An intestinal infection that causes diarrhoea and may spread to the liver
The intestinal infection amoebiasis is caused by the protozoan parasite Enta-moeba histolytica. Worldwide, the disease is very common, affecting about 500 million people. It is mostly contracted in developing countries in the tropics. Usually, infection results from drinking water or eating food contaminated with the parasite, which is excreted in the faeces of infected people. In severe cases, ulcers develop in the walls of the intestine, and the condition is then known as amoebic dysentery.
Most infected people do not develop symptoms or have only mild, intermittent symptoms, which may include:
Mild abdominal pain.
If you develop amoebic dysentery, the symptoms usually first appear between 5 days and several weeks after the initial infection. Symptoms may include:
Watery, bloody diarrhoea.
Severe abdominal pain.
In some cases, dehydration and anaemia may develop. In addition, there is a risk of infection spreading through the bloodstream to the liver, causing high fever, painful liver abscesses, extreme tiredness, and loss of appetite.
Diagnosis of amoebiasis is usually made from examination of a sample of faeces under a microscope to look for the parasite. Your doctor may also arrange for you to have a blood test to look for antibodies that are produced by the body in response to the parasite. If your doctor suspects that you have liver abscesses, he or she will arrange for you to have imaging tests, such as CT scanning or ultrasound scanning. Amoebiasis can be successfully treated with antibiotics, which usually kill the parasite within a few days. With drug treatment, most affected people make a full recovery from the infection within a few weeks.
There are several preventive measures you can take against amoebiasis if you visit a region where the disease is common. You should drink only bottled or thoroughly boiled water to be certain that it is safe (see Travel health). You should also avoid eating raw vegetables, salads, or fruits with skins that cannot be peeled because their skins may be contaminated with the parasite.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.