Jan. 1, 2022 - Dec. 31, 2023Amount Awarded
Benjamin Rosenthal, S.D.
USDA - ARS
Jitender P. Dubey, M.V.Sc., Ph.D., Mark C. Jenkins, Ph.D., Manan Sharma, Ph.D., Kalmia E. Kniel, Ph.D.Summary
The reputation of growers and the health of consumers suffer when people contract foodborne illness from fresh produce contaminated with Cyclospora cayetanensis. Because filtration has been established as effective in concentrating parasites for environmental surveillance, we propose to establish how effectively filters remove such parasites from irrigation water. To achieve this, we will first conduct a series of filtration experiments using abundant parasites (of chickens) that pose no risk to the study team. We’ll then assess how well these filters reduce water contamination with Cyclospora. We will also determine whether any parasites surviving filtration are harmed in the process. We hope these findings will directly benefit growers seeking tools to mitigate risk, and hasten future research progress by validating a needed surrogate system for studying other interventions against this dangerous and enigmatic human parasite.
Outbreaks of cyclosporiasis threaten human health and impose liabilities to growers (Almeria et al, 2019; Dubey, 2020) necessitating better preventative tools. Irrigation water represents a source of contamination (Kitajima et al, 2014). Zero-valent ion (ZVI)/sand filtration improves the microbial quality of agricultural water without disinfectant chemicals. Permeable reactive barriers (PRBs) with bio-sand and ZVI filters remove groundwater chemical contaminants (such as bromate), reduce viral loads by 5-logs, bacterial fecal coliform levels in river water by 1 log CFU, and inactivate E. coli and Listeria. (You et al, 2005; Ingram et al, 2012; Shearer and Kniel, 2018; Marik et al 2019). Inactivation varies with contact time, particle size, solution pH, dissolved oxygen, concentration of ions, and redox potential (Sharma et al. 2020). More than three-log reductions have been achieved using filtration against Cryptosporidium parasites (Nascimento et al, 2020). Filtration has recently been established to enhance surveillance for Cyclospora (Durigan et al. 2020) but has not yet been proven as a means of prevention. Here we propose a series of experiments to determine how well such filters remove, and/or harm, parasites contaminating irrigation water. We will establish assay conditions first using parasite-sized fluorescent microspheres. We will then conduct extensive studies using abundant (non-zoonotic) Eimeria parasites of chickens. Those data will govern experiments directly evaluating the capacity of ZVI filters to mitigate the risk of foodborne cyclosporiasis by removing and/or injuring such parasites. In addition, this work will test new in vitro viability assays, establish whether filter efficacy against parasites can be predicted from widely-used E.coli counts, and will hasten future progress by determining whether fluorescent microspheres accurately model parasite responses to filtration.