A cross-sectional study on swine brucellosis sero-survey in Nagaland state of North Eastern India

Swine brucellosis caused by the bacterium Brucella suis, is an important zoonotic disease characterized by abortion, birth of dead or weak piglets, orchitis in males, lameness and sometimes paralysis. Brucellosis is endemic to many Indian states but disease status is unknown in the pig-rearing state of Nagaland in North-Eastern India. The present study aimed to survey presence of anti-Brucella antibodies in pigs to understand the serological status of disease. A cross-sectional study design was adopted resulting in collection of 1550 serum samples from nine out of eleven districts, 43 out of 74 blocks (58.10% of blocks) and 59 out of 1428 epiunits called villages (4.13% of epiunits) and serum samples were tested by in-house developed indirect ELISA. In the study, more males (n-932) were tested compared to female pigs (n-618) which is approximately in the ratio of 3:2. Overall, 6.84% (5.69-8.2) apparent prevalence for brucellosis (AP) was noted with the highest sero-prevalence of 53.77% in Wokha district followed by Zunhebot, Tuensang and Kiphire districts as 6.82, 5.22 and 4.14%, respectively and least sero-positivity (2%) in Dimapur (the largest district) and Kohima district (the capital of Nagaland). At epiunit level, 100% sero-prevalence was recorded in two epiunits, >15% in three epiunits and >10% prevalence in four epiunits. Non-significantly higher sero-prevalence was recorded in males (7.40%) alongwith significantly higher prevalence in 24-month-old pigs (17.85%). The study identified swine brucellosis endemic regions in the state of Nagaland, which will be helpful for planners in implementing intervention measures in the absence of a vaccination policy for pigs in the country.