Definition

Tapeworms are large, flat parasitic worms that live in the intestinal tracts of some animals. They are passed to humans who consume foods or water contaminated with tapeworm eggs or larvae.

Six types of tapeworms are known to infect humans, usually identified by their source of infestation: beef, pork, fish, dog, rodent, and dwarf (named because it is small).

There are often no symptoms as tapeworms grow in humans. In some cases, untreated tapeworm infection can be life-threatening or lead to permanent tissue damage. But, tapeworm infections confined to the intestines can easily be treated with medication.

Digestive Pathway Tapeworms enter the human body with contaminated food or water and remain in the intestines. Copyright © Nucleus Medical Media, Inc.

Causes

Tapeworm infection in people usually results from eating undercooked foods from infected animals. Pigs or cattle, for example, become infected when grazing in pastures or drinking contaminated water. People can also become infected by eating contaminated fish that is raw or undercooked.

The parasites mature in the animal’s intestines to pea-shaped larvae. They spread to the animal's blood and muscles. They are then transmitted to people who eat the contaminated food. This method is more common with beef or fish.

In addition, tapeworms can also be passed from hand-to-mouth contact if you touch a contaminated surface and then touch your mouth. This method is more common with pork.

Risk Factors    TOP

The following factors increase your chances of developing tapeworm infection. If you have any of these risk factors, tell your doctor:

• Eating raw or undercooked pork, beef, or fish
• Poor hygiene—Not washing your hands can increase the risk of transferring tapeworm parasite from hand-to-mouth.
• Exposure to cattle or pigs, particularly in areas where human and animal feces are not properly disposed
• Travel to underdeveloped countries with poor sanitary conditions.

Symptoms    TOP

In some cases, tapeworm infection may not cause any symptoms. If symptoms do occur, they may include:

• Nausea
• Weakness
• Diarrhea
• Abdominal pain
• Hunger or loss of appetite
• Fatigue
• Weight loss
• Seizures in rare cases (pork tapeworm)

If you have any of these symptoms, see your doctor.

Diagnosis    TOP

You may be able to self-diagnose tapeworm infection by checking your stool for signs of tapeworms. But more likely, if you suspect infection, see your doctor, who will ask about your symptoms and medical history, and perform a physical exam. Tests may include the following:

• A stool sample that will be sent to a laboratory for analysis. Sometimes, several samples are needed over a designated period, since tapeworm eggs and segments may be released irregularly in human stool.
• A blood test to indicate the presence of antibodies produced to fight tapeworm infection
• A CT or MRI scan—a type of x-ray that uses computers (CT) and magnetic waves (MRI) to make pictures of structures inside the body. These scans may be needed for serious cases in which the parasite might have infected other areas of your body beside the digestive tract.

Treatment    TOP

Tapeworm infection is treated with oral medication. Commonly used drugs include:

• Praziquantel (Biltricide)
• Albendazole (Albenza)

These medications work by dissolving or attacking the adult tapeworm, but may not target eggs. Proper hygiene is essential to avoid re-infection; always wash your hands before eating or after going to the bathroom.

Your doctor will check stool samples at one and three months after you've finished taking your medication. The success rate is greater than 95% in patients who receive appropriate treatment.

Prevention    TOP

To help reduce your chances of getting a tapeworm infection, take the following steps:

• Wash your hands with soap and hot water before eating or handling food
• Wash your hands after using the toilet.
• Freeze meat for four days or longer to kill the type of tapeworm that infects pork.
• Thoroughly cook meat at temperatures of at least 150°F (65°C). Avoid eating raw or undercooked food.
• When traveling in undeveloped countries, wash and cook all fruits and vegetables with safe water before eating.
• Get prompt treatment for pets infected with tapeworm.