Sero-epidemiology and Molecular Detection of Bluetongue Virus in Goats in Bangladesh

Bluetongue (BT) is an arthropod-transmitted viral non-contagious and infectious disease of domestic ruminants caused by bluetongue virus (BTV). The incidence of BT in Bangladesh is poorly understood, and there is no molecular evidence of BTV in Bangladesh. Thus, the current study has been designed to estimate the seroprevalence of BTV and associated risk factors and identification of BTV molecularly in Bangladesh. Total 460 goat serum samples were randomly collected from ten goat-rich districts of Bangladesh from July 2023 to June 2024. To determine risk factors, farmers were interviewed with a structured questionnaire. Competitive enzyme-linked immunosorbent assay (cELISA) was utilized for screening serum for anti-BTV antibodies. The logistic regression models were applied to identify potential risk factors. ELISA-positive pooled blood samples were considered for RNA extraction and nested RT-PCR was performed for the molecular detection of BTV by using both VP7 and NS1 gene-specific primers. The overall seroprevalence was 63.04% (95%CI:58.63-67.45). Multivariate logistic regression analysis showed that breed (crossbred; OR:3.4, 95%CI:1.34-8.63), sex (female; OR:1.97, 95% CI:1.15-3.40), age (over 2yrs; OR:6.32, 95%CI:2.42-16.81), biosecurity (poor; OR:26.48, 95%CI:1.72-405.6), farm type (household; OR:33.72, 95%CI:3.02-375.5), flock size (large; OR:30.53, 95% CI:2.91-319.6), and vector control (No; OR:27.56, 95%CI:8.60-88.28) were the major risk factors associated with the occurrence of the BTV infection. The VP7 and NS1 genes were amplified at 770 bp and 101 bp by nested‑PCR for molecular confirmation. In conclusion, the study confirmed both the serological evidence and molecular existence of BTV with potential risk factors for occurring BT in goats of Bangladesh.