Molecular Epidemiology of Japanese Encephalitis Virus, Taiwan

Europe (8), resident populations in these countries have been exposed to these virus lineages more frequently than populations in Asia, and therefore may have acquired a greater degree of preexisting cross-reactive immunity to pandemic (H1N1) 2009 virus. A recent review of human swine infl uenza infections suggests that they may not be uncommon (9), although the true incidence of human infections with swine infl uenza is unknown because of paucity of swine infl uenza surveillance data worldwide (8). In conclusion, partial cross-immunity and cell-mediated immunity may be present but not detected by HI or MN assays. Thus, results of standard serologic assays may not be providing all relevant data (10).