Evaluation of the Drug Combination Nitazoxanide, Azithromycin, and Rifabutin as a Treatment for Cryptosporidium serpentis Infection in Eastern Indigo Snakes (Drymarchon couperi)

Abstract

Cryptosporidium serpentis is a common parasitic disease in captive snakes that is associated with substantial morbidity and mortality. The purpose of this study was to evaluate a new drug regimen for treating C. serpentis in eastern indigo snakes (Drymarchon couperi) (EIS). Twenty-four EIS naturally infected with C. serpentis were randomly divided into two groups. The first received 20 mg/kg nitazoxanide, 10 mg/kg azithromycin, and 5 mg/kg rifabutin twice weekly in a food item for 6 weeks, the second received no treatment. Cloacal swabs were collected every 2 months for 6 months to measure C. serpentis shedding by qPCR. Snakes that were qPCR negative after 6 months were immunosuppressed with a single dose of 4 mg/kg dexamethasone sodium-phosphate SC. These snakes were then screened by qPCR for an additional 6 months. Snakes that were qPCR negative after 1 year of sampling were re-evaluated for C. serpentis via gastric biopsy for histological and qPCR analyses. Only two (2/12; 16.7%, 95% CI: 0.1-37.8%) from each group were qPCR negative prior to immunosuppression. The snakes in the treatment group had a decrease in the amount of C. serpentis DNA shedding following treatment (P = 0.025) where the control animals did not (P = 0.232). Only one (1/12; 8.3%, 95% CI: 0.1-23.9) snake in each group was negative 6 months after immunosuppression. These findings suggest that 20 mg/kg nitazoxanide, 10 mg/kg azithromycin, and 5 mg/kg rifabutin twice weekly for 6 weeks in a food item is ineffective in eliminating C. serpentis in naturally infected EIS.