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Diphyllobothrium Latum

Introduction

Diphyllobothrium latum (or fish tapeworm) has a complex cycle of infection. If sewage that is contaminated with eggs from humans who carry the fish tape worm gets ingested by fish in a fresh water lake, the fish get infected with larvae that hatched out of the eggs in the water.

The exact cycle is even more complicated, as the larvae first infect the plankton, which in turn is ingested by the fish (see life cyclethanks to www.rcn.com for this image).

The meat of the infected fish is full of the cysticerci, which is the strorage form of the tapeworm. When raw fish (such as infested sushi) is consumed by humans, these transform into fish tape worms in the intestinal wall of the human host within about 1 month. One fish tapeworm produces 1 million eggs per day in the human gut.

Signs and symptoms

As the fish tapeworm is very small compared to other tapeworms, it usually is asymptomatic. However, with its hyperactive metabolism to support the enormous egg production, it uses up all of the dietary vitamin B-12 of the human host. This leads to pernicious anemia in about 1% of affected patients.

Diagnostic tests

The characteristic eggs of the fish tapeworm can easily be detected from stool samples or clear self-adhesive tape samples from skin around the anal area.

Diphyllobothrium Latum (Fish Tapeworm Transmitted By Raw Fish)

Diphyllobothrium Latum (Fish Tapeworm Transmitted By Raw Fish)

Treatment

A single oral dose of praziquantel (brand name: Biltricide) is the treatment of choice. Pernicious anemia, if present, is treated with an intramuscular dosage of Vitamin B-12.

 

References:

1. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 161.

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5. JR Zunt and CM Marra  Neurol Clinics Vol.17, No.4,1999: 675-689.

6. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse   Station, N.J., 1999. Chapter 162.

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8. HW Cho: Vaccine 1999 Jun 4; 17(20-21): 2569-2575.

9. DO Freedman et al. Med Clinics N. Amer. Vol.83, No 4 (July 1999):     865-883.

10. SP Fisher-Hoch et al. J Virol 2000 Aug; 74(15): 6777-6783.

11. Mandell: Principles and Practice of Infectious Diseases, 5th ed., ©   2000 Churchill Livingstone, Inc.

12. Goldman: Cecil Textbook of Medicine, 21st ed., Copyright © 2000   W. B. Saunders Company

13. PE Sax: Infect DisClinics of N America Vol.15, No 2 (June 2001):   433-455.

14. David Heymann, MD, Editor: Control of Communicable Diseases Manual, 18th Edition, 2004, American Public Health Association.

Last modified: October 1, 2014

Disclaimer
This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.