"Testing wastewater gives you an idea of the number of cases within a community and whether the numbers increase or decrease", says researcher Ian Pepper.
Researchers are using municipal sewers to monitor the incidence coronavirus some sample communities in the USA.
The team says they can use wastewater surveillance to determine if the virus exists (and how widespread it is) in a community, even if people have no symptoms. The system can also monitor and ensure the effectiveness of a municipality's wastewater treatment process.
"Testing wastewater gives you an idea of the number of cases within a community and whether the numbers increase or decrease", he claims Ian Pepper, director of the Water and Energy Sustainable Technology Center (WEST) at the University of Arizona.
"The approach can also be used to help determine if an intervention is working to reduce virus transmission."
"We will be able to determine if the virus persists in the community even if there are no new cases reported", says Charles Gerba, microbiologist and professor of environmental sciences at the College of Agriculture and Life Sciences. "For me, it's a key to tracking the spread of a virus."
An illustrious precedent: poliovirus studies
Environmental microbiologists have used wastewater monitoring programs to study pathogenic viruses for decades, particularly in public health efforts to globally eradicate the virus responsible for poliomyelitis.
Through polio vaccine development and global vaccination programs, poliovirus transmission has decreased dramatically over the past 26 years. Only three countries in the world still have an ongoing broadcast: Nigeria, Afghanistan and Pakistan.
Because people can become infected without showing symptoms, experts have used environmental surveillance programs to detect silent transmission of the poliovirus through viral shedding present in community wastewater.
With advanced laboratory capabilities and experience in coronavirus research, the WEST Center can conduct wastewater surveillance for COVID-19 as well. Located within Arizona's Pima County Water Treatment Plant, the facility has extensive experience in detecting human pathogenic viruses in wastewater.
“We tested for hepatitis A, enteroviruses and noroviruses. We have about 15 different viruses that we regularly test in wastewater ", he claims Walter Betancourt, a microbiologist with experience in environmental virology and assistant research professor in the Department of Environmental Sciences.
Coronavirus in the sewers
The first coronavirus (named after the “crown” of spikes on its surface) was first identified in the mid-60s. Around the world, 7 different coronaviruses are known to infect people and cause disease. 4 of the coronaviruses are quite common. Three others, including MERS-CoV, SARS-CoV, and SARS-CoV-2, have emerged in recent years and are examples of zoonotic viruses that once only infected animals and have now made the species leap into humans.
COVID-19 is a new disease. There is still a lot to learn about transmission, the severity of the ailments it causes and the ability to spread.
The WEST Center conducted a study in 2008 that measured the survival of coronaviruses in sewers. He found that they die quickly, with a 99,9% reduction in two to three days.
With their wastewater surveillance program, researchers will use molecular and targeting methods of nucleic acid. Thanks to these methods, they will be able to detect SARS-CoV-2 genetic markers in samples collected before and after wastewater treatment.
Correlating viral concentrations in wastewater with the recorded number of infections is important. It can help public health authorities better prepare for the future.
Further coronavirus investigations are always welcome. Starting with sewer monitoring and next generation sequencing approaches. They can help identify circulating variants in the population and evaluate the effectiveness of mitigation strategies to control and prevent disease.
Photos: University of Arizona