There are a number of bacteria, viruses, and parasites that cause gastrointestinal (GI) infections. According to the U.S. Centers for Disease Control and Prevention, diarrheal diseases account for 1 in 9 child deaths worldwide. It affects 2,195 children every day — more than AIDS, malaria, and measles combined.

Although they can continue for as long as 14 days, GI infections usually last a few days. They’re characterized by abdominal cramps and discomfort followed by diarrhea. Other symptoms might include:

Here are a few common types of GI infections.

Bacterial

  • E. coli. E. coli bacteria are found in the intestines of people and animals. Most varieties are harmless, but some strains — such as E. coli O157:H7 — secrete a toxin that can cause abdominal cramps, vomiting, and bloody diarrhea. E. coli spread through contaminated water or food that came into contact with animal manure. E. coli can also spread through direct person-to-person contact.
  • Salmonella. Salmonella infection is commonly caused by eating raw or undercooked poultry, meat, and eggs. The majority of salmonella infections can be classified as gastroenteritis.

Viral

  • Norovirus. Noroviruses are the most common cause of foodborne illness worldwide. It’s especially likely to spread among people in confined spaces. Although in most cases the virus is spread through contaminated food or water, person-to-person transmission is also possible.
  • Rotavirus. According to the Mayo Clinic, rotavirus is the leading cause of viral gastroenteritis in children worldwide. Children are commonly infected when they touch objects contaminated with the virus and then put their fingers in their mouths. There’s a rotavirus vaccine available in some countries.

Parasite

  • Giardiasis. Giardia is a parasite that spreads easily through human contact and contaminated water. It’s resistant to chlorine and can spread in public swimming pools. Infection can occur from drinking water from and bathing in contaminated lakes and streams.
  • Cryptosporidiosis. A leading cause of waterborne disease in the United States, Cryptosporidium is a microscopic parasite which causes cryptosporidiosis. It has an outer shell that helps it survive outside of a host and tolerate chlorine disinfection.

Adults

See your doctor right away if you:

  • have a fever above 104°F (40°C)
  • have an inability to keep liquids down for 24 hours
  • are vomiting for more than 48 hours
  • are vomiting blood
  • are becoming dehydrated: excessive thirst, dry mouth, little or no urine (or deep yellow urine), extreme weakness, lightheadedness or dizziness
  • have blood in your bowel movements

Children

See your pediatrician right away if your child:

  • has a fever of above 102°F (39°C)
  • is experiencing a lot of discomfort or pain
  • appears lethargic
  • is very irritable
  • has bloody diarrhea
  • appears dehydrated

To tell if your child is dehydrated, you can monitor how much they’re drinking and urinating and compare to their typical amount.

Infants

Get your baby to their pediatrician right away if they:

  • have been vomiting (not just normal spitting up) for more than several hours
  • have a dry mouth
  • haven’t had a wet diaper in six hours
  • cries without tears
  • has severe diarrhea
  • has bloody stools
  • is unresponsive
  • is unusually drowsy or sleepy
  • has a sunken soft spot on the top of their head

In most cases, self-care measures are the recommended treatment. Antibiotics will not help GI infections from viruses or parasites.

Although antibiotics can help with complicated cases of bacterial infection, in uncomplicated cases, antibiotics may actually prolong the condition and increase risk of relapse.

Additionally, in certain infections, antibiotics may lead to dangerous complications. Your doctor can help determine if you or your child need antibiotics.

Your doctor might recommend that you stay away from high-fiber foods that could make diarrhea worse. They might also recommend over-the-counter medications that neutralize stomach acid or that treat nausea, abdominal pain, and diarrhea.

The most important self-care treatment for adults and children with a GI infection is to stay hydrated.

Gastrointestinal infections are caused by a number of bacteria, viruses, and parasites. In many cases, the infection will pass in a few days.

If you or your child have symptoms such as high fever, bloody bowel movements, or vomiting, see your doctor for a full diagnosis and treatment plan.