Gambier Wastewater SARS-CoV-2
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.
model is experimental and updates frequently. For
questions or to receive regular updates:
What do the recent virus levels mean?
- Current virus
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.
a non-detect (failure to find virus) mean no virus is
Who is represented in the
- 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
- It takes just one
unlucky breath to start a new cluster.
How many people in Gambier are infected?
- 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
- 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.
Will infected people get sick?
- The wastewater virus cannot distinguish between a number of
individuals versus a large amount spreading from one
- Individuals from outside the village are not detected since
their wastewater does not enter the Gambier plant.
- 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
do the data come from?
samples (over the most recent 24-hour period) are obtained
from the Gambier Wastewater Treatment Plant on Monday and
- 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.
do virus levels show high variance?
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.
is there virus present when only occasional cases of illness
- 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).
do Gambier levels of virus RNA compare with the rest of Knox
Can the wastewater
test show how many individuals are infected?
- 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
- 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.
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
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.