What Is the Flu?
How are stomach flu and influenza different?
"Stomach flu" is a popular term, but not a true medical diagnosis. It's not uncommon to mistake gastroenteritis, which is what stomach flu is, for the viral infection we commonly call the "flu." Gastroenteritis refers to inflammation of the gastrointestinal tract (stomach and intestines). Viruses are the most common cause of stomach flu. With gastroenteritis, you may have symptoms such as abdominal cramps, nausea, vomiting, and diarrhea.
For more about gastrointestinal flu, read WebMD's Stomach Flu or Influenza?
How is flu spread?
The flu virus is spread from person to person through respiratory secretions and typically sweeps through large groups of people who spend time in close contact, such as in daycare facilities, classrooms, college dormitories, military barracks, offices, and nursing homes.
Flu is spread when you inhale droplets in the air that contain the flu virus, make direct contact with respiratory secretions through sharing drinks or utensils, or handle items contaminated by an infected person. In the latter case, the flu virus on your skin can infect you when you touch or rub your eyes, nose, or mouth. That's why frequent and thorough handwashing is a key way to limit the spread of influenza. Flu symptoms start to develop from one to four days after infection with the virus.
Who's at greatest risk for flu complications?
While anyone can get flu, infants, the elderly, pregnant women, and people with chronic ailments such as diabetes, heart disease, lung disease, and HIV are at highest risk for flu complications. Despite advances in flu prevention and treatment, the CDC estimates that deaths related to influenza range from 3,000 to 49,000 deaths in the United States each year.
Specific strains of flu can be prevented by a flu vaccine, either a flu shot or nasal spray flu vaccine. In addition, antiviral medications are available to prevent flu. These drugs may help reduce the severity and the duration of flu and are best used within the first 48 hours of the appearance of flu symptoms.
For in-depth information, see WebMD's Flu Complications.