Pathogen of the Week:

Gnathostoma hispidum

By Amber Hsiao | Wednesday, January 18, 2006

Think you're safe from eating uncooked fish or poultry? Next time you reach for that piece of fish or chicken, consider that it may contain Gnathostoma hispidum, a species of the more commonly known roundworm, or nematode.

The nematode goes through a cycle of infecting hosts before it transforms into the adult worm. The natural hosts of the parasite are domestic animals. When they defecate, the unembryonated eggs are passed through the feces.

These unembryonated eggs hatch in water and can result in first-stage larvae. This is when small crustaceans can ingest the parasite, resulting in second-stage larvae. When the Cyclops crustacean is ingested by a larger animal, third-stage larvae can develop.

Human gnathostomiasis is manifested when third-stage larvae are ingested, contained within uncooked fish or poultry. These worms are usually found in an arm or leg of the human, which must be surgically removed.

Symptoms of roundworm ingestion include painful, itchy swellings, a cough, blood in urine, and the worst-case scenario-meningitis with inflammation of the spinal cord.

But fret not—cases of human gnathostomiasis are rare in the United States. They are most often seen in cultures that value traditional food dishes, such as seviches in Ecuador.

There is a correlation between food preparation practices and contraction of the parasite. Gnathostoma larvae can be easily killed off at high cooking temperatures.

So, be cautious about how your prepare your food-you don't want to contract a case of human gnathostomiasis before your first big exam!

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PHOTO // Web Atlas of Medical Parasitology

Originally appeared in the Daily Californian, Science-Technology section. See the original article.