The role of Microsporidia in the pathogenesis of HIV-related chronic diarrhea.

OBJECTIVE

To determine whether infection with Microsporidia leads to diarrhea in patients with human immunodeficiency virus (HIV) infection.

DESIGN

Case-control study.

SETTING

Primary care outpatient HIV clinic at a Veterans Affairs medical center.

PATIENTS

One hundred six HIV-infected men, 55 with and 51 without chronic diarrhea.

MEASUREMENTS

Each patient underwent upper endoscopy and flexible sigmoidoscopy to obtain duodenal, rectal, and sigmoid colonic biopsy specimens. At the time of endoscopy, a fresh stool was obtained for culture, ova and parasite assessment, and Cryptosporidium examination. Biopsy tissue was examined using electron microscopy to detect Microsporidia.

RESULTS

The microsporidian parasite Enterocytozoon bieneusi was detected in the duodenal biopsy specimens of 31 of 106 men (29%); 24 of 106 men (23%) had other enteric pathogens. No significant difference was observed in the occurrence of microsporidiosis in patients with (18 of 55 [33%]) and without (13 of 51 [25%]) chronic diarrhea (odds ratio, 1.42; 95% CI, 0.61 to 3.31). A similar nonsignificant difference was observed after controlling for CD4 count and other enteric pathogens (odds ratio, 1.66; 95% CI, 0.68 to 4.06). Among patients with microsporidiosis, no difference was observed in the intensity of infection (defined by the presence of few, moderate, or abundant organisms) among cases and controls (P > 0.2).

CONCLUSIONS

This is the first report to document the presence of E. bieneusi in HIV-positive patients without gastrointestinal symptoms. No significant difference was observed in the occurrence of E. bieneusi infection in HIV-infected patients with or without chronic diarrhea. Thus, the association between microsporidiosis and diarrhea, if one exists, may not be as strong as is currently believed.