Diphyllobothriasis

Antibodies

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.

Also known as: Fish tapeworm infection

Definition

Diphyllobothriasis is an infection from a fish tapeworm.

Causes, incidence, and risk factors

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 tapeworm cysts.

The infection is seen in many areas where humans eat uncooked or undercooked fish from rivers or lakes. Diphyllobothriasis is seen in Eastern Europe, North and South America, African countries in which freshwater fish are eaten, and in some Asian countries.

After a person has eaten infected fish, the larva begin to grow in the intestine. They 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. Occasionally, parts of the worm may also be passed in the stool.

Fish tapeworm infection may lead to vitamin B12 deficiency and megaloblastic anemia.

Symptoms

Most people who are infected have no symptoms. Symptoms may include:

  • Abdominal discomfort or pain
  • Nausea, vomiting, or diarrhea
  • Loss of appetite and weight loss

Signs and tests

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

Tests may include:

Treatment

You will receive medicines to fight the parasites. Medicines are taken by mouth, usually in a single dose.

The drug of choice for tapeworm infections is niclosamide. Praziquantel and albendazole can also be used. You may need vitamin B12 injections or supplements to treat megaloblastic anemia that can occur with this infection.

Expectations (prognosis)

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

Complications

  • Megaloblastic anemia
  • Intestinal blockage

Calling your health care provider

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

Prevention

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.

References

King CH. Cestode infections. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 375.

See also:

  • Disease

    Pernicious anemia

    Megaloblastic anemia - view of red blood cells

    Pernicious anemia is a decrease in red blood cells that occurs when the body cannot properly absorb from the gastrointestinal tract. Vitamin B12 is necessary for the proper development of red blood cells. Pernicious anemia is a type of . See also:

  • Disease

    Megaloblastic anemia

    Megaloblastic anemia - view of red blood cells

    Megaloblastic anemia is a blood disorder in which there is with larger-than-normal red blood cells. Anemia is a condition in which the body does not have enough healthy red blood cells. Red blood cells provide oxygen to body tissues.

  • Nutrition

    Vitamin B12

    Vitamin B12 benefits

    Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses these vitamins, leftover amounts leave the body through the urine. The body can store vitamin B12 for years in the liver.

Review date:
August 28, 2009
Reviewed by:
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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