title: Influenza--the world problem.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000956:Antigens, Viral; D004196:Disease Outbreaks; D014644:Genetic Variation; D005827:Genetics, Microbial; D006389:Hemagglutinins, Viral; D006801:Humans; D007109:Immunity; D007125:Immunogenetics; D007251:Influenza, Human / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology* / Q000401:mortality; D008875:Middle Aged; D009439:Neuraminidase; D009975:Orthomyxoviridae / Q000201:enzymology / Q000276:immunology* / Q000302:isolation & purification; D012621:Seasons; D014944:World Health Organization
chemical_list: D000956:Antigens, Viral; D006389:Hemagglutinins, Viral; D009439:Neuraminidase