Saturday, August 25, 2012

Answer to Case 222

Answer:  Acanthocephaliasis (thorny-headed worm infection) due to Moniliformis moniformis

This was a challenging case, and I was very pleased to see how many people submitted the correct answer. 

The diagnosis of acanthocephaliasis can be made from recognizing the armed proboscis with recurved hooks protruding from the worm. 

Most cases of human canthocephaliasis are due to Macracanthorhynchus hirudinaceous and Moniliformis moniliformis, which can be differentiated by their eggs recovered in stool.  The eggs of M. hirudinaceous are thick-walled with a dark textured shell, whereas the eggs of M. moniliformis are thin-shelled and oval/elongate.  Some viewers commented that the eggs of M. moniliformis resemble those of Enterobius vermicularis, but are larger, more elongate, and don't have a flattened side like E. vermiculis.

Of note, M. moniliformis is transmitted by ingestion of arthropods such as beetles and cockroaches.  This explains why this infection is seen in young children, as well as in populations that eat arthropods for medicinal or dietary purposes.

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