An examination of Cryptosporidium parvum infection in neonate BALB/c mice and rats

Introduction and objective: Cryptosporidium parvum is an intracellular, extracytoplasmic, zoonotic, coccidian parasite that infects the microvillus regions of the digestive tract, and respiratory tract and causes lethal disease mainly among individuals suffering from immune deficiency and children. Suitable animal models are needed to identify different aspects of Cryptosporidium infection and the means of treating and preventing this infection.  This study was conducted to represent a simple and usable animal model for C. parvum so that it can be used in the drug-related studies.

Materials and methods: Forty neonatal BALB/c mice and forty neonatal rats as group I (case) were inoculated with 5×10⁵ oocysts. At the same time the animals in group II (control) received only sterile PBS solution. The intensity of infection was determined through the microscopic observation of the homogenized intestines of all the samples at 6, 9, 12, and 16 days of post infection.

Results: In mice and rats, the intensity of infection in group I (case) reached its peak on the 9^th day after infection, then it reduced gradually and on day 16 post infection, it showed its lowest point. Meanwhile the non-infected animals in group II (control) had no detectable oocysts.

Conclusion: As the intensity of infection in both models showed a similar pattern; and because of rat physiological similarity to humans and easier handling and manipulation during the procedure the rat model was considered experimentally preferable.

Significance and impact of the study: This study introduces an indigenous laboratory animal model which can be used in cryptosporidium-related investigations and in vivo oocysts reproduction and it has no precedence in Iran.