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The latest on COVID-19 in Arizona.

How Wastewater Testing Serves as An Early Warning System For COVID-19 Infection Spikes


Yuma County is among the worst-hit communities by the COVID-19 pandemic.  


The County’s COVID-19 positivity test rate of 20 percent, compared to the state’s average of 14 percent, is an indicator of how much the virus is spreading. 

The University of Arizona’s Yuma Center of Excellence for Desert Agriculture, and state and local authorities, launched a wastewater testing project to try to get ahead of virus outbreaks. 

Wastewater testing can identify COVID-19 infection spikes in a community up to a week before laboratory testing.  

Paul Brierley, Executive Director of the Yuma Center of Excellence for Desert Agriculture says data collected from wastewater testing can be used to mobilize public health officials early.  

“If a particular area of the County is having a big increase or high infection rates, we work with public health officials and elected officials to decide on a response plan,” Brierley said." 

Brierley says the Center had agriculture workers in mind when they launched the wastewater testing project last summer.  

“Our biggest concern was, as the vegetable season started and we had 30,000 field workers, we didn’t want what happened in the meatpacking industry to happen here,” Brierley said.


According to the Midwest Center for Investigative Reporting, 45,000 meatpacking plant workers tested positive for COVID-19 at the beginning of the pandemic. 

 To prevent a major outbreak in the winter vegetable industry, Brierley says he and his team looked to a project in Tucson that was testing wastewater.  

“We thought if that works in a community like Tucson, we could define the community as anything we wanted, it could even be a labor crew of 30 people who all use the same outhouse,” Brierley says. 

Juan Guzman is Senior Vice-President of Operations at Datepac, a date packing facility in Yuma. 

Brierley and his team have been testing the wastewater from Datepac’s 200 employees twice a week since November.  

The testing has already prevented an outbreak at the facility. Guzman says a positive sampling was detected after the Thanksgiving holiday. 

“In this particular case, the people that tested positive work in specific, different areas so it could’ve easily spread all over the place if we hadn’t really caught it that way,” Guzman said. 

Guzman says they immediately contacted the Department of Health and Human services who mobilized a traveling testing unit from a local health clinic. 

He says every employee in the facility received a COVID-19 test within 48 hours, and 4 asymptomatic cases were detected. 

“Now we have information that we can immediately react to and by doing so we were able to possibly prevent a super spreader.” 

Flavio Marsiglia, Director of the Global Center for Applied Health Research at Arizona State University says wastewater testing can be a great tool to get a complete picture of how COVID-19 spreads in a community. 

But Marsiglia says wastewater testing is only effective if it is followed by a rapid response from public health officials and local authorities. 

“All these methods are good, as long as they lead to some action and change. If not, we are wasting our resources,” Marsiglia said. 

He says preventative measures like wastewater testing can help document and combat disparities when it comes to COVID-19 in vulnerable communities. 

“I think in our community, the Latino community, and I would say, the American Indian community and the African American community we know that people don’t have enough access to testing and that has been from the beginning. The communities are more vulnerable, but they have had a lower level of testing.” 

The Center’s Paul Brierley says his team will soon launch a county-wide monitoring program.  

They have already started testing the dormitories at Arizona Western College. He hopes to test the wastewater in municipalities across Yuma County as well as the Army’s Yuma Proving Ground and local Tribal Nations.