Dysentery is an intestinal infection that causes severe diarrhea with blood. In some cases, mucus may be found in the stool. This usually lasts for 3 to 7 days.

Other symptoms may include:

  • abdominal cramps or pain
  • nausea
  • vomiting
  • fever of 100.4°F (38°C) or higher
  • dehydration, which can become life-threatening if left untreated

Dysentery is usually spread as a result of poor hygiene. For example, if someone who has dysentery doesn’t wash their hands after using the toilet, anything they touch is at risk.

The infection is also spread through contact with food or water that has been contaminated with fecal matter. Careful hand washing and proper sanitation can help prevent dysentery and keep it from spreading.

Most people who experience dysentery develop either bacterial dysentery or amebic dysentery.

Bacterial dysentery is caused by infection with bacteria from Shigella, Campylobacter, Salmonella, or enterohemorrhagic E. coli. Diarrhea from Shigella is also known as shigellosis. Shigellosis is the most common type of dysentery, with about 500,000 cases diagnosed in the United States each year.

Amebic dysentery is caused by a single-celled parasite that infects the intestines. It’s also known as amebiasis.

Amebic dysentery is less common in the developed world. It’s usually found in tropical locales that have poor sanitary conditions. In the United States, most cases of amebic dysentery occur in people who have traveled to an area where it’s common.

Shigellosis and amebic dysentery typically result from poor sanitation. This refers to environments where people who don’t have dysentery come into contact with fecal matter from people who do have dysentery.

This contact may be through:

  • contaminated food
  • contaminated water and other drinks
  • poor hand washing by infected people
  • swimming in contaminated water, such as lakes or pools
  • physical contact

Children are most at risk of shigellosis, but anyone can get it at any age. It’s easily spread through person-to-person contact and by contaminated food and drink.

Shigellosis mostly spreads among people who are in close contact with an infected person, such as people:

  • at home
  • in day care centers
  • in schools
  • in nursing homes

Amebic dysentery is primarily spread by eating contaminated food or drinking contaminated water in tropical areas that have poor sanitation.

If you or your child has symptoms of dysentery, see your doctor. If left untreated, dysentery can lead to severe dehydration and become life-threatening.

At your appointment, your doctor will review your symptoms and any recent travels. You should note any travels outside of the country. This information can help your doctor narrow down the possible cause of your symptoms.

Many conditions can cause diarrhea. If you don’t have other symptoms of dysentery, your doctor will order diagnostic testing to determine which bacteria are present. This includes a blood test and a lab test of a stool sample.

Your doctor may also perform addition testing to decide whether an antibiotic will help.

Mild shigellosis is usually treated just with rest and plenty of fluids. Over-the-counter medication, such as bismuth subsalicylate (Pepto-Bismol), can help relieve cramps and diarrhea. You should avoid drugs that slow down the intestines, such as loperamide (Imodium) or atropine-diphenoxylate (Lomotil), which can make the condition worse.

Severe shigellosis can be treated with antibiotics, but the bacteria that causes it are often resistant. If your doctor prescribes an antibiotic and you don’t see improvement after a couple of days, let the doctor know. Your strain of Shigella bacteria may be resistant, and your doctor may need to adjust your treatment plan.

Amebic dysentery is treated with metronidazole (Flagyl) or tinidazole (Tindamax). These drugs kill the parasites. In some cases, a follow-up drug is given to make sure all the parasites are gone.

In severe cases, your doctor may recommend an intravenous (IV) drip to replace fluids and prevent dehydration.

In some cases, dysentery can lead to complications. These include:

Postinfectious arthritis: This affects about 2 percent of people who get a particular strain of the Shigella bacteria called S. flexneri. These people can develop joint pain, eye irritation, and painful urination. Postinfectious arthritis can last for months or years.

Blood stream infections: These are rare and most likely to affect people with weak immune systems, such as people with HIV or cancer.

Seizures: Sometimes young children can have generalized seizures. It isn’t clear why this happens. This complication generally resolves without treatment.

Hemolytic uremic syndrome (HUS): One type of Shigella bacteria, S. dysenteriae, can sometimes cause HUS by making a toxin that destroys red blood cells.

In rare cases, amebic dysentery can result in liver abscess or parasites spreading to the lungs or brain.

Shigellosis usually goes away within a week or so and doesn’t require prescription medications. If you have shigellosis, avoid preparing food for other people and don’t go swimming. People who have shigellosis and work with children, in food preparation, or in healthcare should stay home until the diarrhea has stopped. If you or a partner has shigellosis, avoid having sex until the diarrhea has stopped.

Most people with amebic dysentery are sick for anywhere from a few days to several weeks. If you suspect amebic dysentery, it’s important to get immediate medical attention. Your doctor must prescribe medication to get rid of the parasite that causes this type of dysentery.

Shigellosis can be prevented through good sanitation practices, such as:

  • frequent hand washing
  • being careful when changing a sick baby’s diaper
  • not swallowing water when swimming

The best way to prevent amebic dysentery is to be careful about what you eat and drink while visiting an area where it’s common. When travelling to these areas, you should avoid:

  • drinks with ice cubes
  • drinks that aren’t bottled and sealed
  • food and beverages sold by street vendors
  • peeled fruit or vegetables, unless you peel them yourself
  • unpasteurized milk, cheese, or dairy products

Safe sources of water include:

  • bottled water, if the seal is unbroken
  • carbonated water in cans or bottles, if the seal is unbroken
  • soda in cans or bottles, if the seal is unbroken
  • tap water that has been boiled for at least one minute
  • tap water that has been filtered through a 1-micron filter with chlorine or iodine tablets added