Prevalence and risk factors associated with Japanese encephalitis virus infection in swine population of Assam, India

Abstract

Objective: To assess the prevalence of Japanese encephalitis virus (JEV) and associated risk factors in the swine population of Assam. Methods: A total of 432 swine serum and blood samples were collected from Barpeta and Sonitpur districts of Assam and were screened for the presence of JEV antibodies. Information related to risk factors was collected using a self-designed questionnaire from 120 swine-rearing farmers. Linear-mixed models were used for prevalence estimation. Univariate and multivariate regression models were constructed to evaluate the association of demography, season and management practices with JEV positive status. Results: Overall, the JEV infection prevalence was 51.6% at farm and 47.1% at slaughter premises. Phylogenetic analysis of partial sequence of envelope gene of two positive field samples revealed that both isolates belonged to genotype III JEV. Isolate 1 shared a common clade with human isolates while isolate 2 belonged to the same clade as that of other JEV swine strain isolated from India. The final multivariate model showed that two factors including monsoon season (Adjusted OR 5.6; 95% CI 2.1-14.9; P<0.001) and water logging in the area near the pig shelter (Adjusted OR 16.9; 95% CI 6.1-47.3; P<0.001) were associated with greater odds of swine being infected with JEV. Conclusions: High prevalence of JEV in swine population of Assam state indicates a significant risk of virus transmission to humans while risk factor study underlines the urgent need for awareness campaigns in the Assam.

Keywords

• japanese encephalitis virus; genotypes; prevalence; risk factors; swine