No sign of COVID-19 found in Cody sewage

Posted 5/19/20

Health officials have received another indication that COVID-19 has not been widely circulating in Park County.

Over the weekend, health officials learned that samples collected from the City of …

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No sign of COVID-19 found in Cody sewage


Health officials have received another indication that COVID-19 has not been widely circulating in Park County.

Over the weekend, health officials learned that samples collected from the City of Cody’s raw sewage late last month apparently contained no signs of the novel coronavirus.

It’s significant because people infected with the disease pass the genetic material from the SARS-CoV-2 viral genome in their stool. As a result, Biobot Analytics in Massachusetts — which analyzed the samples taken from Cody — can roughly estimate how many people are infected with the disease based on the prevalence of the virus in a community’s sewage.

But when Biobot tested Cody’s sample from April 28, the virus was “not detected,” according to a report provided to local officials on Sunday.

Combined with the fact that testing of hundreds of local residents has turned up just one confirmed case of COVID-19, “this suggests that we have been very successful in our local public health efforts,” Park County Health Officer Dr. Aaron Billin said Monday.

In a news release, the Park County COVID-19 Incident Management Team said the absence of the virus in the sewage was “a direct result of everyone’s hard work and dedication to our way of living” amid the pandemic.

“This is encouraging as we work towards recovery, but we must not let our guard down,” Billin said, noting an outbreak of nine cases at a Worland nursing home in recent days (see related story).

Additionally, late Monday night, after the Tribune went to press, Billin announced on Facebook that Park County had recorded its second positive test for COVID-19 at Powell Valley Healthcare.

City of Cody wastewater workers plan to collect a second sample later this week, with a third test likely to be conducted either next week or in early June, said Cody Public Works Director Phillip Bowman.

While the first test was meant to set a baseline, subsequent tests are intended to track whether the prevalence of COVID-19 is increasing in Cody sewage — particularly as tourists from across the country and globe begin to arrive in the area.

Bowman said it was good to see the absence of the virus in the city’s sewage.

“But I think the importance of it is really going to be moving forward,” he said, “and especially if we do have a summer visitor season develop and be able to identify if there are cases, [COVID-19] positive individuals coming into our community.”

Billin has described the wastewater epidemiology as potentially serving as an early warning sign of an outbreak and that it could help inform public health decisions. However, it’s only one point of data being considered.

“This isn’t going to be the be all, end all,” said Jack Tatum, Park County’s homeland security director, earlier this month.

For instance, Billin said this weekend that public health officials “are working on organizing a surveillance program to test random staff of Cody businesses that will have a lot of contact with out-of-state visitors.”

He said hotels and motels are being encouraged to screen all their guests for symptoms of COVID-19 and to urge sick guests to seek care.

When asked by a Facebook user on Sunday whether retailers might be included in the surveillance efforts, Billin said public health officials are still working on the plan.

“Unfortunately, this is limited by available money and personnel,” he said.

Biobot has been charging $120 per test, basically offering the testing at cost as a pro bono effort, Bowman said. The lab says it’s been processing weekly samples from 350 sewage treatment facilities in more than 40 states.

However, starting in June, the company is charging $1,200 a test, which will factor into how frequently health officials decide to test Cody’s sewage.

The City of Cody should soon receive a portable, automated composite sampler which will be able to collect samples from the city’s sewage stream every hour; the city spent about $9,500 on the device, Bowman said.

However, for the first set of samples collected on April 28, city workers had to manually collect samples at the pretreatment building, where all of the city’s sewage gathers.

“At that location, the wastewater is at its … completely untreated form; it’s the most raw, before we start any processing,” Bowman explained. “So that’s where we sample it.”

Using a device that’s basically “a bucket on the end of a stick,” Bowman said city personnel took samples at the building every two hours over a 24-hour period.

All told, they collected two to three gallons of material, then mixed it up to make a composite of all the samples.

“The premise behind a laboratory test is if you have a 24-hour composite you’re sampling one full day of waste generation from your community,” Bowman explained. “So if there is any genetic material being passed from ... folks with positive COVID cases, that would, in theory, be caught across that 24-period.”

A small portion of the mixture — roughly half-a liter — was then shipped off to the Biobot lab.

Park County officials were told to expect an eight- to 10-day turnaround between the time that samples are submitted to the company and when results are ready. With that kind of a turnaround, it’s “very usable data,” Billin has said; a two- to three-week lag, however, would make the results much less usable, he said.

It wound up taking roughly 17 days for Park County to receive results from the first sample; Billin said the county was told the delay was due to several Biobot lab staffers being quarantined “due to an exposure.”