Sewage surveillance

The Jackson Wastewater Treatment Plant sits next to the South Park Wildlife Habitat Management Area. Wastewater Manager Johnny Ziem found a way to have Teton County’s sewage influent tested for COVID-19, but pricing blocked the program, so Teton County Weed and Pest has taken up the mantle.

The Teton County Health Department announced Wednesday that it is getting help from fellow county agency Teton County Weed and Pest to monitor the spread of coronavirus in the community by testing the town’s wastewater.

“We just feel like this was another good overall data point for us,” public health coordinator Rachael Wheeler said of the new partnership.

The Health Department did a trial run of wastewater testing in April, working with a Boston-area startup called Biobot Analytics. The firm tested a few samples of wastewater, charging $100 for the kit and lab work.

But it raised its prices astronomically, asking roughly $1,200 per test by mid-June, so the county stopped the testing.

Sewage testing can’t specify who has the virus, nor can it give a specific number of cases in the community, but it still has useful information to offer.

“To be able to see if the COVID in the wastewater is going up or going down, it’s just good extra data,” Wheeler said.

Now that work has landed on the Weed and Pest lab. But Mikenna Smith, who will be doing the testing, doesn’t feel like it was dumped on her. Smith, an entomologist by trade, has experience doing the type of testing necessary to gather the data in the droppings.

People may be more familiar with polymerase chain reaction testing in a clinical setting, as it’s the same technology used in the nasal swabs doctors and nurses use to test patients for COVID-19. PCR testing, however, simply means amplifying a small piece of genetic material to test for the presence of the virus.

It can be done with samples from the nose or from sewage, though the process is decidedly different. The influent at the wastewater facility is sterilized, then strained and filtered to remove particulates. Solids are spun in a centrifuge to create a sample Smith can use in her PCR testing machine, which was originally purchased as part of Weed and Pest’s mosquito program.

“It’s not too complicated to just do it from wastewater,” Smith said, “but we did get a couple pieces of additional equipment to facilitate that step.”

The data from Biobot Analytics that came from the trial run showed higher estimates of case loads than direct tests of individual patients were showing.

That tracks with information from the Centers for Disease Control and Prevention, which says active-disease testing programs are not catching all cases.

The data from Weed and Pest will be used less to show discrepancies in testing and more to determine trends — for instance, whether the prevalence of COVID-19 rises or drops over the summer.

Testing hasn’t started quite yet, because Smith is waiting on one piece of equipment, but she already has her first samples and thinks she’ll be able to start next week.

Contact Tom Hallberg at 732-7079 or thallberg@jhnewsandguide.com.

Tom Hallberg covers a little bit of everything, from skiing to long-form feature stories. A Teton Valley, Idaho, transplant by way of Portland and Bend, Oregon, he spends his time outside work writing fiction, splitboarding and climbing.

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