section_path: In animals/Pigs
section_name: Pigs
paragraph_text: Pigs
  
  Influenza in pigs is a respiratory disease similar to influenza in humans and is found worldwide. Asymptomatic infections are common. Symptoms typically appear 1–3 days after infection and include fever, lethargy, anorexia, weight loss, labored breathing, coughing, sneezing, and nasal discharge. In sows, pregnancy may be aborted. Complications include secondary infections and potentially fatal bronchopneumonia. Pigs become contagious within a day of infection and typically spread the virus for 7–10 days, which can spread rapidly within a herd. Pigs usually recover within 3–7 days after symptoms appear. Prevention and control measures include inactivated vaccines and culling infected herds. Influenza A virus subtypes H1N1, H1N2, and H3N2 are usually responsible for swine flu.
  
  Some influenza A viruses can be transmitted via aerosols from pigs to humans and vice versa. Pigs, along with bats and quails, are recognized as a mixing vessel of influenza viruses because they have both α-2,3 and α-2,6 sialic acid receptors in their respiratory tract. Because of that, both avian and mammalian influenza viruses can infect pigs. If co-infection occurs, reassortment is possible. A notable example of this was the reassortment of a swine, avian, and human influenza virus that caused the 2009 flu pandemic. Spillover events from humans to pigs appear to be more common than from pigs to humans.