With symptoms like diarrhea, cramps, vomiting, and more, it can seem like nothing is worse than the stomach flu. This common illness, also called viral gastroenteritis, spreads quickly, which gives you another reason to stay at home for a few days until you feel better. Here’s a look at what causes that unwelcome stomach bug—and it may not be what you think.
What causes the stomach flu?
There are several different viruses that can cause the stomach flu. These viruses are most active during October through April.
- Norovirus: This virus can affect all ages, but is more common in adults, causing about 50% to 70% of stomach flu cases. Because the virus is highly contagious, it spreads quickly through families and communities, especially among groups in small spaces. You can become infected by touching a contaminated surface, eating contaminated food, or drinking contaminated water that has been prepared, touched, or handled by an infected person.
- Rotavirus: This virus is the most common cause of stomach flu in children. They become infected by putting their fingers in their mouth after touching contaminated objects. While adults may not experience symptoms, they can still spread the illness. Infants and young children generally experience a more severe rotavirus infection. Fortunately, there is a vaccine for children that protects against the rotavirus.
- Astrovirus: This is another virus that causes gastroenteritis, affecting young children around the world. The virus has been known to also affect the elderly and immunocompromised individuals as well, but is the third most frequent cause of gastroenteritis in babies. Transmission of the virus is usually through fecal-oral route—when fecal particles are passed from one host and introduced into the oral cavity of another host.
- Adenovirus: This virus is a respiratory infection that affects infants and young children more often than adults. Although primarily a respiratory illness, the virus can cause other illnesses such as gastroenteritis.
What doesn't cause the stomach flu?
Despite the name, influenza isn’t to blame for your stomach bug. The "real" flu is a virus that attacks the respiratory system, specifically your nose and throat. The stomach flu, however, is an infection that attacks your intestines, causing swelling and inflammation.
What are stomach flu risk factors?
Stomach flu affects everyone, but some are more vulnerable to the intestinal infection. They include:
- The elderly: Older adults have a less efficient immune system. Because of their weak immune systems, they are more vulnerable.
- Young children: Younger children have immune systems that have not yet fully developed, so they are more vulnerable to infection as well.
- Immunocompromised individuals: People who have a weakened immune systems due to chemotherapy, HIV/AIDS, or another medical condition, are especially at risk for the stomach flu.
- People in confined spaces: Stomach flu spreads quickly through groups in close contact with one another. This means schoolchildren, churchgoers, and college students who live in dormitories are at an increased risk for contracting the virus.
