Abstract
We evaluated West Nile virus (WNV) antibody persistence by using follow-up plasma samples from 35 blood donors who made viremic donations in 2005. At 26 to 34 days of follow-up, all of the donors (n = 33) were positive for WNV immunoglobulin M (IgM), IgA, and IgG. At 1-year of follow-up, 17% of the donors (n = 23) were positive for WNV IgM, 57% were positive for WNV IgA, and 100% were positive for WNV IgG.