Prevalence of West Nile virus among blood donors among South Indian population

Abstract BACKGROUND: West Nile virus (WNV) cases are being increasingly reported from various states in India in the last decade and its one mode of transmission is blood transfusion. AIM: It is crucial to study the serological and molecular prevalence of WNV among South Indian blood donors and this data will help guide policy in blood bank. SUBJECTS AND METHODS: Five hundred consenting South Indian blood donors who were at high risk for WNV infection screened by the blood bank criteria and a specific study questionnaire were recruited for the study during the period 2020–2021. Serum samples from these donors were subjected to both WNV immunoglobulin (Ig) M and IgG testing by indirect enzyme-linked immunosorbent assay (ELISA) (Euroimmun, Germany). Further confirmation of positive samples was done by IgM Capture ELISA (InBios International Inc. USA). A random subset ( n = 100) of negative samples (both IgG and IgM) were subjected to WNV real-time polymerase chain reaction (PCR). RESULTS: The number of samples that were positive for West Nile-specific IgG and IgM antibodies were 72% and 0.20%, respectively, among South Indian blood donors. Viremia was negative in a subset of 100 samples by real-time PCR targeting the NS5 region. Age seroprevalence of WNV is statistically significant, with a P = 0.02. CONCLUSIONS: High seroprevalence (72%) of WNV IgG suggests the circulation of WNV among the South Indian population and past exposure to the virus. Since no viremia was detected and very low seroprevalence of IgM, implementing nucleic acid testing for screening for WNV currently among blood donors in South India may not be necessary.