Sewage Surveillance Spots COVID-19 Spread
My recent blog postings have reported that researchers in the
Netherlands were the first to report that the
SARS-CoV-2 coronavirus, which appeared in late 2019,
could be detected in municipal wastewater systems.
That was followed by a report from France
which reported that the level of viral genetic material in untreated
sewage closely tracks the clinical case load.
That is, the more cases of COVID-19 that there are in a municipal area,
the higher the levels of SARS-CoV-2 genetic material to be found
in the sewage flowing into the wastewater treatment plant.
The researchers in both countries found that the virus could
be detected in sewage before the first cases were detected and
reported by public health officials.
Early detection of the virus within the sewage could help
health authorities start aggressive defenses early.
Mask-wearing and social distancing can save many lives
and prevent the potential spike in cases.
The World Health Organization declared the SARS-CoV-2 outbreak to be a
Public Health Emergency of International Concern on 30 January 2020,
and a pandemic on 11 March 2020.
A new study
posted to medRχiv
on 7 May 2020 added Italy to the list of
countries detecting early COVID-19 cases.
The study was soon
in Science of the Total Environment.
As that paper came out, the research team reported that they had
also detected the SARS-CoV-2 coronavirus in sewage samples
collected in December, before China reported its first cases.
SPQR utility cover in Rome, across the from Colisseum.
The official signature of the government of
Republican Rome was SPQR, standing
for Senatus Populusque Romanus
or "The Senate and the People of Rome".
Illustration of SARS-CoV-2 coronavirus created at the
US Centers for Disease Control and Prevention, from
The researchers, at Istituto Superiore di Sanità, in Rome,
collected raw sewage samples from several wastewater treatment plants.
The paper they posted in May 2020 described what they found
at two wastewater treatment plants in Milan,
and at two pipelines in Rome bringing wastewater from two
different districts of the city to a treatment plant.
As they described, Italy was among the most affected countries
in the COVID-19 pandemic.
It had become clear by the time of publication
that asymptomatic carriers contribute to the spread of the disease.
That interferes with analysis of SARS-CoV-2 circulation within a population.
They feel that WBE
or wastewater-based epidemiology,
which has already been applied to a wide range of waterborne, foodborne,
and fecal-oral viruses which are excreted in the feces,
is an important tool to fight the spread of COVID-19.
As an example, in 2013 Israel
the reintroduction and transmission
of wild poliovirus type 1 in monitored wastewater
before any clinical cases had been reported.
Remains of the latrines at the Roman Senate in Rome.
polymerase chain reaction,
is a technique now widely used to amplify,
or make millions to billions of copies of,
a very small sample of DNA.
It has been used to analyze ancient samples of DNA.
These researchers used RT-PCR, or
reverse transcription PCR,
to amplify and detect SARS-CoV-2 RNA.
Toilet at a café near the ruins in Paestum.
RT-PCR amplifies the RNA in the sample.
Now you need something to match it against.
Researchers have sequenced genomes of samples of SARS-CoV-2 from
Toilet in a hotel in Florence.
The Italian research team announced that they had discovered
SARS-CoV-2 RNA in Italian sewage back in December.
They had analyzed samples taken in northern Italy in October through
Recall that wastewater samples are collected and analyzed to watch
for many pathogens.
Toilet with a built-in bidet in a hotel in Perugia.
Samples collected in Milan and Turin on 18 December 2019 turned
out positive for SARS-CoV-2 RNA.
Both cities are in northern Italy where the pandemic infection rate
has been much much worse.
This was almost two weeks before China announced its first cases
on 31 December, and two months before the first clinical case in Italy.
Samples from November and October were negative.
Milan and Turin, plus Bologna, also in the north, were sources of
further RNA detections in January and February 2020.
Public bath in Pompeii.