Individual subject meta-analysis of parameters for Cryptosporidium parvum shedding and diarrhoea in animal experimental models.

Cryptosporidium is a zoonotic protozoan parasite with public health importance worldwide. The objectives of this study were to (1) conduct a meta-analysis of published literature for oocyst shedding and diarrhoea outcomes, and (2) develop recommendations for standardization of experimental dose-response studies. Results showed that for the outcome of oocyst shedding in faeces, the covariates 'experimental species', 'immunosuppression', 'oocyst dose' and 'oocyst dose' × 'age' were all significant (P≤0.05). This study suggests that exposing mice, piglets, or ruminants, and using immunosuppressed experimental hosts, is more likely to result in oocyst shedding. For the outcome of diarrhoea in experimentally infected animal species, the key covariates 'experimental species', 'age' and 'immunosuppression' were significant (P≤0.2). Therefore, based on the results of this meta-analysis, these variables should be carefully reported and considered when designing experimental dose-response studies. Additionally, detection of possible publication bias highlights the need to publish additional studies that convey statistically non-significant as well as significant results in the future.