Detectability and Persistence of Cyclospora cayetanensis Oocysts in Artificially Contaminated Soil and Fresh Herbs Grown Under Controlled Climatic Conditions

TL;DR

This study investigates how environmental factors affect the survival of Cyclospora oocysts in soil and herbs, finding that wet conditions support longer persistence.

Contribution

The study provides new insights into the environmental persistence of Cyclospora oocysts under controlled climatic conditions.

Findings

Cyclospora oocysts persisted longer in wet soil and herb leaves regardless of temperature.

Arid conditions led to shorter oocyst survival in certain soil types.

Herbs remained contaminated with oocysts under arid watering conditions throughout the study.

Abstract

Cyclospora oocysts are thought to be highly resistant in the environment but the climatic factors which determine the presence/persistence of Cyclospora oocysts are currently unknown. The main objective of this study was to determine the effects of temperature, water content, and soil texture on C. cayetanensis detection/persistence in artificially contaminated soil and herbs grown under controlled environmental conditions. Soil and leaves of three potted herbs (cilantro, parsley, and basil) grown in growth chambers and inoculated with C. cayetanensis oocysts were collected at 7, 14, 21, 28–31, 35–38, 42–45, 49–52, and 56 days post inoculation (dpi). Under wet watering conditions, independent of temperature, positive C. cayetanensis detection was observed at each sampling collection in both soil and herb leaves. Additionally, all three herbs were found to be positive for the parasite throughout the study duration in arid watering conditions. Conversely, short-lived persistence in soil was observed under arid conditions independent of temperature in Sandy Clay Loam soil (up to 14 dpi) and in Silt Loam soil (up to 21 dpi). Our results on the effect of desiccation on the presence and persistence of oocysts may provide useful insights for the proper cleaning and sanitizing of utensils or food contact surfaces to help control the persistence of the parasite.

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