Viral gastroenteritis affects people in all parts of the world. Each virus has its own seasonal activity. For example, in the United States, rotavirus and astrovirus infections occur during the cooler months of the year (October to April), whereas adenovirus infections occur throughout the year.

Gastroenteritis means inflammation of the stomach and small and large intestines. Viral gastroenteritis is an infection caused by a variety of viruses that results in vomiting or diarrhea. It is often called the "stomach flu," although it is not caused by the influenza viruses.

Many different viruses can cause gastroenteritis, including rotaviruses, noroviruses, adenoviruses,type 40 or 41, sapoviruses, and astroviruses. Viral gastroenteritis is not caused by bacteria (such as Salmonella or Escherichia coli) or parasites (such as Giardia), or by medications or other medical conditions, although the symptoms may be similar. Your doctor can determine if the diarrhea is caused by a virus or by something else.

The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. The affected person may also have headache, fever, and abdominal cramps ("stomach ache"). In general, the symptoms begin 1 to 2 days following infection with a virus that causes gastroenteritis and may last for 1 to 10 days, depending on which virus causes the illness.

For most people, it is not. People who get viral gastroenteritis almost always recover completely without any long-term problems. Gastroenteritis is a serious illness, however, for persons who are unable to drink enough fluids to replace what they lose through vomiting or diarrhea. Infants, young children, and persons who are unable to care for themselves, such as the disabled or elderly, are at risk for dehydration from loss of fluids.

Anyone can get it. Viral gastroenteritis occurs in people of all ages and backgrounds. However, some viruses tend to cause diarrheal disease primarily among people in specific age groups. Rotavirus and norovirus infections are the most common cause of diarrhea in infants and young children under 5 years old. Adenoviruses and astroviruses cause diarrhea mostly in young children, but older children and adults can also be affected.

Generally, viral gastroenteritis is diagnosed by a physician on the basis of the symptoms and medical examination of the patient. Rotavirus infection can be diagnosed by laboratory testing of a stool specimen. Tests to detect other viruses that cause gastroenteritis are not in routine use, but the viral gastroenteritis unit at CDC can assist with special analysis upon request.

The most important of treating viral gastroenteritis in children and adults is to prevent severe loss of fluids (dehydration). This treatment should begin at home. Your physician may give you specific instructions about what kinds of fluid to give. CDC recommends that families with infants and young children keep a supply of oral rehydration solution (ORS) at home at all times and use the solution when diarrhea first occurs in the child. ORS is available at pharmacies without a prescription.

Persons can reduce their chance of getting infected by frequent handwashing, prompt disinfection of contaminated surfaces with household chlorine bleach-based cleaners, and prompt washing of soiled articles of clothing. If food or water is thought to be contaminated, it should be avoided.

Currently there is a licensed rotavirus vaccine available that protects against severe diarrhea from rotavirus infection in infants and young children. Studies into a norovirus vaccine are underway.

Infections causing gastroenteritis can be spread by contaminated food or water or through an infected food handler. Individuals who are symptomatic with gastroenteritis can spread illness to others by touching handrails, elevator buttons, and shared utensils, as well as through direct intimate contact with others while they are ill.

CWD is relatively rare. In Colorado, for example, fewer than 200 cases, mostly in mule deer, have been documented since 1981. In checking hunter-harvested animals, less than 6% of deer and 1% of elk in north-central and northeastern Colorado were found to have CWD. Similar surveillance in southeastern Wyoming also indicated that less than 7% of deer had CWD. Deer and elk checked outside these areas in Colorado and Wyoming did not have CWD.

Gastrointestinal illness (gastroenteritis) is the inflammation of the stomach and small and large intestines. The main symptoms include vomiting and watery diarrhea. Other symptoms include fever, abdominal cramps, nausea, and headache. Infections causing gastroenteritis can be viral, bacterial, or parasitic in origin. Norovirus is a common cause of viral gastroenteritis found on cruise ships. Types of bacterial gastroenteritis infections include Escherichia coli and salmonella.

Food may be contaminated by food preparers or handlers who have viral gastroenteritis, especially if they do not wash their hands regularly after using the bathroom. Shellfish may be contaminated by sewage, and persons who eat raw or undercooked shellfish harvested from contaminated waters may get diarrhea. Drinking water can also be contaminated by sewage and be a source of spread of these viruses.

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