New influenza A(H1N1)   virus infections: global   surveillance summary,   May 2009.
D002170:Canada / Q000453:epidemiology; D004196:Disease Outbreaks; D005060:Europe / Q000453:epidemiology; D014943:Global Health; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission / Q000821:virology; D008800:Mexico / Q000453:epidemiology; D011159:Population Surveillance; D014481:United States / Q000453:epidemiology