Tapeworm is a family of parasitic worms that most commonly infect people after they ingest contaminated water, pork, beef or freshwater fish.

Infection with tapeworm usually causes no symptoms. So, most infected people don’t even know they have it.

When symptoms do occur, they typically include:

• Diarrhea
• Abdominal pain or cramping
• Nausea or loss of appetite
• Fatigue
• Weight loss

More advanced infections may develop when newly hatched larvae migrate from the intestines into other areas, such as the liver or brain.

These infections may cause other symptoms, including:

• Fever
• Seizures, headaches or visual problems
• Lumps under the skin

The disease can be prevented by careful personal and food hygiene. This includes washing your hands well prior to meals, washing foods well and washing up well after going to the bathroom. Don’t eat undercooked or raw meats or fish, especially if you are in a place where tapeworm is common (as is true in many underdeveloped countries).

While oral medications can cure tapeworm, advanced infections in organs other than the digestive tract may be difficult to eliminate. For example, some types of tapeworms can cause large cysts in the liver that may require surgery to remove.

If you’re concerned that you have tapeworm, see your doctor. He or she can test the stool, check blood tests or do other tests to determine whether you have this type of infection.