SERO-PREVALENCE OF BOVINE BRUCELLOSIS IN WEST BENGAL, INDIA: A 15 - YEARS STUDY

Bovine brucellosis is an important zoonotic disease caused by Brucella abortus. The distribution of bovine brucellosis in West Bengal has not been reported so far. Here, a longitudinal epidemiological study was conducted from April 2002 to March 2016 to determine the distribution, pattern and trend of bovine brucellosis in different organized and unorganized farms of West Bengal, India. Bovine serum samples were examined for identification of brucellosis by Rose Bengal Plate Test and indirect ELISA. Results envisaged that the prevalence of brucellosis is 11.12 times higher in organized farm (average 6.6%) compared to rural areas (average 0.6%) with overall prevalence was 3.9%. The highest and lowest level of sero-positivity was observed in 2015 and 2011 with 9.8% and 0.5% respectively. In reference to the year 2002, trend of brucellosis was decreasing up to 2013 in a fluctuating manner (odd ratio ranging from 1.7 to 2.3); however, it again increased in 2014 and 2015 with final decrease in 2016. In organized farms, highest (12.6%) and lowest (0.6%) level of prevalence was recorded in 2015 and 2011 respectively. In rural areas, the highest and lowest level of prevalence was observed in 2010 and 2008 with 1.8% and 0.15% respectively. Chi square statistics revealed that location of cattle (χ2 =713.8, df=1, p<0.001) and year of sample collection (χ2 = 468.6, df=14, p<0.001) contributed significantly to increasing or decreasing sero-positivity. A univariate logistic regression analysis also revealed that location of the animals either in organized farm or in rural areas and year(s) of sampling have statistically significant (p<0.001) effect on individual animal level sero-positivity. The results suggested that brucellosis is endemic and moderately distributed in different regions of West Bengal including Burdwan, Nadia, Paschim Medinipur, Murshidabad and Hoogly districts.