Department of Health urges wastewater testing to detect COVID


SHERIDAN — The Wyoming Department of Corrections recently completed COVID-19 testing on staff and inmates at the Wyoming Honor Farm and state penitentiary. The honor farm returned no positive cases but 15 inmates, two staff members and seven contract health care workers at the penitentiary tested positive.

In the announcement with updated case numbers, WYDOC cited new plans to conduct wastewater sampling at facilities — an initiative supported by the Wyoming Department of Health to obtain more objective models of community spread in the state.

WYDH Chief Data Analyst Franz Fuchs said wastewater sampling has not proven 100% accurate for testing this particular virus as there is no previous data with which to compare.

Still, despite the unknowns, the virus has been shown to shed in feces, so a representative sample could be obtained on a broader community scale rather than testing house by house — essentially because everyone poops.

Wastewater sampling does not require individuals to obtain a diagnostic test to model community prevalence, Fuchs explained. Asymptomatic carriers still reveal the virus through their waste.

In theory, wastewater testing may offer the public a more objective sense of exposure risk surrounding them, whether high or low, he said. Wastewater testing is essentially the same process as testing an individual diagnostic swab for COVID-19.

The testing process considers the virus’ half-life and degradation in the sewer — when compared to total gallons of wastewater, lab technicians can estimate the actual infection rate in the community.

For now, artificial data is being used in simulations but analysts will never know if their model will ever capture true prevalence, Fuchs said. The theory is promising but as far as assumptions within the model, “the devil is in the details,” he said.

At the very least, technicians and statisticians can provide public health officials and lawmakers with an indication of prevalence and trends over time to inform policy and target decision-making.

If every city in the state participated, WYDH could objectively compare the worst and best outbreak locations to take informed management action rather than allowing panic to drive decisions, Fuchs said.

The city of Cody began wastewater sampling back in May and WYDH took a cue — state health officials recognized the value of what the municipality endeavored to capture with sampling and dedicated CARES Act funds to improving capacity at the state laboratory with specialized equipment necessary for testing wastewater samples.

WYDH provides technical assistance and reimbursement for costs associated with testing — including shipping costs for sample kits — so there is no expense to municipalities, Fuchs said. With such scattered data points, widespread participation will help improve the effort’s accuracy.

After just beginning this initiative, WYDH has seven to 10 cities in various stages of participation, including Sheridan. The overall goal is to obtain two samples per week per city.

WYDH is also working with the University of Wyoming to stand up another lab to handle additional sample volume if necessary, so samples can be processed in two to three days.

Doug Rideout, Sheridan Wastewater Treatment Plant superintendent, said he was approached by WYDH and as a group, he and his staff found value in providing the city of Sheridan with helpful data about signs of COVID-19 in the community.

Of two samples submitted in July, one result came back positive. Rideout said it will take time before compiled data begins to show trends and reliability in wastewater sampling but eventually, analysts can compare results from the wastewater plant with Sheridan Memorial Hospital testing.

More cities around the U.S. are considering this sampling method as an early warning system for community spread — if numbers begin to decline or spike in wastewater, hospitals will know there may be up to two weeks to prepare for a rise in cases, Rideout said.

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