DDSEP® 8 Quick Quiz

December 2016 Quiz 1

Publish date: December 2, 2016

Q1: A 23-year-old HIV-positive Hispanic man presents to the clinic with acute diarrhea for 5 days. He recently returned from a month-long trip to Mexico. He describes sudden onset of watery diarrhea associated with nausea and headache. His physical examination is unremarkable except for dry skin and dry oral mucus membranes; laboratory investigations reveal mild leukocytosis with eosinophilia.

What is the most likely cause of his diarrhea?

Cryptosporidium

Cyclospora

Cystoisospora

Microsporidia

Q1: Answer: C

Cystoisospora belli (formerly known as Isospora belli) is a gastrointestinal protozoan. In patients with AIDS and other immunodeficiencies, it is an opportunistic pathogen that can cause watery diarrhea and weight loss. Infections are acquired by the ingestion of sporulated oocysts from food or water contaminated with human feces. In general, protozoal infections do not cause peripheral or tissue eosinophilia; however, Cystoisospora infection is an exception to this rule.

Diarrhea and peripheral eosinophilia in an immunocompromised individual should raise concern for Cystoisospora infection. The other protozoal infections listed can cause diarrhea, but do not cause eosinophilia.

Reference

1. Goodgame, R.W. Understanding intestinal spore-forming protozoa: Cryptosporidia, microsporidia, isospora, and cyclospora. Ann Intern Med. 1996;124:429-41.

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Clinical Challenges - December 2016