Location: Animal Parasitic Diseases Laboratory
Project Number: 8042-32000-113-006-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jan 1, 2022
End Date: Jun 30, 2024
Objective:
The objective is to identify “the most effective chemical and physical methods to reduce or eliminate Cyclospora in agricultural water sources” and to establish “what real-life conditions and temporal parameters [induce] mature oocysts become infective or “die off.” At present, producers lack proven tools to mitigate risk and minimize liability.
Filtration’s performance against parasites in irrigation water remains unproven, and the scarcity of Cyclospora cayetanensis oocysts impedes research progress hastening control. Consequently, growers lack badly needed management tools to mitigate the risk of C. cayetanensis contamination in irrigation water used for fruit and vegetable crops. Using a carefully chosen, biologically appropriate and abundant parasite surrogate, the project team will hasten actionable insights. Specifically:
• Quantify oocyst removal from irrigation water via filtration.
• Determine whether filtration injures such parasites.
• Determine to what extent viability and infectiousness thereby decreases.
Approach:
The project will determine to what extent sand/iron filtration reduces oocyst abundance in pond water used for irrigation, using a non-zoonotic surrogate for Cyclospora (Eimeria acervulina, a closely related poultry parasite) by determining:
• Parasite reductions using filters of various ZVI/sand compositions.
• Filtration efficacy when parasites or other aqueous contaminants are abundant.
• Responses post filtration for sporulated and unsporulated oocysts.
The project team will evaluate whether and how filtration affects expression of oocyst viability genes via:
• qRT- PCR on validated viability targets.
• An Illumina Ampliseq NGS Panel targeting viability genes we have identified through RNASeq and qPCR.
The project team will evaluate whether filtration reduces parasite infectiousness by administering:
• 250 or 2,500 oocysts, pre- and post- filtration, to birds.
• 5 mL of pre- or post- filtration contaminated irrigation water to birds.
PVC columns will be filled with sand or a 50/50 mixture of sand with zero-valent iron particles (0.425 – 600 nm), minimizing air gaps. Surface water from either previously identified agricultural ponds or local creeks used in the CONSERVE project will be inoculated with Eimeria oocysts (of E. tenella or E. acervulina, sporulated or unsporulated), filtered, and the effluent will be recovered in pore volume portions. Effluent will be tested for Eimeria and naturally present E. coli as previously described. Parasites will be enumerated via microscopy, assayed in vitro for expression of viability biomarkers using qPCR and an Ampliseq panel, and bioassayed for infectiousness using chickens under an approved animal protocol. Should time and resources allow, the extent to which such filters capture fluorescent microspheres of comparable size to sporocysts of Cyclospora will be evaluated. The project will administer oocysts to chickens in numbers expected to yield 1,000-fold replication assuming they remain viable and unharmed. Dosage will be adjusted should initial experiments suggest more are needed to establish infection, or fewer are needed to discern reductions in fecundity.
