Background: Cryptosporidiosis is a disease that causes diarrhoea lasting about one to two weeks, sometimes extending up to 2.5 months among the immunocompetent and becoming a more severe life-threatening illness among immunocompromised individuals. Cryptosporidium is a common cause of gastroenteritis. Cryptosporidiosis is common in HIV-infected individuals.
Objectives: The objective of the review was to assess the efficacy of interventions for the treatment and prevention of cryptosporidiosis among immunocompromised individuals.
Search strategy: We searched the following databases for randomised controlled trials up to August 2005: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, AIDSLINE, AIDSearch, EMBASE, CINAHL, Current Contents, Geobase, and the Environmental Sciences and Pollution Management.
Selection criteria: Randomised controlled trials that compared the use of any intervention to treat or prevent cryptosporidiosis in immunocompromised persons were included. The outcome measures for treatment studies included symptomatic diarrhoea and oocyst clearance.
Data collection and analysis: Two reviewers independently assessed the trials for quality of randomisation, blinding, withdrawals, and adequacy of allocation concealment. The relative risk for each intervention was calculated using a random effects model.
Main results: Seven trials involving 169 participants were included. There were 130 adults with AIDS enrolled in five studies. Evidence of significant heterogeneity was present. There was no evidence for a reduction in the duration or frequency of diarrhoea by nitazoxanide (RR 0.83 (95% CI 0.36-1.94)) and paramomycin (RR 0.74 (95% CI 0.42-1.31)) compared with placebo. Nitazoxanide led to a significant evidence of oocyst clearance compared with placebo among all children with a relative risk of 0.52 (95% CI 0.30-0.91). The effect was not significant for HIV-seropositive participants (RR 0.71 (95% CI 0.36-1.37)). HIV-seronegative participants on nitazoxanide had a significantly higher relative risk of achieving parasitological clearance of 0.26 (95% CI 0.09-0.80) based on a single study. The single study comparing spiramycin with placebo found no significant difference in reduction of the duration of hospitalisation (mean difference -0.40 days (95% CI -6.62-5.82)) or in mortality between the two arms of the trial (RR 0.43 (95% CI 0.04-4.35)). One study assessed the role of bovine dialyzable leukocyte extract, reporting a relative risk for decreased stool frequency of 0.19 (95% CI 0.03-1.19), while another compared bovine hyperimmune colostrum with placebo and found no evidence for improvement of stool volume (RR 3.00 (95% CI 0.61-14.86)) or in oocyst concentration per ml of stool (RR 0.27 (95% CI 0.02-3.74)). No studies were found that assessed prevention.
Authors' conclusions: This review confirms the absence of evidence for effective agents in the management of cryptosporidiosis. The results indicate that nitaxozanide reduces the load of parasites and may be useful in immunocompetent individuals. Due to the seriousness of the potential outcomes of cryptosporidiosis, the use of nitaxozanide should be considered in immunocompromised patients. The absence of effective therapy highlights the need to ensure that infection is avoided. Unfortunately, evidence for the effectiveness and cost-effectiveness of preventive interventions is also lacking.