Swine influenza, also known as H1N1 flu, is caused by viruses commonly found in pigs. The virus can spread easily from human to human, causing global outbreaks. Symptoms are similar to regular human influenza and include fever, cough, sore throat, and body aches. At-risk groups like children, diabetics and heart patients should take extra precautions by avoiding crowds and seeking medical care quickly if symptoms worsen.