Update on human cases of highly pathogenic avian influenza A(H5N1) virus infection, 2011

This report describes the epidemiology of the 62 laboratory confirmed human infections with highly pathogenic avian influenza A(H5N1) virus that were reported to WHO from 5 countries during 2011. Of these reported cases, 51 occurred as sporadic cases, with 12 (including 1 in early 2012) occurring in 5 clusters in 3 countries.