Influenza, commonly called the flu, is caused by a virus. Every year there is a flu season, usually in the fall and winter. You may have had the flu, or know someone who has had it.

The flu is a respiratory disease. Symptoms include fever, runny nose, sneezing, cough and muscle aches.

Anyone can get the flu. In healthy adults it usually doesn't cause serious illness. For the very young, the elderly, and those who are already sick, the flu may cause complications and result in more serious illness. One of the most common complications is pneumonia. Every year there are deaths in the U.S. as a result of flu complications.

The flu virus can be spread through the air when a sick person coughs or sneezes. Then the microscopic (invisible) virus particles can be inhaled through the nose or mouth of another person. The virus particles may also fall onto a surface where they can be picked up on someone's hands and transferred to their nose or mouth by touching. (See the section "Staying Healthy And Avoiding the Flu" to learn how you can lessen your chances of getting the flu.)

Flu vaccinations are offered every year - and you should get one. This vaccine helps prevent seasonal flu. Common sense precautions such as washing you hands and sneezing into a tissue will help prevent the spread of the flu.

No, the viruses that typically cause seasonal flu are not in our food.

No. Seasonal flu occurs every year, and there are vaccines available to help protect us from these flu viruses. A pandemic is quite different - see the section on "Pandemic Flu" to understand how these are different.