We examined 48 published studies for which sample sizes could be ascertained to determine the historic prevalence of influenza A(H7N9) virus in wild bird populations and reviewed GenBank data to further establish its distribution. Low prevalence (0.0093%) in Asia suggests > 30,000 samples would be required to detect the H7N9 subtype in wild birds.
Keywords: expedited, population surveillance; influenza, influenza A virus, H7N9 subtype, wild animals, wild birds, avian, Asia, viruses, zoonoses, viruses.