How Does a Person Catch Swine Flu?

Swine flu is a respiratory illness caused by influenza viruses that infect the respiratory tract of pigs; these viruses can occasionally infect humans. The disease first came to attention in 1976 with an army recruit's death from swine flu. Widespread fear then led to an often-criticized mass-inoculation program in the United States that resulted in illnesses and deaths.

In spring 2009, numerous cases of swine flu affecting humans were reported, first in San Diego, Calif. Investigators decided the 2009 swine flu strain, first seen in Mexico, should be termed novel H1N1 flu since it was mainly found infecting people and is a mixture of flu viruses from human flu strains, avian (bird) strains, and swine strains.

Small outbreaks have occurred since the pandemic. The latest swine flu virus that has caused swine flu is influenza A H3N2v (commonly termed H3N2v) that began as an outbreak in 2011. The "v" in the name means the virus is a variant that normally infects only pigs but has begun to infect humans. There have been small outbreaks of H1N1 since the pandemic.

Swine flu is transmitted from person to person in the same way other influenza viruses are passed by:

• inhalation or ingestion of droplets containing virus from people sneezing or coughing;
• shaking hands with infected people and then touching your nose, mouth or eyes; or
• touching surfaces contaminated by an infected person coughing or sneezing on them.

H1N1 is not transmitted by eating cooked pork products.

Symptoms of swine flu are similar to those caused by other influenza viruses. These include fever and chills, coughing, sore throat, and fatigue. Sometimes nausea, vomiting, and diarrhea can occur. In the past, pneumonia and potentially fatal respiratory failure have been associated with human swine flu infections. It is not possible to distinguish swine flu from "regular" influenza on the basis of symptoms alone. The symptoms of swine flu can also vary in severity among affected individuals.

Treatment for swine flu involves the use of antiviral medications begun as soon as possible after the onset of symptoms. While the H1N1 virus was incorporated into seasonal flu vaccines, there are no human vaccines available against pure swine flu viruses.

If someone has flu-like symptoms and lives in an area in which swine flu has been documented or suspected, contact a healthcare professional. He or she will be able to advise you as to whether specialized testing for swine flu is advisable. If someone develops severe symptoms such as difficulty breathing, high fever, confusion or dizziness, severe vomiting, worsening of previous flu symptoms, or chest or abdominal pain, it's important to seek emergency medical care right away.

Learn about H1N1 swine flu:

• Swine Flu Collection of Articles
• Swine Flu Symptoms
• Swine Flu FAQ
• Cold and Flu
• Complete Swine Flu Coverage on WebMD