Impact of Temperature Variations on the Viability and Infectivity of Sporulated Eimeria papillata Oocysts in C57BL/6 Mice

Abstract

Eimeria is a protozoan apicomplexan parasite that affects animals and poultries. This study investigated how temperature variations impact the inactivation of sporulated E. papillata oocysts during experimental infections in mice. A total of 20 male C57BL/6 mice were divided into four groups, with five mice in each group, as follows: Group 1: Control group – Group 2: Infected group inoculated with fresh oocysts (subjected to 23 ℃ for 7 days) – Group 3: Infected group inoculated with thermal oocysts (subjected to heating conditions at 100 ℃ for 60 min) – Group 4: Infected group inoculated with frozen oocysts (subjected to freezing at −20 ℃ for 7 days). An oral infection was initiated using 103 sporulated E. papillata oocysts to inoculate groups 2–4. Biological indicators, including body weight (BW) and feed intake (FI), were evaluated for each group. Oocyst output was assessed on day 5 post-infection. After sacrificing the mice, jejunal tissues were collected and processed for histopathological and biochemical analyses. Our findings indicated significant morphological alterations of sporulated Eimeria oocysts (i.e. a reduction in oocyst size and rounded shape of sporozoite) after being subjected to heating and freezing conditions. During the in vivo study, temperature treatment data shows significant inactivation of oocysts, with no fecal shedding. This result reflects enhancements in biological indicators and histopathological injuries, with the absence of intracellular Eimeria stages in the jejunal tissues, alongside a restoration of nutrient composition, particularly carbohydrates and proteins. Significant observations were also recorded regarding catalase (CAT), glutathione (GSH), nitric oxide (NO), and hydrogen peroxide (H2O2) levels. Temperature changes impact the viability of Eimeria oocysts and their role in coccidiosis. More research is needed on other biotic and abiotic factors in managing the disease.