title: Human infection with new influenza A (H1N1) virus: Mexico, update, March-May 2009.
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D055815:Young Adult