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Digestive health centre

Dysentery: Amoebic dysentery

Dysentery is an infection of the intestines causing diarrhoea that contains blood or mucus.

There are two main types of dysentery:

  • Shigellosis, or bacillary dysentery, is the most common type experienced in the UK, caused by the shigella bacteria.
  • Amoebic dysentery, also called amoebiasis, is caused by a single-celled parasite called Entamoeba histolytica. This form of dysentery is more common abroad in tropical countries.

This article focuses on amoebic dysentery, This is usually caused by poor hygiene or contaminated food or water. Amoebic dysentery is a notifiable disease, so your GP must let the local health authority know if you have contracted it.

Causes of amoebic dysentery

Once inside the body, amoeba clump together to form a cyst that is protected by the stomach’s digestive acid. When the cyst passes through the intestines it breaks open infecting the body. The amoebae burrow into the intestinal wall and cause small ulcers or abscesses. Cysts exit the body via faeces but are still able to live outside, which is how many people become infected.

Severe dysentery is more common in developing countries due to compromised hygiene. You can get sick in a number of ways including:

  • Eating contaminated food
  • Drinking contaminated water
  • Contracting dysentery from another infected person.

Symptoms of amoebic dysentery

Symptoms can appear as many as 10 days after exposure and infection by the parasite. Signs of infection include:

Complications of amoebic dysentery

If the parasite gets into your bloodstream it can spread to other parts of your body, including the liver. When this happens you run the risk of developing a liver abscess. Symptoms include:

Symptoms can last from a few days to a few weeks. Untreated, even if symptoms go away, parasites can live in the bowel for months or years.

Diagnosing amoebic dysentery

If you show the above symptoms of amoebic dysentery or if you have diarrhoea with blood or mucus, you should seek medical advice.

The doctor may:

  • Request a stool (poo) sample to check for bacteria or parasites
  • Arrange an ultrasound if a liver abscess is suspected
  • Carry out a blood test for antibodies
  • Arrange a colonoscopy to check the bowels.

Tell the doctor if you have been abroad. Because amoebic dysentery is a notifiable disease, your doctor will notify local authorities if you test positive for the parasites. This is so they can identify the cause and take steps to protect others from infection if necessary.


Who is more at risk?

The risk of contracting amoebic dysentery is higher if you:

  • Live in crowded conditions (such as in an army barracks)
  • Live in insanitary conditions
  • Live where water is unclean
  • Live where sewage disposal is inadequate
  • Live where human faeces are used as fertiliser
  • Don’t thoroughly wash your hands often
  • Have a weak immune system
  • Have oral or anal sex.

WebMD Medical Reference

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