Swine flu, also known as swine influenza, is a type of influenza virus that can infect humans and is believed to have originated in pigs. Although typically a disease of pigs, occasional outbreaks of swine flu occur worldwide. The H1N1 strain is responsible for swine flu in humans.
Symptoms of swine flu closely resemble those of seasonal flu, including fever (typically over 38°C), muscle aches, sore throat, and a dry cough. Most cases resolve within a week without specific treatment. The exact incubation period is uncertain but is thought to range from two to seven days. Infected individuals are most contagious shortly after symptom onset, remaining so for up to five days (seven in children). Infectivity decreases as symptoms improve, and individuals are typically no longer contagious once symptoms subside.