Serum samples that were positive by ELISA were also screened by hemagglutination-inhibition assay as described (9) . Based on the year and location of NHP sample collection, the estimated ages of the NHPs at the time of sample collection, and the presence of avian H5 and H9 infl uenza viruses in many of these countries during the sampling period (11) (12) (13) , a panel of human vaccine strains and avian infl uenza virus strains was used in the hemagglutination-inhibition assay. Although not all ELISA-positive serum samples could be subtyped, antibodies against seasonal subtype H1N1 and H3N2 infl uenza A strains were detected from macaques in Bangladesh, Singapore, Java, and Sulawesi (Table 2) . Of the performing macaques in Bangladesh, 2 had antibodies against A/chicken/Bangladesh/5473/2010, a strain of G1 clade subtype H9N2 avian infl uenza virus. Subtype H9N2 infl uenza viruses are prevalent in poultry in Bangladesh (14) and have been detected in humans (12) . We did not detect antibodies against highly pathogenic avian infl uenza subtype H5 viruses, which might not be surprising given our relatively small sample size (Table 2) . Also given the small sample size, we were unable to perform microneutralization studies, which would be useful to perform with future samples.