Amebiasis

Amebiasis is an infection of the intestine caused by a tiny parasite called Entamoeba histolytica. The parasite is found worldwide, but the risk of infection is highest where sanitary conditions are poor, and food and water become contaminated with human feces. There are several types of Entamoeba parasites, but species other than Entamoeba histolytica only rarely cause illness.

The parasite is spread through the feces (stool) of an infected person (who may or may not show illness), either indirectly by eating or drinking contaminated food or water, or by direct person-to-person contact. Direct contact may occur, for example, through poor hand washing or through sexual practices that allow contact with an infected person’s feces. It may also be possible to become infected by swimming in recreational waters that are contaminated with the parasite and swallowing even small amounts of water.

Symptoms usually start within 2 to 4 weeks of contact with the parasite, but this varies a great deal and can be shorter or very much longer. Most people have very mild symptoms or no symptoms at all. Symptoms may include loose or watery stool (sometimes bloody), tiredness, stomach cramps, painful straining when defecating, fever, weight loss, nausea and loss of appetite. Severe, bloody diarrhea, called amebic dysentery, can occur if the parasite enters the wall of the intestine. Amebic abscesses of the liver can occur. Serious illness is more likely to occur in people who have weakened immune systems, young children, pregnant women, and the elderly than those with a healthy immune system.

Treatment with medication is recommended for amebiasis and must be prescribed by a health care provider. If symptoms continue after treatment, it is important to see a health care provider as additional treatment may be needed.

Generally, people can return to work when they feel well. It is important that food handlers, those who provide health care services, and those who work at or attend a child care centre stay home and away from work or daycare until at least 24 hours after their symptoms stop or for 48 hours after completion of treatment. It is important not to swim in recreational waters, especially public pools and splash pads, until 2 weeks after symptoms have gone away.

To prevent becoming ill with amebiasis:

• Avoid local water when travelling to countries where the water supply is uncertain; instead use only sealed bottled water or treated (chemically disinfected or boiled) water for drinking, brushing teeth, preparing foods, making ice and cooking.
• Beware of raw foods washed in local water when travelling; eat only cooked food and fruit that can be peeled after it has been washed with water from a safe source.
• Avoid swallowing recreational water (in lakes, rivers, pools, etc.) while swimming
• Always wash hands well with soap and water for at least 15 seconds before and after preparing food, before eating, after using the toilet, after changing diapers, after handling pets or their feces, and any time hands may be dirty.
• Wash raw fruits and vegetables well with clean running water before eating. To prevent the fruit inside from becoming contaminated when cut or peeled, before peeling, scrub rough fruit like melons and oranges with a brush.
• Wait to resume sexual activity until you no longer have diarrhea. You may continue to have bacteria in your stool for a few weeks after you recover, so wash your body (genitals, anus, and hands especially) before and after sexual activity.
• Avoid preparing foods or drinks for others if you have diarrhea.

OPH must be notified by health care providers and laboratories when a person is ill with amebiasis. If the lab reports Entamoeba histolytica, OPH conducts an investigation to potentially determine the cause or source of the infection, provide education to the person with amebiasis and their close contacts, and follows up with the person’s health care provider, as needed. If a common source of illness is identified, OPH will provide follow-up investigation.