Like people, pigs can get influenza (flu), but swine flu viruses aren't the same as human flu viruses. Swine flu doesn't often infect people, and the rare human cases that have occurred in the past have mainly affected people who had direct contact with pigs.
But the current swine flu outbreak is different. It's caused by a new swine flu virus that has spread from person to person -- and it's happening among people who haven't had any contact with pigs.
Symptoms of swine flu are like regular flu symptoms and include fever, cough, sore throat, body aches, headache, chills, and fatigue. Some people have reported diarrhea and vomiting associated with swine flu.
Those symptoms can also be caused by many other conditions, and that means that you and your doctor can't know, just based on your symptoms, if you've got swine flu. It takes a lab test to tell whether it's swine flu or some other condition.
The new swine flu virus apparently spreads just like regular flu. You could pick up germs directly from an infected person, or by touching an object they recently touched, and then touching your eyes, mouth, or nose, delivering their germs for your own infection.
That's why you should make washing your hands a habit, even when you're not ill. Infected people can start spreading flu germs up to a day before symptoms start, and for up to seven days after getting sick.
The swine flu virus can become airborne if you cough or sneeze without covering your nose and mouth, sending germs into the air.
The U.S. residents infected with swine flu virus had no direct contact with pigs. The CDC says it's likely that the infections represent widely separated cycles of human-to-human infections.
The new swine flu virus is sensitive to the antiviral drugs Tamiflu and Relenza. The CDC recommends those drugs to prevent or treat swine flu; the drugs are most effective when taken within 48 hours of the start of flu symptoms.
Wash your hands regularly with soap and water, especially after coughing or sneezing. Or use an alcohol-based hand cleaner.
Avoid close contact with sick people.
Avoid touching your mouth, nose, or eyes
You can't get swine flu by eating pork, bacon, or other foods that come from pigs.
The U.S. government has declared swine flu to be a public health emergency.
It remains to be seen how severe swine flu will be in the U.S. and elsewhere, but countries worldwide are monitoring the situation closely and preparing for the possibility of a pandemic.
The World Health Organization has not declared swine flu to be a pandemic. The WHO wants to learn more about the virus first and see how severe it is and how deeply it takes root.
But it takes more than a new virus spreading among humans to make a pandemic. The virus has to be able to spread efficiently from one person to another, and transmission has to be sustained over time. In addition, the virus has to spread geographically.