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Amoebiasis - Symptoms of dysentery

NHS Choices Medical Reference

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In the UK, most people who get dysentery only have mild symptoms which often clear up within a few days.

Bacillary dysentery

Dysentery that is caused by shigella bacteria (bacillary dysentery or shigellosis) is the most common type of dysentery in the UK.

Symptoms of bacillary dysentery usually begin one to seven days after infection. Common symptoms are mild stomach pains and bloody diarrhoea. These symptoms last for three to seven days and many people do not need to visit their GP.

There is usually a lot of diarrhoea to begin with, followed by smaller amounts that are passed frequently and sometimes painfully.

In more severe cases, symptoms can include:

  • watery diarrhoea that contains blood or mucus
  • nausea or vomiting (feeling or being sick) 
  • severe abdominal pain
  • stomach cramps
  • a high temperature (fever) of 38C (100.4F) or over

Amoebic dysentery

Dysentery that is caused by an amoeba (a single-celled parasite) is called amoebic dysentery or amoebiasis. Amoebic dysentery mainly occurs in tropical areas.

In some cases, amoebic dysentery does not cause any symptoms. However, an infected person will pass cysts (amoebas that are surrounded by a protective wall) in their stools when they go to the toilet, and can infect their surroundings (see causes of dysentery for more information).

If you do experience symptoms, they may start up to 10 days after you originally became infected. Symptoms of amoebic dysentery include:

  • watery diarrhoea, which can contain blood
  • mucus or pus
  • nausea
  • vomiting
  • abdominal pain
  • fever and chills
  • bleeding from your rectum (back passage)
  • loss of appetite and weight loss

If you have amoebic dysentery, it is likely you will have blood in your diarrhoea. This is because the amoebas attack the walls of the large intestine, causing ulcers (sores) to develop that can bleed. The passing of stools may be painful.

Occasionally, the parasite can enter the bloodstream and spread to other organs in the body, particularly the liver, leading to the formation of an abscess (liver abscess). Symptoms of a liver abscess include:

  • fever and weakness
  • abdominal swelling and pain 
  • cough 
  • nausea (feeling sick)
  • jaundice
  • loss of appetite
  • weight loss  

The symptoms of amoebic dysentery usually last a few days to several weeks. However, without treatment, even if the symptoms disappear, the amoebas can continue to live in the bowel for months or even years. This means that the infection can still be passed on to other people and that the diarrhoea can return.

Medical Review: March 26, 2013
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