Reports suggest that these patients are infected the Influenza A(H1N1) virus. However, there is a problem: the majority of the cases are not in the typical risk groups. They are adults between the ages of 20 to 60 with no other underlying health concerns.
|[Influenza A(N1H1) evolution]|
The Influenza A(H1N1) virus is prone to mutations and has already changed several times since its first appearance in 2009. Has it mutated again?
 Anderson et al: Population dynamics of cocirculating swine influenza A viruses in the United States from 2009 to 2012 in Influenza and Other Respiratory Illnesses – 2013.