Diphyllobothriasis
Key points
- Diphyllobothriasis is an infection caused by a fish tapeworm.
- The fish tapeworm, scientifically named Diphyllobothrium latum, represents one of the giant tapeworm species.
- The vast majority of infected individuals have no symptoms.
- Treatment Niclosamide or praziquantel are given in a single dose to treat the tapeworm infection.
Alternative names
Fish tapeworm infection
Definition
Diphyllobothriasis is an infection caused by a fish tapeworm.
Causes, incidence, and risk factors
The fish tapeworm, scientifically named Diphyllobothrium latum, represents one of the giant tapeworm species. Humans become infected when they eat raw or undercooked fish that contain tape worm larvae (sparganum).
The infection is seen in many areas where humans consume 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 of infected fish, the larva begin to grow in the intestine. The adult worm, which is segmented, may attain a length of 30 feet. Eggs are formed in each segment (proglottid) of the worm and are passed in the stool. Occasionally, a string of proglottids may be passed in the stool.
Fish tapeworm infection may lead to Vitamin B12 deficiency and the subsequent development of megaloblastic anemia (pernicious anemia).
Symptoms
The vast majority of infected individuals have no symptoms. Symptoms seen with heavy infections may include:
- vague abdominal discomfort
- nausea, vomiting, or diarrhea
- loss of appetite and weight loss
- abdominal pain due to intestinal blockage by worms
- individuals with vitamin B-12 deficiency may suffer:
o fatigue due to anemia
o numbness and tingling in their limbs
o confusion or dementia
Signs and tests
- infected individuals sometimes pass visible segments of worm (proglottids) in stool
- stool smear for tapeworm eggs
- CBC may reveal anemia with large red blood cells (macrocytic anemia)
Treatment
Niclosamide or praziquantel are given in a single dose to treat the tapeworm infection. Vitamin B-12 injections or supplements may be needed for the treatment of megaloblastic anemia.
Expectations (prognosis)
Fish tapeworms can be eradicated with a single treatment dose. There are no lasting effects.
Complications
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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