The Therapeutic Efficacy of Azithromycin and Nitazoxanide in the Acute Pig Model of Cryptosporidium Hominis

Recent reports highlighting the global significance of cryptosporidiosis among children, have renewed efforts to develop control measures. We have optimized the gnotobiotic piglet model of acute diarrhea to evaluate azithromycin (AZR), nitazoxanide (NTZ), or treatment with both against Cryptosporidium hominis, the species responsible for most human cases. Piglets, animals reproducibly clinically susceptible to C. hominis, when inoculated with 106 oocysts, developed acute diarrhea with oocyst excretion in feces within 3 days. Ten day-treatment with recommended doses for children, commencing at onset of diarrhea, showed that treatment with AZR or NTZ relieved symptoms early in the treatment compared with untreated animals. Piglets treated with AZR exhibited no reduction of oocyst excretion whereas treatment with NTZ significantly reduced oocyst shedding early, increasing however after 5 days. While treatment with AZR+NTZ led to considerable symptomatic improvement, it had a modest effect on reducing mucosal injury, and did not completely eliminate oocyst excretion. Doubling the dose of AZR and/or NTZ did not improve the clinical outcome, confirming clinical observations that NTZ is only partially effective in reducing duration of diarrhea in children. This investigation confirms the gnotobiotic piglet as a useful tool for drug evaluation for the treatment of cryptosporidiosis in children.