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CDC resorts to poop surveillance for future COVID monitoring..
According to the CDC, wastewater can detect variants and surges before testing.
The Centers for Disease Control and Prevention announced on Friday that it has publicly recorded SARSCoV2 levels found in sewers across the country. The announcement highlights the growth of sewage monitoring systems that the CDC will eventually target other infectious diseases.
Launched as a basic research in 2020, the system has grown into a network of more than 400 wastewater sampling sites nationwide, representing approximately 53 million American feces.The CDC is currently working with 37 states, 4 cities and 2 regions to add wastewater sampling sites. Health officials expect more 250 websites to be online in the coming weeks and more to be online in the coming months.
Dr. Amy Kirby, the CDC`s program lead for the National Wastewater Surveillance System (NWSS), called the sampling a vital early warning system for COVID-19 surges and variants, as well as "a new frontier of infectious disease surveillance in the US."
"Estimates suggest that between 40 and 80 percent of people with COVID-19 shed viral RNA [from SARS-CoV-2] in their feces, making wastewater and sewage an important opportunity for monitoring the spread of infection," Kirby said.
She added that the dropout began almost immediately after the infection, before someone showed symptoms, and sometimes a few days before a person got a positive test result. In addition, these signals in muck are not overwhelmed by test availability or access to health care.
So far, sewage tracking at various locations during the pandemic has washed away early signs of mutations and spikes, and in some cases announced a surge a few days ago.
Overall, trends in RNA levels in wastewater are closely linked to case numbers, hospitalization rates, and positive test rates, Kirby said.And that advance warning helps health authorities prevent a surge in anticipation.
For example, authorities may be able to direct mobile testing to communities found to have early elevated RNA levels, or increase the resources of hospitals in areas where cases are expected to increase.
The CDC's new NWSS data tracking page shows color-coded changes in RNA concentration at various wastewater monitoring sites. For example, in the blue area, the value has decreased by 100% in the last 15 days, but in the red area, it has increased by 1,000%.
Wastewater monitoring is especially useful for observing these trends, whether the cases are increasing or decreasing.
It does not provide a clear indication of the amount of SARSCoV2 in the population at any given time, and researchers do not know the threshold for detection. That is, it is unclear how many people must be infected in a particular sewage area in order for the sewage sample to be positive.
However, surveillance has clearly proven to be effective in finding future waves and their variants. For example, in a CDC study published late last month, Kirby reported that several wastewater monitoring sites detected the Omicron subspecies coronavirus before the cases of Omicron were detected in individual states.
As SARSCoV2 transitions from an acute pandemic stage to a quieter endemic stage, Kirby and her colleagues find that drainage detects local surges (probably seasonal surges) and the arrival of new variants. However, sampling is limited. Because we'll miss part of the US households(about 20 percent ) using sewerage systems instead of municipal sewerage.
Nevertheless, sampling has proven to be useful enough to convince the CDC to invest in more wastewater monitoring. In addition to additional sampling sites, Kirby plans to expand surveillance this year to include other pathogens such as influenza, the drug-resistant fungus Candida auris, and food-borne threats such as E. coli and norovirus.
By Ana C. / 16 Fev 2022
Ana C.
