Swine flu is caused when the Influenza virus infects a person's nose, throat, and lungs. The virus is transmitted to various hosts through inhaling contaminated droplets in the air, or when a person touches a mucosal portion of their body (eyes, nose, mouth) with their hand after it has touched a contaminated area.
The flu virus is possibly one of the most evolutionarily inclined viruses today, and the H1N1 virus is just the most recent revolution in the development of this virus. The reason why this strain of the flu is called the "swine flu" is because many of the genes found in the virus are closely related to those in flu viruses found in pigs. Unlike the flu virus found in pigs, though, the H1N1 virus not only has two genes which are normally found in pigs in Europe and Asia as well as bird genes and human genes. Because there are four primary flu genes which make up this particular strain, scientists who are researching it call it a "quadruple reassortant" virus.
Period of Contagion
In adults, a person is able to spread H1N1 24 hours before they begin to show symptoms and up to a week after they contract the virus. In order to avoid contracting the virus unnecessarily, practice proper hygiene and maintain distance from those who are or who seem infected with the virus. Also, get vaccinated with either the flu shot or with the nasal spray vaccine.
If a person is experiencing vomiting, diarrhea, fever, coughing, a sore throat, body aches, a stuffy or runny nose, chills, or fatigue, then they should seek medical attention, as they may be infected with H1N1.