COVID sewershed testing project releases new storymap
The Missouri Department of Health and Senior Services, Department of Natural Resources and researchers at the University of Missouri have been collaborating on a statewide project to test domestic wastewater for genetic markers of SARS-CoV-2, the virus that causes COVID-19.
Missouri’s Coronavirus Sewershed Surveillance Project is funded by a Centers for Disease Control and Prevention Epidemiology and Laboratory Capacity grant, Environmental Public Health Tracking and federal CARES funds.
Studies in the Netherlands, Italy and United States found a direct correlation between the amount of SARS-CoV-2 genetic material in sewage and the number of reported cases within a given “sewershed,” or the area that drains into a community’s wastewater collection system.
While the virus that causes COVID-19 is new, using wastewater for tracking disease is not. According to the Department of Health and Senior Services Public Health Tracking team, wastewater testing has proven useful in tracking diseases such as polio and norovirus, and is becoming a useful tool for SARS-CoV-2 surveillance. The SARS-CoV-2 virus particles are shed in human feces by many infected individuals, including those who are symptomatic and asymptomatic. These particles can be detected in wastewater by testing for specific genetic markers.
Wastewater is not known to be a transmission pathway for the virus.
The sewershed surveillance project is currently testing 59 community wastewater facilities weekly and has tested more than 2,000 samples to date, generating enough data to provide meaningful statistics for interpretation. These findings currently indicate sewershed testing best correlates with human case data with a 4 to 6 day lag, meaning this may be an early indication of increasing trends of COVID cases.
The data also shows that a 40% increase in sewershed viral load over a week, or two consecutive weeks of 25% increases or greater, is followed by at least a 25% increase in measured human cases about 70% of the time. This level of agreement is evident even given the variability across sewersheds in wastewater flow rates, chemical matrices, industrial activities, population changes, rates of human COVID-19 testing and other factors.
The sewershed surveillance team developed a storymap to display these results. The storymap (storymaps.arcgis.com/stories/f7f5492486114da6b5d6fdc07f81aacf) contains an interactive map displaying sewershed trends and identifying those found to have a significant increase in the viral particles measured. The interactive map also identifies sewersheds with little to no change in the trend but remain elevated.
Individuals can select specific sewersheds and see their sample results. Because of the numerous variations from one sewershed to another, it is not possible to directly compare sewershed readings between facilities and communities.
“As the outbreak continues, this program remains an effective tool for trends analysis to be used with other measures of viral spread in a monitored population,” said Jeff Wenzel, Bureau Chief of DHSS’s Bureau of Environmental Epidemiology.
For more information about the sewershed surveillance project, contact the Department of Health and Senior Services Environmental Public Health Tracking Team at EPHTN@health.mo.gov or 866-628-9891 or 573-751-6102.