Parasites are organisms that live in your intestinal tract and feed off the nutrients you ingest. Often, they are acquired by ingesting contaminated water or food that hasn't been properly cleaned. In some cases, parasites can enter your bloodstream through the intestinal wall and infest major organs, such as the liver or brain. Fortunately, parasites are highly curable, with some cases requiring only one treatment.

Parasites affect 1 billion people worldwide. One of the most common parasites is the tapeworm, which can grow up to 50 feet long and can live inside the body for 20 years. Tapeworm symptoms are very non-specific, so if you experience ongoing nausea, abdominal pain or diarrhea, be sure to consult your doctor.

Gastroenterologist Dr. Susan Edelstein reveals some of the common parasites that use the human body as a host.
Common causes
You can become infected with parasites if you ingest their eggs in contaminated water supplies or in food, such as rare or raw meats.

Parasites in raw fish are killed when the fish is stored at 10 degrees Fahrenheit for five days, but not all restaurants adhere to those regulations.

Americans often contract parasites while traveling abroad. Gastroenterologist Dr. Su Sachar recommends steering clear of all tap water, including ice, as well as eating only peeled fruits when visiting another country.

Common symptoms:
Abdominal pain

Learn more about the typical symptoms of a parasitic infection and how to diagnose the condition.

Treatment options
The reaction to most intestinal parasites is not life-threatening and will last only two to four days, but some patients could experience months of irritable bowels, gastroenterologist Dr. Jeffrey Sherman says.

Stomach-turning parasites How long a tapeworm can grow in your body
Treating diarrhea