Diphyllobothriasis (patient information)

Diphyllobothriasis is an infection with a parasite found in fish.

Most people who are infected have no symptoms. If symptoms do occur, they may include:

• Abdominal discomfort or pain
• Diarrhea
• Weakness
• Weight loss

The fish tapeworm (Diphyllobothrium latum), is the largest parasite that infects humans. Humans become infected when they eat raw or undercooked freshwater fish that contain fish tapeworm cysts. The infection is seen in many areas where humans eat uncooked or undercooked fish from rivers or lakes such as:

• Eastern Europe
• North and South America
• Scandinavia
• Some Asian countries

After a person has eaten infected fish, the larva begins to grow in the intestine. Larvae are fully grown in 3 – 6 weeks. The adult worm, which is segmented, may reach a length of 30 feet. Eggs are formed in each segment of the worm and are passed in the stool. Sometimes, parts of the worm may also be passed in the stool. Fish tapeworm infection may lead to vitamin B12 deficiency and megaloblastic anemia.

Diphyllobothrium infection generally occurs in the Northern Hemisphere (Europe, newly independent states of the Former Soviet Union, North America, Asia), but has been reported in Uganda and Chile. Fish infected with Diphyllobothrium larvae may be transported to and consumed in any area of the world.

Call your health care provider if:

• You have noticed a worm or segments of a worm in your stool
• Any family members have symptoms of pernicious anemia

People who are infected sometimes pass segments of worm in their stools. These segments can be seen in the stool. Tests may include:

• Complete blood count, including differential
• Stool examination for eggs and parasites

You will receive medicines to fight the parasites. You take these medicines by mouth, usually in a single dose. The drug of choice for tapeworm infections is praziquantel. Niclosamide can also be used. You may need vitamin B12 injections or supplements to treat megaloblastic anemia that can occur with this infection.

Directions to Hospitals Treating Diphyllobothriasis

Fish tapeworms can be removed with a single treatment dose. There are no lasting effects.

• Megaloblastic anemia
• Intestinal obstruction

Avoiding raw freshwater fish and cooking fish enough (to more than 140 degrees F for 5 minutes) will prevent infection with the fish tapeworm. Freezing fish to -4 degrees F for 24 hours also kills fish tapeworm eggs.

http://www.nlm.nih.gov/medlineplus/ency/article/001375.htm