Amebiasis

What is amebiasis?

Amebiasis is an intestinal infection 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 only Entamoeba histolytica is known to cause illness.

How is amebiasis spread?

The parasite is spread through the feces (stool) of an infected person, 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 anal-oral sexual contact where contact with feces may occur. It may also be possible to become infected by swimming in recreational waters that are contaminated with the parasite. People who have a weakened immune system, because of disease or medication, young children, pregnant women, and the elderly are more at risk of infection than those with a healthy immune system.

What are the symptoms of amebiasis?

Symptoms usually start within 2 to 4 weeks of exposure to the parasite, but this varies a great deal and can be 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, fever, weight loss, nausea and loss of appetite. Severe, bloody diarrhea, called acute dysentery, can occur if the parasite enters the wall of the intestine. Serious illness is more likely to occur in people who have weakened immune systems.

What is the treatment for amebiasis?

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. With appropriate treatment, the illness usually lasts for 2 to 3 weeks.

Are there any restrictions or special considerations for people ill with amebiasis?

Generally, people can return to work when they feel well, but 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. It is important not to swim in recreational waters, especially public pools and splash pads, until 2 weeks after symptoms have gone away.   

How can I protect myself against amebiasis?

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 anytime 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, scrub rough fruit like melons and oranges with a brush first 
  • Avoid contact with feces (stool) during sexual activity
  • Avoid preparing foods or drinks for others if you have diarrhea
What is Ottawa Public Health's role?

Ottawa Public Health (OPH) must be notified by health care providers and laboratories when a person is infected with amebiasis. OPH conducts an investigation to potentially determine the cause or source of the infection, provide education to the infected person and their close contacts, and follows up with the infected person's health care provider, as needed. 

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