Amoebiasis

Amoebiasis is an infection of the bowel caused by a parasite Entamoeba histolytica.

Amoebiasis isn't common in Aotearoa New Zealand and most people who get it have recently travelled to less-developed countries or have had contact with someone who has.

• When a person is infected, the parasite is in their poo and can easily infect others.
• Most people who have the parasite don't have symptoms, or have mild symptoms such as diarrhoea (runny poo), stomach pain, and stomach cramping.
• In rare cases, people can develop severe symptoms such as amoebic dysentery.
• Antibiotics are effective in treating amoebiasis.

You get infected when you swallow the parasite Entamoeba histolytica that causes amoebiasis. The parasite can spread when infected people don't dispose of their poo hygienically or don't wash their hands properly after going to the toilet.

You can ingest the parasite when you:

• eat contaminated raw fruit and vegetables
• drink contaminated water
• engage in unprotected sexual activity (oral–anal sex).

The parasite can survive for weeks, or even months, in soil, fertiliser, or water that's contaminated with infected faeces (poo). 

Note: Most people who become infected don't have symptoms, but the parasite is still present in their poo.

People who have amoebiasis have recently travelled to areas where amoebiasis is common. This is mostly countries with poor sanitation, such as in Central and South America, Africa, and Asia.

Most people who have the parasite don't have symptoms, or have mild symptoms such:

• watery, runny poo (diarrhoea)
• stomach cramps
• fever (high temperature).

Symptoms usually develop within 2 to 4 weeks but can show up later. In rare cases, people can develop severe symptoms.

Severe symptoms of amoebiasis

Amoebic dysentery

This is severe inflammation of the gut causing ulceration of the intestinal lining. Symptoms include severe diarrhoea with blood and mucus in your poo, loss of appetite, weight loss, or bleeding from the rectum with no diarrhoea. Symptoms can last for several weeks.

Amoebic liver abscess

This happens when the parasite passes through the intestinal wall, enters your bloodstream, and moves to your liver where it forms an abscess. The abscess is filled with pus. It can develop some time after the initial infection – months or years. Symptoms include fever and abdominal (tummy) pain or discomfort and tenderness. You may also notice that the skin and the whites of your eyes become yellow (jaundiced) and your liver may also become enlarged (a doctor may be able to tell this when they examine your abdomen).

Rarely, the parasite has spread to other parts of the body, including the lungs and brain.

Amoebiasis is diagnosed by testing for the presence of the parasite in your poo. If you develop gastro after returning home from overseas, contact your healthcare provider, so they can arrange for a test.

• You will need to provide a poo sample. It will be sent to the laboratory and examined under a microscope.
• You may be asked for several samples from different days. This is because E. histolytica isn't always found in every sample.
• Diagnosing amoebiasis can be very difficult because other parasites and cells can look very similar to E. histolytica under a microscope.

For the diagnosis of amoebic liver abscess, the parasite may be seen when pus from the liver abscess is examined under a microscope. To collect the pus, a needle is passed through your skin into the abscess. An ultrasound scan is usually used to guide the person performing the procedure.

If the results of your poo tests show that you have the parasite, your doctor will prescribe medicines to kill the parasite. This is important even for people who don't have symptoms, to reduce the risk of spread. Examples of medicines include metronidazole, ornidazole and paromomycin.

People with amoebiasis must not attend school, child care services or work until the diarrhoea has stopped.

• You'll need to take time off work until the symptoms stop.
• If you're a food handler or healthcare worker, you will need to talk to your healthcare provider about when you can return to work. You may need another poo test to ensure the infection has cleared first. 

There is no vaccine to prevent amoebiasis.

To avoid getting amoebiasis:

• Wash your hands thoroughly with soap and hot running water for at least 15 seconds after using the toilet or changing a nappy and before preparing food.
• Wash raw fruit and vegetables before eating.
• Only drink water that's treated and known to be safe – if you're not sure if the water is safe, boil it first.

If you're travelling overseas (especially to less developed countries)

• Be careful around the food and water you consume. Avoid uncooked foods. Avoid fruit and vegetables unless you're able to peel them yourself and then wash your hands.
• Drink only packaged drinks, boiled water or chlorinated and filtered water. Avoid drinks containing ice.