Parasitology Training Manual

Diphyllobothrium latum

• Abbreviation: Dl
• A cestode
• Egg size 55 - 75 microns
• Common name: Fish Tapeworm
• Man and other mammals are hosts.
• The typical egg is operculated with a knob like projection on the opposite end.
• The proglottids are broader than long with a rosette shaped ovary located centrally.
• Two intermediate hosts are required in the life cycle.

Click on the image below to enlarge.

D. latum Life Cycle

The adult worm resides in the small intestine laying upwards of 1,000,000 eggs daily. When egg laying is complete the proglottid degenerates. The eggs are released with the feces in fresh water and hatch to form a ciliated coracidium which is ingested by the copepod, Cyclops(see photo). In the gut of Cyclops a proceroid develops. Cyclops are a food source for many small fresh water fish. When the fish eats the infected cyclops the proceroid penetrates the intestinal wall, migrates to muscle tissue and forms a pleroceroid. When undercooked fish is ingested by man the scolex of the pleroceroid attaches itself to intestinal mucosa and matures into the adult worm.

Return To Helminth Introduction

The material on this site is owned by Scientific Image and Consulting
David M. Raymondo
MLT, CLS(m)
Professional Affiliation: Gamma-Dynacare Medical Laboratories, Ottawa, Ontario, Canada
Gamma-Dynacare is a Division of the Dynacare Health Group