Wastewater provides clues to COVID-19’s next move in Allegheny County
Wastewater provides clues to COVID-19’s next move in Allegheny County

Wastewater provides clues to COVID-19’s next move in Allegheny County

Last week, Allegheny County’s health department reported fewer than 100 new cases of COVID-19 a day. But the growing use of home testing combined with an overall decline in people being tested for COVID-19 makes it hard to know if this is really a milestone.

A 100 foot deep well with raw wastewater may contain the answers.

Skimming of data

The Wastewater Well is the site where wastewater from Pittsburgh and 82 other municipalities enters the Allegheny County Sanitary Authority, located on the banks of the Ohio River.

“There has been no screening, filtration, no disinfectant,” explained Doug Jackson, ALCOSAN’s Director of Operations and Maintenance. “This is as raw as the wastewater gets that enters the treatment plant.”

COVID-19 is excreted in the feces, and since this fall, the Allegheny County Health Department says it has analyzed ALCOSAN wastewater for the virus.

Sample collection takes place in an adjacent building to the well. Wastewater flows into a container that is roughly the size of an extra large box of grain. Every 10 to 15 minutes, transfer a small amount of water to a 2.5-liter plastic bottle. The remaining liquid is then emptied and the process repeated so that the bottle is slowly filled over 12 hours.

The 100-foot well at the Allegheny County Sanitary Authority is where raw wastewater enters the facility.

A commercial laboratory is currently conducting the actual analysis in Florida. The county’s health department Dr. Robert Wadowsky said it takes at least a week to get results on how much COVID-19 is in the water supply, and then about a week to determine which variants are present.

Waiting that long reduces the value of the information to act as an early warning system for potential increases. For example, the county only learned that omicron was present in its wastewater a day or two before the first people tested positive for the variant, which is now dominant in the county.

In addition, current methods can not distinguish between sub-variants and therefore can not provide data on omicron’s sister tribe, which drives cases up in other parts of the world. While individual residents of Allegheny County have tested positive for the subvariant, both wastewater data and raw case data show that local transmission continues to decline.

Nevertheless, wastewater monitoring is a powerful tool, and therefore the National Board of Health will start doing this analysis internally.

“We have the technology ready to go, almost … but it’s so hard for us to hire staff to work in the lab,” said Wadowsky, director of the department’s public health lab.

The county is collaborating with researchers at Carnegie Mellon University to conduct this analysis and create an online dashboard so the public can see the data that Wadowsky predicts will launch later this spring.

What is reflected in the wastewater?

According to data from the county’s health department, in early March, when the county reported about 100 cases a day, the presence of COVID-19 in the wastewater was slightly below where it was around Halloween. At that time, the daily number of cases exceeded 300.

Wastewater collection

The Allegheny County Sanitary Authority takes samples of wastewater to monitor for COVID-19 as well as for commercial and industrial pollutants.

While test numbers and wastewater data are not entirely consistent, the analysis follows the same general pattern of hospital admissions in the county with a significant increase that peaked in early January, followed by a steep and rapid decline. This is significant because even though only a fraction of people who get coronavirus become seriously ill, the percentage of those who develop severe COVID-19 is relatively stable.

Sampling of wastewater for public health monitoring is not new – it has been done for opioids, HIV and antibiotics, to name a few. But it became more common during the pandemic, and last month the Centers for Disease Control and Prevention launched one dashboard detection of COVID-19 in wastewater at more than 400 locations. There are so many applications because it captures populations that other methods miss.

“People who do not have access to care, who do not have insurance and therefore do not go to the doctor, and therefore can not be counted through traditional hospital-based or clinic-based monitoring, they still flush the toilet. , ”Said epidemiologist Matt Ferrari, director of Penn State’s Center for Infectious Disease Dynamics.

All of these bathroom breaks create lots of data, which means greater sensitivity to subtle changes in transmission. For example, in areas where polio has been virtually eliminated, wastewater analysis can tell health professionals if there are cases they are unaware of.

“And it then warns them, ‘OK, we’ve seen it in sewage,'” Ferrari said. “Now we need to look more at people.”

In addition to COVID-19

Wadowsky admits he was initially skeptical that the wastewater analysis would be effective. That changed when he saw the consistency of the data.

“I thought for sure there would be so many fluctuations,” he said. “So I was really surprised. “

For this reason, he sees other possible uses, such as monitoring for an enterovirus that causes acute flaccid myelitis – a rare but serious polio-like disease most commonly seen in young children. The CDC reports that there have been only 679 confirmed cases since August 2014. Only between 20-30% of patients recover completely.

Meanwhile, the county will continue to watch for signs of COVID-19 increases in wastewater. At the moment, the wastewater looks calm.


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