Unalaska and Dutch Harbor sit 800 air miles away from Anchorage. And the community of about 4,500 year-round residents more than doubles during peak fishing seasons.
It’s one of few places in the state that has been largely untouched by the coronavirus. Since the onset of the pandemic, the community has only recorded 107 cases, 85 of which were from one factory trawler.
As part of its mitigation strategies, in July the island began testing its wastewater for traces of COVID-19, mirroring efforts by universities and municipalities across the country. And despite the island’s first case of community spread two weeks ago, the virus is still below the detection level to identify it in Unalaska’s waste.
At Unalaska’s wastewater treatment plant, about 350,000 gallons of waste and greywater run through the facility every day. That’s about 70 gallons per Unalaskan per day.
“If somebody has COVID-19, they’re shedding this virus in fragments,” said Karie Holtermann, lab manager at the plant. “It’s in their GI tract, they’re shedding it into their feces, into their urine. And so we’re trying to pick that up in our testing here.”
Holtermann has lived in Unalaska for about two years. Her background is in the public health sector as a microbiologist in Los Angeles and the San Francisco Bay Area, and she’s worked as a research technician and engineer in oceanography labs in San Diego, Seattle and on the Red Sea in Saudi Arabia.
She said sewage testing has been successfully used as a method for early detection of other diseases, such as polio. And at the start of the COVID-19 pandemic earlier this year, she saw a Netherlands-based study that concluded that wastewater serves as an early warning system for viral spread because it can detect virus in people who haven’t been tested or who have mild or no symptoms.
“What they’ve all seen is that wastewater monitoring can predict an outbreak a week before showing up at the clinic,” Holtermann explained. “And once it is shown that COVID-19 is in a community, it’s able to show the beginning, the tapering and the resurgence of an outbreak.”
About 77 universities in 27 countries are doing this testing — including University of Alaska Anchorage, which is partnering with communities around the state, according to Holtermann. To help Unalaska track community spread of the coronavirus, she got permission from the city to purchase the appropriate equipment, developed a method and then began testing Unalaska’s waste.
“The equipment that you need to be able to test for COVID-19 is a high speed centrifuge, a vortex mixer, micropipettes, a [quantitative PCR] machine, a spectrophotometer and consumables,” she said.
Every week since July, Holtermann has taken two to three wastewater samples from around Unalaska during peak flow times, dipping a bucket hanging from a rope down into a few of the 10 lift stations located around the island.
“We go all around the clock,” she said. “So, at midnight, three o’clock in the morning — it’s a very interesting view of Unalaska.”
Then Holtermann concentrates the samples in her lab using a high speed centrifuge, extracts RNA and turns it into DNA, and puts it in a quantitative PCR machine to make billions of copies of viral DNA. After about 24 hours, she tests the samples for SARS-CoV-2, the virus that causes COVID-19.
“But we haven’t gotten positives in the community yet,” Holtermann said.
And that’s good news, she said, because it means the levels of the virus in the community are still too low to detect. But she said that could change. If it does, this testing could be used to try to pinpoint where the positive cases are coming from.
“So you can’t target it to a certain house, by any means,” explained Holtermann. “But you can definitely look at a part of town — it may be on the Unalaska side, or it may be coming from the UniSea side, or it may be from the spit. So you could probably target which area it’s from.”
While the island has yet to see widespread transmission of the virus, local health officials say they anticipate more positive cases with the upcoming influx of workers for the winter fishing season. In the meantime, Holtermann said she’ll continue to test Unalaska’s wastewater every week and do her part to keep the island safe.
