Project seeks to shed light on Cyclospora prevalence

Project seeks to shed light on Cyclospora prevalence

Cyclospora has been linked to foodborne outbreaks that involved imported produce from Mexico and Central and South American countries where the pathogen is endemic. Currently little information is available about whether the organism is found in U.S. produce-growing regions and if so, how prevalent it is.

Dr. Gerardo "Jerry" Lopez, an assistant professor and extension specialist in the University of Arizona's School of Animal and Comparative Biomedical Sciences in Tucson, hopes to shed light on the pathogen with his project, "Cyclospora: Potential Reservoirs and Occurrence in Irrigation Waters."

Co-investigators are Drs. Paula Rivadeneira, Charles P. Gerba, Kelly Bright and Walter Betancourt, all with the University of Arizona.

"I think it's important that CPS put out a request for this study and that (the Center) wants to stay ahead of the game," Lopez said. "We want to look at this because we don't know very much about Cyclospora and its prevalence in the U.S. We understand there have been these foodborne outbreaks associated with imports, but what are we doing that's different so we don't see it here?"

The researchers are about one year into the two-year project that will focus on C. cayetanensis. Depending on the results, according to Lopez, they could show that existing food safety practices have helped significantly to reduce contamination risks tied to low Cyclospora populations. Should the research find higher pathogen levels, Lopez said he hoped to develop best management practices (BMPs) for the produce industry to help minimize associated risks.

As part of the project, local cooperators have begun collecting monthly water samples from irrigation canals in the Yuma, Arizona, and El Paso-Upper Rio Grande, Texas, produce-growing regions. Because of the shorter season in Texas, cooperator Roberto Rodriguez with the University of Texas will collect twice as many samples during the six-month growing season as counterparts in Arizona, who will collect them for the full 12 months. At the same time, they will collect monthly samples of raw sewage entering wastewater treatment plants as well as treated effluent leaving them.

"If Cyclospora is present, is the wastewater treatment plant taking care of it before it leaves the plant?" Lopez said. "A lot of this water is eventually discharged into the local watershed. This will allow us to identify if we're seeing it in the effluent, is it getting into the canal. So this will show the produce industry what some of the potential risks might be and how to mitigate them."

PCR assays, akin to genetic fingerprinting, will be run on all samples. Lopez has been working with colleagues in Japan to develop better detection methods. The TaqMan Probe, which uses different chemistry, appears to be more sensitive and more accurate than previous assays.As a protozoan, Cyclospora poses an additional challenge for researchers. Extracting the DNA, which is used in genetic fingerprinting, is much more difficult and complicated than from fungal or bacterial organisms. "It's been critical with this project to identify and develop the TaqMan assays that strengthen the detection of this organism," Lopez said.

Knowing the exact genetic make-up of the Cyclospora organisms could help the researchers track them to their source. If organisms show up in irrigation water samples, for example, are they the same genetically as the ones found in effluent samples? "I think this will allow us to gain a better understanding of whether it's indeed present in irrigation water and whether there is a relationship to where these wastewater treatment plants are or perhaps to leaky septic tanks," Lopez said. "This will be able to give us a better picture and be able to relate it."

The researchers also will be testing for coliforms in the irrigation and effluent samples to determine whether there is a correlation between coliform levels and the presence of Cyclospora.

Cultivating the next generation of researchers is almost as important as the research itself. Currently undergraduate minority students are getting their introduction to food safety science via Dr. Lopez's CPS funded project. The National Science Foundation grant, Western Alliance to Expand Student Opportunities, which provides underrepresented students first-hand exposure to the sciences, has partnered with the PI's and co-PI's for this project. Daniella Cabrera, a research technician who works with Lopez, has been teaching the students about the processes and technologies used in the project. "We have a couple of students who have been able to get engaged and study in this program," Lopez said. "It gives them the opportunity to do real-life research."

CPS Campaign for Produce Safety Contributors