Reviewed: August 2017
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.
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.
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:
Amebiasis is more severe in the very young, older individuals and those with weakened immune systems.
Symptoms usually begin 2 to 4 weeks after exposure to the parasite, but it can be anywhere from days to months.
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.
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.
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.
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.
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.
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.
Call Toronto Public Health at 416-338-7600 (TTY at 416-392-0658) or speak to your healthcare provider.