section_path: Impact of pig husbandry/On public health
section_name: On public health
paragraph_text: On public health
  
  Pig farms can serve as reservoirs of viral diseases that are dangerous to humans and so contribute to their outbreaks in human populations. The 2009 swine flu pandemic was caused by an influenza A variant which had first emerged in pigs. Pigs were also essential to the first outbreak of the Nipah virus in 1999, with 93% of the infected humans having had contact with pigs. While Japanese encephalitis is primarily spread by mosquitoes, pigs are a known intermediary host. There is also a potential for porcine coronaviruses such as porcine epidemic diarrhea virus or swine acute diarrhea syndrome coronavirus to spill over into human populations.