PREVALENCE AND DETERMINANTS OF BRUCELLOSIS IN DAIRY CATTLE OF SYLHET DISTRICT

Abstract

Brucellosis is an infectious, emerging and key zoonotic disease, which has a great impact on the productive, reproductive performance and economic significance. Brucellosis is considered as an endemic disease in different countries of Asia including Bangladesh. The scenario of brucellosis in Sylhet District is totally unknown. Therefore, a cross-sectional followed by case control study was carried out to assess the prevalence of brucellosis and determinants associated with sero-positivity in dairy cattle of Sylhet District. A total of 386 sera and data on biologically plausible risk factors from 63 dairy herds with their spatial locations were collected from urban and peri-urban regions of 12 upazilas (Subdistrict) at Sylhet using multistage random sampling. The sera were tested with Rose Bengal Brucella antigen test (RBT), Brucella abortus Plate Agglutination Test (BPAT) and Serum Agglutination Test (SAT) to find out the sero-positivitity. A sample was considered to be positive if any one of these three tests showed positive reaction. The study revealed an overall 17.09% (95% CI: 13.67%-21.18%) prevalence in cows and 73.02% (95% CI: 60.97%-82.42%) prevalence in farms. Cross and local breed cows showed almost same prevalence with cross bred 17.12% (95% CI: 12.73%-22.62%) and local breed 17.07% (95% CI: 12.08%-23.57%) and there was no differences in prevalence between breeds. Relatively higher prevalence (56.08%; 95% CI: 42.23%-70.32%) was recorded in cows having parity ≥4 than the other cows with parity 0, 1, 2 and 3. High prevalences were observed in upazilas which shared border with India. Among the 12 upazilas, kanaighat exemplified the highest prevalence with 32.35% (95% CI: 19.13%- 49.15%). Prevalence was significantly higher in cows with history of abortion 90.63% (95%CI: 75.79%-96.76%), repeat breeding 79.17% (95% CI: 65.74%-88.27%) and reproductive abnormalities other than abortion and repeat breeding 48.54% (95% CI: 39.12%-58.07%) compared to cows without history of reproductive abnormalities. Farm level prevalence were found to be high in farms with previous history of abortion 95.45% (95% CI: 78.20%-99.19%) and repeat breeding 90.00% (95% CI: 74.38%-96.54%) than farms without that history. From multivariable logistic regression analysis it was estimated that the animals of parity ≥4 were at higher risk (OR=7.82) than the others. History of abortion, repeat breeding and reproductive abnormalities in cow were the determinants significantly associated with Brucella antibody sero-positivity. Among the herd level factors, only history of repeat breeding in herds was found to be positively association with Brucella antibody positivity and OR was 6.25. The prevalence was higher than the other previous studies in different regions in Bangladesh, which might be a concern in public health point of view. Eventually, Public awareness about the bovine brucellosis and national control measures are necessary to minimize the impact of brucellosis.