Updated: Apr 27, 2021

Dysentery is an infection of the intestines, primarily of the colon. It is characterized by inflammation of the intestine, abdominal pain, and diarrhoea with stools that often contain blood and mucus. Without adequate hydration, it can be fatal.

The World Health Organization (WHO) defines dysentery as any episode of diarrhoea in which blood is present in loose, watery stools.

Infection with the Shigella bacillus, or bacterium, is the most common cause.

Each year worldwide, there are between 120 million and 165 million cases of Shigella infection, of which 1 million are fatal. Over 60 percent of these fatalities are children under 5 years old in developing countries.


The World Health Organization (WHO) identifies two main causes of dysentery.

Bacillary dysentery, or shigellosis

This type produces the most severe symptoms. It is caused by the Shigella bacillus.

Poor hygiene is the main source. Shigellosis can also spread because of tainted food.

Amoebic dysentery, or amoebiasis

This type is caused by Entamoeba histolytica (E. histolytica), an amoeba.

When amoebae inside the bowel of an infected person are ready to leave the body, they group together and form a shell that surrounds and protects them. This group of amoebae is known as a cyst, which is then passed out of the person's body in the faeces and can survive outside the body.

In areas of poor sanitation, the amoebae can contaminate food and water and infect other humans, as they can survive for long periods outside the body.

They can also linger on people's hands after using the bathroom. Good hygiene practice reduces the risk of spreading infection.

If amoeba tunnel through the intestinal wall, they can spread into the bloodstream and infect other organs.

The amoebae may continue living within the human host after symptoms have gone. Then, symptoms may recur when the person's immune system is weaker.

Treatment reduces the risk of the amoebae surviving.

It is more common in the tropics.

Other causes

Other causes include a parasitic worm infection, chemical irritation, or viral infection.

Signs and Symptoms

The symptoms of dysentery range from mild to severe, largely depending on the quality of sanitation in the areas where infection has spread. Often, symptoms are so mild that a doctor's visit is not required, and the problem resolves in a few days.

In developed countries, signs and symptoms of dysentery tend to be milder than in developing nations or tropical areas.

Mild symptoms include:

  • a slight stomach-ache

  • cramps and bloating

  • flatulence (passing gas)

  • urgency to pass stool

  • feeling of incomplete emptying

  • loss of appetite

These usually appear from 1 to 3 days after infection, and the patient recovers within a week.

Less commonly, may be:

  • blood or mucus in the faeces

  • bleeding from your rectum

  • intense abdominal pain

  • fever

  • nausea

  • vomiting

  • weight loss

  • headache

  • the painful passing of stools

  • fatigue

  • intermittent constipation

Some people also develop lactose intolerance, which can last for a long time, sometimes years.


The doctor will ask the patient about their signs and symptoms and carry out a physical examination.

A stool sample may be requested.

If symptoms are severe, diagnostic imaging may be recommended. This could be an ultrasound scan or an endoscopy.


If treatment is necessary, it will depend on the diagnosis made.

Laboratory results will reveal whether the infection is due to Shigella or Entamoeba histolyca infection.

Though treatment is usually started without or before confirmation by laboratory analysis.

Any patient with diarrhoea or vomiting should drink plenty of fluids to prevent dehydration and can take oral rehydration solutions (ORS).

If they are unable to drink, or if diarrhoea and vomiting are profuse, intravenous (IV) fluid replacement may be necessary. The patient will be placed on a drip and monitored.

Treatment for mild bacillary dysentery

Mild bacillary dysentery, the kind commonly found in developed countries with good sanitation, will normally resolve without treatment.

However, the patient should drink plenty of fluids. In more severe cases, antibiotic drugs are available.

Treatment for amoebic dysentery

Amoebicidal medications are used to treat Entamoeba histolyca. These will ensure that the amoeba does not survive inside the body after symptoms have resolved.

Flagyl, or metronidazole, is often used to treat dysentery. It treats both bacteria and parasites.

If lab results are unclear, the patient may be given a combination of antibiotic and amoebicidal medications, depending on how severe their symptoms are.


With correct treatment, most cases of amoebic and bacterial dysentery subside within 10 days, and most individuals achieve a full recovery within two to four weeks after beginning proper treatment. If the disease is left untreated, the prognosis varies with the immune status of the individual patient and the severity of disease. Extreme dehydration can delay recovery and significantly raises the risk for serious complications.


Complications of dysentery are few, but they can be severe.

Dehydration: Frequent diarrhoea and vomiting can quickly lead to dehydration. In infants and young children, this can quickly become life-threatening.

Liver abscess: If amoebae spread to the liver, an abscess can form there.

Post-infectious arthritis: Joint pain may occur following the infection.

Hemolytic uremic syndrome: Shigella dysenteriae can cause the red blood cells to block the entrance to the kidneys, leading to anemia, low platelet count, and kidney failure.

Patients have also experienced seizures after infection.


Dysentery mostly stems from poor hygiene. Hand-washing is the most important way to stop the spread of infection. You're infectious to other people while you're ill and have symptoms.

To reduce the risk of infection, people should wash their hands regularly with soap and water, especially before and after using the bathroom and preparing food.

This can reduce the frequency of Shigella infections and other types of diarrhoea by up to 35 percent.

Other steps to take when the risk is higher, for example, when travelling (but not only), include:

  • Consider travelling with an alcohol-based hand sanitizer.

  • Only drink reliably sourced water, such as bottled water.

  • Watch the bottle being opened, and clean the top of the rim before drinking.

  • Avoiding swallowing water in swimming pools, hot tubs, or other recreational water sources.

  • Make sure food is thoroughly cooked.

  • Avoid fresh fruit or vegetables that can't be peeled before eating.

  • Avoid food and drink sold by street vendors, except drinks in properly sealed cans or bottles.

It is best to use purified water to clean the teeth, and avoid ice cubes, as the source of the water may be unknown.

Take the following steps to avoid passing the illness on to others:

  • Stay away from work or school until you've been completely free from any symptoms for at least 48 hours.

  • Help young children to wash their hands properly.

  • Don't prepare food for others until you've been symptom free for at least 48 hours.

  • Don't go swimming until you've been symptom free for at least 48 hours.

  • Wash all dirty clothes, bedding and towels on the hottest possible cycle of the washing machine.

  • Clean toilet seats and toilet bowls, and flush handles, taps and sinks with detergent and hot water after use, followed by a household disinfectant.

  • Avoid sexual contact until you've been symptom free for at least 48 hours.

Is Dysentery a Notifiable Disease?

Dysentery that is caused by Shigellosis is a notifiable disease. Public Health doctors need to know about an outbreak of dysentery so that they can try to identify the cause and, if necessary, take measures to prevent the condition spreading to other people.

....making effort to "STAY WELL"












Recent Posts

See All