Abstract

Gastric cryptosporidiosis caused by Cryptosporidium serpentis has impacted the conservation efforts for the imperiled eastern indigo snake (EIS, Drymarchon couperi). Multiple treatments, including paromomycin, nitazoxanide-azithromycin-rifabutin, clofazimine, curcumin, and hydrogen peroxide gavage, have been investigated and proved ineffective in eliminating the parasite, necessitating further investigation. A novel piperazine-based compound, MMV665917, has been shown to be more effective than paromomycin, nitazoxanide, and clofazimine in treating cryptosporidiosis in mammals. With these promising results, MMV665917 was selected to investigate as a treatment of gastric cryptosporidiosis in EIS. Twelve EIS naturally infected with C. serpentis were randomly divided into two groups of six: Group A and Group B. Group A received 22 mg/kg MMV665917 daily for 7 days, and Group B received a placebo daily for 7 days. All EIS tolerated the treatment with no adverse effects appreciated. Success was evaluated by C. serpentis–specific probe hybridization qPCR analysis of gastric lavage performed 1, 2, and 3 months following the treatment. Infections persisted following treatment, and there was no statistical difference in qPCR cycle threshold values between the groups or within the groups for the 3 months following treatment (F = 0.92, P = 0.525). These findings show that MMV665917 dosed at 22 mg/kg daily for 7 days is ineffective in eliminating C. serpentis in EIS and alternative MMV665917 dosing or formulations should be investigated in reptiles.