Reviewed August 2017
What is amebiasis?
Amebiasis is caused by the parasite Entamoeba histolytica (E. histolytica), a tiny waterborne organism that is too small to be seen by the naked eye. Illness caused by this parasite occurs around the world, but in Canada, it is most common in travellers returning from a country with poor sanitation or unclean water.
How is amebiasis spread?
People get infected with the parasite by eating, drinking or putting something into their mouth that is contaminated with the stool of an infected person. Travellers to, and people living in, places with poor sanitation are at a higher risk of acquiring this infection. It is also spread by oral-anal contact during sex with someone who is infected. Animals are not involved in the spread of this parasite.
What are the symptoms of amebiasis infection?
Some people can be infected and not have any symptoms. About 10% to 20% of people who become infected with E. histolytica will have the following symptoms:
- Diarrhea (which occasionally can be mixed with blood)
- Abdominal cramps and pains
- Feeling unwell
Amebiasis is more severe in the very young, older individuals and those with weakened immune systems.
How soon after exposure to the parasite do symptoms usually begin?
Symptoms usually begin 2 to 4 weeks after exposure to the parasite, but it can be anywhere from days to months.
How do I know that I have amebiasis?
The signs and symptoms of amebiasis are similar to other stomach infections. Amebiasis can be confirmed through lab testing of stool samples. Multiple stool samples may be required to detect the parasite.
Are there related infections that might resemble amebiasis?
Yes. If you have been told that you are infected with E. histolytica but you are feeling fine, you might be infected with a related parasite called Entamoeba dispar (E. dispar) that does not cause illness. Another stool specimen may be requested (using a slightly different method of testing) to determine the difference between these two parasites. For uncomplicated illness that might be due to E. histolytica, doctors often just treat you with antibiotics without doing the extra test.
How is amebiasis infection treated?
Amebiasis is treated with antibiotics that are prescribed by your healthcare provider. It is important to drink extra fluids if you have diarrhea to prevent dehydration.
What are the possible complications of amebiasis infection?
In a small number of people the parasite can invade other parts of the body such as the liver (most commonly), lungs, heart and brain and damage these organs. Rarely, a more severe form called amebic dysentery can occur with symptoms of fever, severe stomach pain and bloody diarrhea that can result in death.
Can I still go school or work if I am infected?
Yes. Most individuals with amebiasis can continue with normal activities if they are well enough, but everyone is reminded that it is best to stay home when you are ill to reduce the risk of passing this infection to others. It is important that food handlers, those who provide healthcare services, those who work or attend a childcare centre and those who come into contact with water as part of their job (e.g., swimming pools, hot tubs or water parks) stay home and away from work or daycare until at least 24 hours after symptoms have gone away.
What can be done to prevent the spread of amebiasis infection?
- Thorough hand washing is the best prevention. Since the parasite is passed in stool, the single most important prevention activity is careful hand washing after using the washroom, handling diapers, before and after preparing food and before eating.
- Clean and sanitize diaper changing areas after each use.
- Do not prepare food for others if you have diarrhea.
- Avoid contact with stool during sex.
- When travelling:
- Drink water from a safe supply, or boil for at least one minute.
- Avoid ice cubes as they may carry the parasite.
- Avoid eating raw shellfish harvested from unknown sources.
- Peel fruits and vegetables, or wash with bottled water before eating.
If I am travelling to a place without clean water what can I drink to avoid getting amebiasis?
- Bottled water
- Carbonated beverages or water in sealed bottles or cans
- Water boiled for at least one minute or passed through a filter that eliminates the parasite. For more information about making water safe to drink go to http://www.cdc.gov/healthywater/drinking/travel/index.html
What is the role of Toronto Public Health in investigating amebiasis?
Amebiasis is a reportable communicable disease. Individuals living in Ontario who test positive for amebiasis must be reported to their local health department by either the lab or their health care provider. Toronto residents infected with amebiasis will be contacted by Toronto Public Health to get additional information to determine the source of the infection. This information can be helpful in ensuring that contaminated food or water does not cause illness to other people.
Where can I get more information about amebiasis?
Call Toronto Public Health at 416-338-7600 (TTY at 416-392-0658) or speak to your healthcare provider.