Gastroenteritis

Gastroenteritis is an inflammation of the lining of the intestines caused by a virus, bacteria or parasites. Gastroenteritis can also be caused by ingestion of chemical toxins or drugs.

The cause is more often due to norovirus infection. It is spread through food or water that has been contaminated as well as through contact with an infected person.

Symptoms of gastroenteritis include nausea, diarrhea, abdominal cramping, vomiting, headache, fever and chills.

Most people can recover without receiving treatment and most people will get better in 1 to 3 days.

Antibiotics will not help if you have norovirus illness since antibiotics fight against bacteria, not viruses. However, antibiotics can be used to treat gastroenteritis caused by some bacteria.

Antiparasitic medications, such as metronidazole and nitazoxanide, can be given to treat parasitic infections.

The most common problem associated with gastroenteritis is dehydration. Dehydration can occur if you do not drink enough fluids to replace what is lost through vomiting and diarrhea. Babies, young children, the elderly and people with weak immune systems are at a higher risk for dehydration.

Gastroenteritis may be caused by viruses, bacteria, or parasites. Gastroenteritis can also be caused by ingestion of chemical toxins or drugs.

Viruses:

The cause of gastroenteritis is mostly due to norovirus infection. Norovirus, can spread quickly especially in crowded, closed places like nursing homes, daycare centers, schools, and cruise ships. Norovirus can also cause outbreaks in restaurants and if food is contaminated.

Other possible causes include:

• Rotavirus
• Astrovirus 
• Enteric adenovirus

Since the viruses are found in the vomit and stool of infected people, you can get gastroenteritis by:

• Eating contaminated food or liquids
• Touching your mouth after touching a contaminated object
• Having direct contact with a person who is infected

People with norovirus are contagious from the time they begin feeling sick until at least 3 days after they recover. Some people may be contagious for even longer.

Bacteria:

Salmonella and Campylobacter are the most common bacterial causes of diarrhea in the United States. Both infections are most frequently acquired from undercooked poultry as well as with unpasteurized milk.

Other possible causes include:

• Shigella
• Escherichia coli (E. coli)

Parasites:

• Giardia intestinalis is more common in cold climates but occurs in every region of the United States and throughout the world
• Cryptosporidium parvum

Chemical Gastroenteritis

Gastroenteritis may result from ingesting chemical toxins such as poisonous mushrooms or by certain kinds of exotic seafood. Gastroenteritis can also be caused by ingesting water or food contaminated by chemicals such as arsenic, lead, mercury, or cadmium. In addition, eating large amounts of acidic foods, such as citrus fruits and tomatoes, can cause gastroenteritis in some people.

Most cases improve on their own with fluids. See your doctor for signs of dehydration, high fever, blood in the stool, or symptoms lasting more than a few days, and seek care urgently for severe abdominal pain or inability to keep fluids down.