What is swine flu, and how is swine flu different from other kinds of flu? How does a person catch swine flu?

Swine flu is a respiratory illness of pigs caused by infection with swine influenza A virus (SIV) that can occasionally affect humans. The disease first came to attention in 1976 with the death of an army recruit from swine flu. Widespread fear then led to an often-criticized mass inoculation program in the United States that resulted in illnesses and deaths.

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. There is no human vaccine to protect against swine flu, although vaccines are available to be given to pigs to prevent swine flu.

In spring 2009, numerous cases of swine flu affecting humans were reported, first in San Diego, California. From 2005 up to this outbreak, only 12 cases of human swine flu were reported in the U.S., none of which resulted in death. Although many cases of swine influenza A virus infection occur in individuals who have had recent direct contact with pigs or close (within 6 feet) contact with pigs, human-to-human transmission has been documented for the 2009 swine flu outbreak. It is believed that this swine flu virus spreads through airborne particles containing the virus that are released when an infected person coughs or sneezes. It is not possible to get swine flu from eating pork.

When to seek medical care

If you have flu-like symptoms and live in an area in which swine flu has been documented or suspected, contact your health-care practitioner. He or she will be able to advise you as to whether specialized testing for swine flu is advisable. If you develop severe symptoms such as difficulty breathing, high fever, confusion or dizziness, severe vomiting, worsening of previous flu symptoms, or chest or abdominal pain, you should not wait to contact your doctor but should seek emergency medical care.

Last Editorial Review: 4/27/2009
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR