Wastewater epidemiology used to stave off lettuce shortage

TUCSON, Ariz. (KOLD News 13) -The University of Arizona is leading the charge in studying wastewater for potential diseases, including COVID-19. Now, the work of epidemiologists could help save the nation from a leafy-green shortage, starting right here in Arizona.

Yuma produces the majority of the U.S. winter-time leafy greens. It’s a huge economic driver this time of year, and the population close to doubles with migrant workers and field producers.

“We have like 50,000 farm workers in the community,” said Paul Brierley, executive director at the UArizona Yuma Center of Excellence for Desert Agriculture. “How can we make Yuma a safe place to go back to work when the season starts back up.”

It was a question his team posed back in the summer and fall as COVID-19 cases were declining, and an ever-looming “second wave” was bound to approach. Sadly, as these areas grow, so have COVID-19 cases. Yuma County has more than 33,000 total cases, and about a 20 percent total positivity rate. This could hinder crop production for the U.S.

“What we didn’t want to have happen here is what happened in the meat packing plants where somebody got sick and they spread it…and they couldn’t function,” said Brierley.

To help get ahead of the curve, the University of Arizona expanded their wastewater epidemiology to the Yuma Center for Excellence in Desert Agriculture. In September, they launched a lab in Yuma. Before Christmas, the wastewater program had detected a positive result at a packing plant. The university said this led to the identification and isolation of about 5 asymptomatic employees—reducing potential exposure to hundreds of their co-workers.

“The week after that, we tested again and it was negative, no virus found in the wastewater,” said Brierley.

Just this month, the governor announced $500,000 in funding allowing UArizona to test wastewater within Yuma County’s municipalities—helping to shape and inform public health decisions. The pilot program is already being launched in four municipalities. Wastewater can be an early indicator of disease—several days or even a week before a person begins to show signs of a virus.

“When a particular area is experiencing a really rapid rise in infections…then they can deploy things like public information campaigns, or mobile testing units or things like that to those areas,” said Brierley.

Researchers plan to expand the use of the program within the community. When K-12 learning is back in person, they will start a 12 week pilot project to test an elementary school, a middle school, a high school, and a community college along with the other city wastewater in the same area. This will be an important project, showing how multi-jurisdictional areas could use this method to curb the spread of disease in the future.

UArizona’s wastewater testing program has spread around the nation, too. East Carolina University is following in UA’s footsteps. They will be testing wastewater at residence halls this semester to detect early outbreaks of COVID-19. An article from ECU said their school officials, “talked with staff at other universities such…the University of Arizona, which was one of the first in the nation to adopt wastewater screening among student populations and has served as a model for other institutions.”

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