The epidemiology of West Nile virus (WNV) in Ghana, sub-Saharan Africa, and its relevance to transfusion were newly assessed. A total of 1324 plasma samples from five Ghanaian populations, including 529 children (<6 y old, pre-transfusion) and 795 adults (236 blood donors, 226 HIV-infected or non-infected pregnant women, 203 HIV symptomatic patients, and 130 AIDS patients) were screened for WNV RNA. No WNV RNA was detected, but 4.8% (13/271) and 27.9% (127/455) carried specific IgG in children and adults, respectively, and 2.4% (4/167) of the children had IgM. The prevalence of IgG antibody to WNV increased progressively and peaked around 30% between ages 1 and 30 y, then stabilized. The absence of viremia in four WNV IgM-positive children, and of reactivation in HIV-infected patients suggests that once host immunity is established, it appears to be robust. In addition, there were no clinical reports of WNV infection in the hospital in Kumasi, Ghana, suggesting that WNV epidemiology in Ghana differs from that seen in the U.S. Most infections occur early in life, and as the window for infection is quite short, the risk of transmission by transfusion appears to be low, and the risk of pathogenicity in immunocompetent recipients appears to be limited in an endemic area such as Ghana.