Successful experimental infant baboon model for childhood cryptosporidiosis studies

Ngalla E Jillani,Atunga Nyachieo,James Nyabuga Nyariki,Daniel C Chai

doi:10.1186/s13071-021-04804-4

Ngalla E Jillani, Atunga Nyachieo + Show 2 more

Open Access

https://doi.org/10.1186/s13071-021-04804-4

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Abstract

BackgroundCryptosporidiosis causes high morbidity and mortality in children under 2 years of age globally. The lack of an appropriate animal model that mimics the pathogenesis of disease in humans has hampered the development and testing of potential therapeutic options. This study aimed to develop and validate an infant baboon infection model of cryptosporidiosis.MethodsEighteen immunocompetent weaned infant baboons aged 12 to 16 months were used. The animals were n = 3 controls and three experimental groups of n = 5 animals each inoculated with Cryptosporidium parvum oocysts as follows: group 1: 2 × 104, group 2: 2 × 105, group 3: 2 × 106 followed by daily fecal sampling for oocyst evaluation. Blood sampling for immunological assay was done on the day of infection and weekly thereafter until the end of the experiment, followed by necropsy and histopathology. Statistical analysis was performed using R, SPSS, and GraphPad Prism software. Analysis of variance (ANOVA) and Bonferroni post hoc tests were used for comparison of the means, with p < 0.05 considered as a significant difference. Correlation coefficient and probit analysis were also performed.ResultsIn all experimental animals but not controls, the onset of oocyst shedding occurred between days 2 and 4, with the highest oocyst shedding occurring between days 6 and 28. Histological analysis revealed parasite establishment only in infected animals. Levels of cytokines (TNF-α, IFN-γ, and IL-10) increased significantly in experimental groups compared to controls.ConclusionFor developing a reproducible infant baboon model, 2 × 104 oocysts were an effective minimum quantifiable experimental infection dose.Graphic abstract

Highlights

Cryptosporidiosis causes high morbidity and mortality in children under 2 years of age globally
While the incidence of cryptosporidiosis varies throughout the year, high levels occur during the warm rainy months [8]
In all experimental animals but not controls, the onset of oocyst shedding occurred between days 2 and 4 and continued throughout the experimental period, with the highest oocyst shedding consistently occurring between days 6 and 28

Summary

Introduction

Cryptosporidiosis causes high morbidity and mortality in children under 2 years of age globally. Besides the two main species of Cryptosporidium infecting humans, namely C. hominis (which infects humans only) and C. parvum (which infects both humans and bovines), other species such as C. suis, C. meleagridis, C. andersoni, C. felis, C. canis, C. muris, and C. baylei occasionally infect people as well [2, 3]. Jillani et al Parasites Vectors (2021) 14:316 excreted in feces can remain infectious for up to 2 months [10] This disease causes opportunistic infections in both immunocompetent and immunocompromised persons [5]. While the incidence of cryptosporidiosis varies throughout the year, high levels occur during the warm rainy months [8]

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