Dysentery is an intestinal infection that causes diarrhea containing blood or mucus. Symptoms can also include stomach cramps, nausea, vomiting, and fever. It can result from a bacterial or parasitic infection, often due to poor hygiene or sanitation.

In the United States, most cases of dysentery are mild. However, some people may experience severe symptoms and complications of the disease.

This article describes what dysentery is, including its symptoms, causes, treatment options, and possible complications. We also provide information on diagnosis and prevention.

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Dysentery refers to bloody diarrhea, which can sometimes also contain mucus. It can occur due to infectious germs, parasites, and irritation of the gut from chemicals.

The most common type of infection dysentery is bacillary dysentery, or shigellosis. This type is due to infection with the Shigella bacteria.

Another main type of dysentery is amebic dysentery, or amebiasis. This type is due to infection with a single-cell parasite called Entamoeba.

In the U.S., most people who develop dysentery experience only mild symptoms that disappear within a few days. However, dysentery is a notifiable disease, meaning a person must inform the authorities if they have it. Doing so helps to prevent an outbreak of dysentery.

Dysentery symptoms differ according to whether the infection is bacterial or parasitic.

Symptoms of bacillary dysentery

According to the Centers for Disease Control and Prevention (CDC), symptoms of bacillary dysentery typically begin around 1–2 days after infection and last around 7 days.

Symptoms may include:

  • diarrhea, which can contain blood
  • feeling the need to pass stool even when the bowels are empty
  • abdominal pain
  • fever

Symptoms typically last around 5–7 days, though some people may experience symptoms for 4 weeks or more. In some cases, it may take several months for a person’s bowel habits to return to normal.

Antibiotics can shorten the duration of illness by a couple of days and may prevent the infection from spreading to others. However, people typically only receive antibiotics if their symptoms are severe.

Symptoms of amebic dysentery

A person with amebic dysentery may experience the following symptoms:

A doctor may prescribe medications to help eradicate the parasitic infection.

There are two main types of dysentery, and each has different causes. We outline these below.

Bacillary dysentery, or shigellosis

The bacteria Shigella causes bacillary dysentery. A person may contract Shigella in the following ways:

  • not washing their hands thoroughly after visiting the bathroom
  • touching surfaces that the bacteria have contaminated, and then touching their mouth, nose, or eyes
  • eating food that the bacteria have contaminated
  • swallowing lake or river water when swimming
  • having sexual contact with someone who is recovering from bacillary dysentery

Shigella bacteria may remain in a person’s stool for 1–2 weeks after they stop experiencing symptoms of the infection. People should continue to follow strict hygiene practices to prevent passing the infection on to others.

Shigella outbreaks can occur among small social or community groups, including childcare facilities.

Amebic dysentery, or amebiasis

The parasite Entamoeba causes amebic dysentery.

Most cases of amebic dysentery occur when people ingest food or water contaminated with feces containing Entamoeba eggs.

People most at risk of developing severe amebic dysentery include:

  • women who are pregnant or postpartum
  • newborns
  • people who are taking corticosteroids
  • people who are malnourished
  • people who are living with cancer

Certain conditions can cause symptoms similar to those of dysentery. Examples include:

  • Escherichia coli infection: A type of bacterial infection. Outbreaks are typically due to people consuming raw or undercooked foods or foods contaminated with feces. Symptoms may include:
    • abdominal cramps
    • diarrhea, which may contain blood
    • vomiting
    • fever
  • Hookworm infection: A parasitic infection that can cause bloody diarrhea. Hookworm infections are more common in countries with warm, moist climates and poor sanitation. The main mode of transmission is walking barefoot on contaminated soil. People with a mild infection may not experience any symptoms. Itching and a localized rash are often the first signs of infection. Those with severe infection may experience the following:
  • Antibiotic use: Antibiotic use may lead to overgrowth of the bacteria Clostridiodes difficile. This can result in inflammation of the large intestine, known as pseudomembranous colitis (PC). Symptoms of PC include:
    • abdominal cramping
    • diarrhea
    • fever

Laboratory tests will reveal whether dysentery is due to Shigella or Entamoeba infection or another cause. A doctor will use this information when deciding which treatment to prescribe.

In general, a person with diarrhea or vomiting should drink plenty of fluids to prevent dehydration. People who experience severe dehydration may require intravenous fluid replacement.

Treatment for mild bacillary dysentery

As dysentery usually gets better on its own after 3–7 days, people do not usually need treatment. If the person has diarrhea, they should drink plenty of fluids to avoid dehydration. If the diarrhea is bloody, they should avoid taking anti-diarrheal medication.

A doctor may prescribe antibiotics if diarrhea and other symptoms are severe.

Treatment for amebic dysentery

People who have amebic dysentery may receive medications to eliminate the parasitic infection. Medication may include a combination of metronidazole and tinidazole.

In rare cases, people can develop complications of amebic dysentery, such as intestinal issues or liver abscesses. A person may require surgery to address these issues.

A person who experiences severe symptoms of dysentery should see their doctor for a diagnosis and appropriate treatment.

In order to diagnose dysentery, a doctor may:

  • ask about the person’s symptoms and when they started
  • ask if the person has recently traveled abroad
  • carry out a physical examination

If a person has recently returned from abroad, they may have to provide one or more stool samples. If they have suspected amebic dysentery and their stool samples test negative for the parasite, they may need to undergo a colonoscopy to examine the mucosal surface of the intestines.

A person who has a suspected liver abscess may require aspiration of their liver fluid to help diagnose the abscess.

If a person’s symptoms continue, their doctor may recommend diagnostic imaging of the intestines, such as an ultrasound scan or an endoscopy.

Dysentery can cause medical complications. These are more common among people with compromised immune systems.

Some potential complications of dysentery include:

  • Dehydration: Frequent diarrhea and vomiting can lead to dehydration. In infants and young children, this can quickly become life-threatening.
  • Liver abscess: Amebic dysentery can cause an abscess in the liver.
  • Postinfectious arthritis (PIA): A person may develop PIA as a complication of Shigella infection. Symptoms include joint pain, inflammation, and stiffness.
  • Hemolytic uremic syndrome: A condition involving inflammation and damage to the small blood vessels within the kidneys. It is a rare complication of Shigella infection.

A person who suspects that they are developing complications from dysentery should seek medical attention as soon as possible.

Dysentery outbreaks usually occur as a result of poor hygiene or sanitation. To reduce the risk of infection, people should wash their hands regularly with soap and water, especially after using the bathroom and before preparing food.

The risk of contracting dysentery is higher for people traveling to countries with warm, moist climates and poor sanitation. When traveling to such places, a person should:

  • only drink reliably sourced water, such as bottled water
  • ensure that bottled water has an unbroken seal before drinking
  • avoid ice cubes, as the water may be from a contaminated source
  • use only bottled or purified water to clean the teeth
  • cook food thoroughly before eating

A person may develop dysentery due to poor hygiene habits or after traveling to areas with poor sanitation. Mild symptoms should resolve without treatment.

However, people who develop severe symptoms should see a doctor. Treatment may be necessary to prevent possible complications.

A person should contact a doctor if they experience any of the following:

  • abdominal pain that is severe or unbearable
  • a high fever of 102 degrees or higher
  • diarrhea that has lasted longer than two or three days
  • signs of dehydration, which may include:

Dysentery is infection and inflammation of the intestines, which causes diarrhea that may contain blood or mucus. Other possible symptoms include abdominal pain, nausea and vomiting, and fever.

Dysentery can occur as a result of bacterial or parasitic infections.

Dysentery outbreaks are more common in countries with hot, moist climates and poor sanitation. A person can help prevent dysentery by taking appropriate precautions when traveling to high-risk areas and practicing good hygiene.

In the U.S., most cases of dysentery are mild and do not require treatment. However, people who experience severe symptoms should see their doctor for a diagnosis and appropriate treatment. Doing so reduces the risk of possible complications.