A Case–control Study on the Role of Deer Fly in the Transmission of Hepatitis B in Kerala, South India

BACKGROUND: The sudden increase in the number of Hepatitis B-positive cases between December 2018 and June 2019, in Pathanamthitta District of Kerala in South India, aroused fear both among the government and the people. Some earlier studies postulated that deer flies act as vectors for the transmission of Hepatitis B. Deer flies were found to be in plenty in the concerned area and their bite was also considered part and parcel of everyday life. Hence, it was considered necessary to prove whether deer flies played a role in the transmission of Hepatitis B. AIMS AND OBJECTIVE: The aim of this study is to investigate the role of deer fly in the transmission of Hepatitis B. MATERIALS AND METHODS: A case–control study design was adopted to test the hypothesis concerning the possible role of deerfly in disease transmission. Cases were those who were picked up by the routine surveillance system (Integrated Disease Surveillance Project) and found to be positive for Hepatitis B surface antigen (HBsAg). Controls were age- (±5 years) and gender-matched neighborhood individuals negative for HBsAg. Data was collected with the help of a pretested interview schedule. RESULTS: There was no significant association between bite of deer flies and acquisition of Hepatitis B. CONCLUSION: This study concluded proving the deer fly hypothesis to be false.