Context.— Cryptosporidium parvum infection, a common
cause of diarrhea in persons infected with the human immunodeficiency virus
(HIV), is difficult to treat or prevent.
Objective.— To evaluate relative rates of cryptosporidiosis in HIV-infected patients
who were either receiving or not receiving chemoprophylaxis or treatment for Mycobacterium avium complex.
Design.— Analysis of prospectively collected data from HIV-infected patients'
visits to their physicians since 1992.
Setting.— Ten (8 private, 2 publicly funded) HIV clinics in 9 US cities.
Patients.— A total of 1019 HIV-infected patients with CD4+ cell counts
less than 0.075×109/L.
Main Outcome Measures.— Incidence of clinical cryptosporidiosis during treatment with clarithromycin,
rifabutin, and azithromycin.
Results.— Five of the 312 patients reportedly taking clarithromycin developed
cryptosporidiosis vs 30 of the 707 patients not taking clarithromycin (relative
hazard [RH], 0.25 [95% confidence interval (CI), 0.10-0.67]; P =.004).Two of the 214 patients taking rifabutin developed cryptosporidiosis
vs 33 of the 805 not taking rifabutin (RH, 0.15 [95% CI, 0.04-0.62]; P=.01). Prophylactic efficacy of either drug was 75% or
greater. No protective effect was seen in the 54 patients reportedly taking
azithromycin (RH, 1.48 [95% CI, 0.44-5.04]; P=.46).
Conclusions.— Clarithromycin and rifabutin were highly protective against development
of cryptosporidiosis in immune-suppressed HIV-infected persons in this analysis;
further study is warranted.