Animal farm: pig in the middle.
D000818:Animals; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000502:physiology; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D038622:Internationality; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D011159:Population Surveillance; D013552:Swine / Q000821:virology; D013553:Swine Diseases / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D015047:Zoonoses / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology