationally exposed people must be done. The disease is easily misdiagnosed because of the deceptive nature of the clinical signs and symptoms. The clinicians may miss many cases of Brucellosis because it is not considered a common disease. Elimination of the infection in animals by vaccination to produce Brucella free animals and products will help to prevent transmission of infection.