Capitol News

Irene Xagoraraki, a professor of civil and environmental engineering at Michigan State University, has been investigating the potential of wastewater as a public health tool long before the COVID-19 pandemic brought it into the spotlight. Her environmental virology lab at MSU has partnered with the city of Detroit and the Great Lakes Water Authority since 2017 to test municipal wastewater from Wayne, Oakland, and Macomb counties for viral diseases in the Greater Detroit community.

Xagoraraki explains that wastewater is a mixture containing anything that goes down the drain, including stormwater and industrial water. It contains viruses and pathogens excreted by infected individuals, even before symptoms appear. These microorganisms are diluted in large amounts of water mixed with various chemicals and impurities.

"Looking for emerging human viruses in wastewater is like trying to find a needle in a haystack," she says. The process involves concentrating and isolating viruses from samples, extracting DNA or RNA, and analyzing them using molecular methods such as PCR and next-generation sequencing to identify viral infections present in the population.

The testing in metro Detroit involved collecting municipal wastewater as a representative composite sample from the community. Advanced molecular methods revealed endemic and emerging virus-related diseases circulating in the area. "We identified herpesviruses, including rare species, and we identified hepatitis A outbreak peaks via wastewater analysis that appeared before peaks in clinical samples," Xagoraraki notes.

The project shifted focus to monitor SARS-CoV-2 in 2020. The team expanded to include local health departments, practicing engineers, and the Michigan Department of Health and Human Services. They identified COVID-19 peaks five weeks before they were visible in positive test data during the delta variant surge.

To predict outbreak peaks, scientists consider variables such as virus shedding duration, onset of symptoms, and how long pathogens remain in wastewater pipes. This data helps relate wastewater readings to clinical disease metrics. Simple methods for data analysis have been developed for decision-making by public health officials.

An important step involves connecting viral readings with population estimates served by specific sewer systems using metabolites like creatine to calculate per capita trends. This allows comparisons between communities.

Public health officials use this data to get ahead of outbreaks. Clinicians report dozens of diseases to health departments when diagnosed. Xagoraraki's team developed a ranking system for prioritizing which reportable diseases future surveillance should focus on based on 12 factors including clinical trends and contagion levels.

"We also developed a sequencing and bioinformatics protocol," Xagoraraki adds. This step-by-step process screens for potential viral sequences circulating in communities beyond usual reportable diseases, providing an early warning if something new or unexpected appears in wastewater.