Swine flu, also called H1N1 influenza type A, is a virus that originated in pigs but can infect humans. It spreads through direct or indirect contact with infected pigs or people. Symptoms in humans include fever, headaches, coughing and sore throat. The virus was first detected in Mexico in 2009, where it caused several hundred deaths and economic impacts through reduced tourism. Prevention efforts include the Tamiflu medication and annual flu vaccines.