Severe Isospora (Cystoisospora) belli Diarrhea Preceding the Diagnosis of Human T-Cell-Leukemia-Virus-1-Associated T-Cell Lymphoma

Isospora (Cystoisospora) belli diarrhea can sometimes be fulminant in immunocompromised patients. It is endemic in tropical and subtropical areas, and sporadic episodes have been reported in nonendemic areas in nursing homes, day-care centers, and psychiatric institutions. We describe isosporiasis in an HIV-negative Sudanese-American female who presented with a debilitating diarrheal illness and profound weight loss. Isospora belli was detected in her stool by modified acid-fast staining. Serologic testing was negative for HIV but positive for HTLV-1 infection. Treatment with TMP-SMZ led to improvement in her diarrhea which recurred after stopping antibiotics. Subsequently, she developed generalized lymphadenopathy which was diagnosed as ATLL on immunohistochemical staining. Chemotherapy was initiated, but her condition continued to worsen due to persistent diarrhea and resulting profound electrolyte abnormalities. The patient opted for comfort measures and died a few weeks later at a nursing facility. This case emphasizes that the detection of I. belli should trigger testing for HIV, HTLV-1, and other causes of immunocompromise. We suggest that treatment with TMP-SMZ should be initiated and continued for a prolonged period of time in immunocompromised patients with I. belli diarrhea. 1. Introduction Isospora belli is a coccidian, unicellular protozoan parasite that resides in the gastrointestinal tract. It usually causes nonbloody diarrhea in tropical and subtropical climates [1, 2]. In developed countries, it is found in recent immigrants, travelers returning from endemic regions, and patients with AIDS [3]. The disease course is mild and usually transient in immunocompetent hosts. In immunocompromised individuals, the disease can vary in severity from a chronic intermittent illness to severe life-threatening diarrheal illness. We describe severe isosporiasis in a non-HIV patient with human T-cell-leukemia-virus-1- (HTLV-1-) associated T-cell lymphoma living in a nontropical climate. 2. Case A 44-year-old Sudanese-American female was transferred to our hospital from another facility with the chief complaint of chronic diarrhea. She had emigrated from Sudan to the United States ten years previously and had never revisited her home country. She was relatively healthy until nine months prior to admission when she experienced the insidious onset of cramping epigastric pain and diarrhea. The diarrhea was in large volume, with 10–20 bowel movements daily. Her stools were watery, with very little formed stool and no blood or mucus. Her condition led to