Seroepidemiological Investigation and Risk Factors of Schmallenberg Virus Infection in Sheep and Goats in Bangladesh

Schmallenberg virus (SBV) is an emerging vector-borne pathogen that significantly impacts the health and productivity of both domesticated and wild ruminants, leading to considerable economic losses. Its transmission via arthropod vectors raises concerns about potential geographic expansion, particularly to South Asia, including Bangladesh, where livestock farming plays a vital role in rural livelihoods. Hence, this study aimed to estimate the serological evidence of SBV exposure and identify associated risk factors in small ruminants in Bangladesh from January 2017 to June 2019. Individual animal characteristics were recorded using a structured questionnaire. A total of 517 serum samples were collected from randomly selected goats (n = 230) and sheep (n = 287) across three districts: Dhaka, Chattogram, and Faridpur, representing both market and household settings. Serum samples were screened using a commercial indirect multi-species ELISA to detect antibodies against the SBV nucleoprotein. The overall seroprevalence of SBV was 19.5% (101/517, 95% CI: 16.2-23.2), with sheep showing higher seropositivity at 30.0% (86/287, 95% CI: 24.7-35.6) compared to goats at 6.5% (15/230, 95% confidence interval [CI]: 3.7-10.5). In a multivariable logistic regression model, sheep had significantly higher odds of SBV seropositivity than goats (odds ratio [OR]: 6.4; 95% CI: 3.6-12.2; p  < 0.01). Animals drinking from pond water sources also had a greater risk than those using supplied water (OR: 2.3; 95% CI: 1.2-4.5; p = 0.01). This study provides the first serological evidence of SBV exposure in small ruminants in Bangladesh. The findings underscore the need for targeted surveillance and improved biosecurity and management practices to reduce the risk of SBV transmission in the region.