Maine’s rural population may explain fluctuations in COVID-19 wastewater levels
Maine’s rural population may explain fluctuations in COVID-19 wastewater levels

Maine’s rural population may explain fluctuations in COVID-19 wastewater levels

LEWISTON – Vigorous fluctuations from week to week in coronavirus levels detected in wastewater collected from public sewer systems across the country, including in Lewiston-Auburn, may be related to Maine’s rural population, the Maine Center for Disease Control and Prevention said.

“Wastewater screening for COVID-19 is still fairly new, so our researchers are continuing to explore the causes of the fluctuations,” Maine CDC spokesman Robert Long said in an email Tuesday.

“One hypothesis is that sewage systems in Maine tend to handle smaller volumes than sewage systems in more populous states,” he said.

As a result, fewer people with the virus can cause a larger increase compared to more populous areas.

In Portland, Maine’s most populous city, for example, it would take a “really significant increase” in the prevalence of COVID-19 to drive upward trends, Michael Abbott, who runs the Maine CDC’s wastewater monitoring program, told the website FiveThirtyEight .

In other words, wastewater testing, like other COVID-19 monitoring tools such as societal transmission levels, is a play with numbers.

And in Maine – where the population density per. square kilometers is less than four-fifths of the country – these numbers can be more challenging to interpret in rural parts of the state compared to more densely populated areas like Cumberland County.


In rural parts of the state, wastewater monitoring data “tend to jump up and down more instead of following a fairly smooth curve,” Abbott told FiveThirtyEight.

Wastewater testing is still an important tool for disease surveillance. Spikes in the level of coronavirus in wastewater can serve as a warning to public health experts and health providers to prepare for an increase in cases.

A report released by the Maine CDC last Thursday showed that wastewater samples collected in Maine over the past six weeks had a higher virus concentration than any other state in the country except Vermont.

After several weeks of declining hospital admissions in Maine, persons admitted with COVID-19 Tuesday represented a 33% increase over a week earlier, from 99 people on April 19 to 132.

Public health experts tend to regard hospitalizations as a delayed indicator of an increase in cases.

In a Twitter thread posted Monday, Maine CDC Director Dr. Nirav Shah that hospital admissions are increasing throughout the state.


“And the majority are hospitalized for COVID, not with COVID,” Shah wrote, emphasizing “for,” meaning that the primary reason these patients were hospitalized was symptoms related to COVID.

The Omicron variant continues to be the driving force behind cases in Maine. As of the Maine CDC’s most recent genome sequencing report released Monday, omicron and its sub-variants represented 100% of the samples collected so far this month.

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