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Updated February 10, 2012

Case 6: A 37-Year-Old Migrant Worker with Diarrhea

Authors: Cedric W. Spak, MD David H. Spach, MD

A 37-year-old HIV-infected Mexican male presents with crampy abdominal pain and copious diarrhea for about one week. He is a migrant worker in the area and was recently diagnosed with HIV infection; initial laboratory studies showed a CD4 count of 19 cells/mm3 and a HIV RNA level of 67,000 copies/mL. He denies fever, chills, gastrointestinal bleeding, or vomiting. He has not started antiretroviral therapy, as he continues to drink alcohol heavily. He is taking no medications. The physical examination is notable for resting tachycardia, orthostatic changes, a temperature of 38.6°C, and diffuse abdominal tenderness (without signs of peritoneal irritation). Initial stool studies are negative for leukocytes or occult blood. An examination of a stool sample using a modified acid-fast smear on the stool sample reveals an abnormal finding that may explain the cause of his diarrhea (Figure 1).

Based on the patient’s clinical presentation and the findings of the stool sample tests, which of the following statements is most likely TRUE?

A The clinical manifestations and the modified acid-fast smear of the stool sample are consistent with a diagnosis of cystoisosporiasis. Treatment should be initiated with trimethoprim-sulfamethoxazole (Bactrim, Septra).
B The patient most likely has giardiasis.  Treatment should be initiated with metronidazole (Flagyl) or tinidazole (Tindamax).
C The clinical manifestations and stool analysis are most consistent with intestinal tuberculosis. An intestinal wall biopsy should be performed to make a definitive diagnosis.
D The clinical manifestations and the stool findings are most consistent with cryptosporidiosis. Treatment should be initiated with paromomycin (Humatin) or nitazoxanide (Alinia).

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    Figure 1. Modified Acid-fast Smear of Stool Sample

    Slide courtesy of Carolyn Wallis, Harborview Medical Center Microbiology Laboratory.

    Figure 1