Some intestinal parasites (e.g. E. histolytica, Giardia) can cause symptoms such as loose foul-smelling stools, diarrhea, mucous in stools, abdominal cramps and gas. These symptoms may last for weeks and return several times a year. Other parasites are harmless and often don’t cause symptoms (e.g. E. hartmanni, E. coli). In North America and Europe, parasites rarely cause serious complications. If you are experiencing any of the above complaints, see your doctor.
You can get parasites the same way you get hepatitis A, from oral contact anywhere in the anal area. This includes contact with fingers which have been in the anus, and handling soiled condoms. Parasites can also be transmitted in food and water.
If you have parasites, you can prevent passing them on to others by washing your hands carefully after having bowel movements, cleaning the anal area before having sex, and being careful when handling soiled condoms. These precautions are especially important for food handlers and care givers. If you are HIV+ (or suspect you may be) avoid rimming, since certain parasites may weaken your immune system.
Your doctor sends stool samples to a lab for testing. If you have intestinal parasites, treatment will depend on the type of parasite found in your stool. Some doctors say that since parasites rarely cause complications, treatment should be given only if your symptoms are bothersome. The treatments themselves contain very potent chemicals that could be harmful if taken incorrectly.