Gambier Wastewater Report

Gambier Wastewater SARS-CoV-2 Virus Report

Wastewater SignalGambier

The Village of Gambier and Kenyon College are sampling wastewater for levels of RNA from dead coronavirus SARS-CoV-2, the cause of COVID-19 disease.
● Blue symbols represent log2 concentration (doublings) of dead viral RNA per liter, reported by Source Molecular.
ⲻ ⲻ Dashed line represents a two-sample rolling average (revised from three-sample)
Red symbols represent COVID cases resident or employed in Village of Gambier on dates that results were received at
Knox Public Health
. Recent case reports are delayed due to overwhelming case numbers at KPH.

This model is experimental and updates frequently. For questions or to receive regular updates: slonczewski [at]

What do the recent virus levels mean?

  • Current virus levels above 500 RNA per liter (29 = 512) indicate several active infections in the Village, not yet reported. The wastewater signal often appears two weeks before KPH case reports.
  • Wastewater can detect infectious cases before the individual experiences symptoms. Before symptoms, the infection may already have spread to others. Cases can be asymptomatic.
  • Mask and physical distancing can prevent their spread.
Virus spread time course

Does a non-detect (failure to find virus) mean no virus is present?

  • No, because failure of virus detection in one sample means that wastewater substances could have inhibited the lab reaction.
  • Single cases may avoid detection, just like a single case by RT-PCR swab test (30% false negative).
  • Two or more non-detects suggest that virus levels are too low for detection.
  • It takes just one unlucky breath to start a new cluster.
Who is represented in the sample?
  • The sample represents all individuals whose waste enters the Gambier wastewater treatment plant. This includes most village resident, employees at local businesses and Kenyon College, including all students on campus.
  • The sample does not include residences using septic fields, outside the wastewater system.
  • The total village population in August was estimated at 700 individuals. By September, the total is approximately 1,600 including an approximate number of 920 students on campus.
How many people in Gambier are infected?
  • The wastewater virus cannot distinguish between a number of individuals versus a large amount spreading from one individual.
  • Individuals from outside the village are not detected since their wastewater does not enter the Gambier plant.
Will infected people get sick?
  • Most people infected with SARS-CoV-2 experience no symptoms, or mild symptoms. Their cases may or may not be reported.
  • However people without symptoms may spread virus to others who get very sick.
  • Wearing a mask protects others--and protects you from getting large doses of virus that cause more severe illness.

Where do the data come from?

  • Composite samples (over the most recent 24-hour period) are obtained from the Gambier Wastewater Treatment Plant on Monday and Thursday mornings.
  • Samples are processed by Source Molecular laboratory, where virus RNA is amplified using CDC-approved primer sets N1 and N2.
  • Results are obtained within four days of the sample.
  • The data are interpreted by Kenyon faculty, in consultation with the OSU Water Resources Center, Ohio Department of Health and EPA collaboration for wastewater testing research.

Why do virus levels show high variance?

  • Wastewater composition varies with weather and inputs. The presence of PCR inhibitors is variable.
  • Different infected individuals shed different amounts of virus.
  • A single individual may infect many people at once, leading to a spike in signal that declines as cases resolve.
  • The rolling average removes much of the variance.

Why is there virus present when only occasional cases of illness are reported?

  • Some infected individuals show no symptoms yet they shed virus particles and can transmit infection. The relationship between reported and asymptomatic cases in a hypothetical community is illustrated in this diagram (illustration only, no data).

    Hypothetical Case Reports
    Hypothetical Undetected Cases

How do Gambier levels of virus RNA compare with the rest of Knox County?

  • Gambier's smaller population shows greater fluctuation in virus levels than the larger populations.
  • In September, the Gambier virus level may be lower than in Mount Vernon, but in July, Gambier had higher virus per person than Mount Vernon.
Can the wastewater test show how many individuals are infected?
  • The wastewater signal shows only changes in overall virus shed collectively. Wastewater cannot distinguish between, for example, ten infected individuals versus one individual who sheds ten times as much virus.
  • However, a rise in virus levels may indicate a rise in infections, which lead to increased case reports.

Is wastewater SARS-CoV-2 virus a danger to the community?

  • No, because the SARS-CoV-2 coronavirus in wastewater is dead virus. Only RNA pieces of dead virus are detected.
  • All wastewater is handled with PPE and shipped under regulated conditions.

What is happening to virus levels in the broader community?

  • Current virus levels are rising throughout Ohio.
  • Mask wearing and physical distancing are the best ways to keep virus prevalence low.
  • Masks prevent infecting others and decrease the amount of virus that reaches the wearer.