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    CDC: National Wastewater Sewage Surveillance (NWSS)

    by Sheryl Hamlin

    The Water Environment Foundation ( hosted Dr. Amy Kirby of the CDC on July 15th 2020 to discuss National Wastewater Sewage Surveillance (NWSS), a program under development by the CDC and its partners. Read about the webinar here.

    Dr. Kirby explained how the use of sewage data complements existing public health efforts by providing infection trends, particularly in communities of sparse individual testing. Sewage analysis captures the existence of asymptomatic and pre-symptomatic conditions in the population, she said, and is a leading indicator, so even a few days’ advanced notice could save lives.

    CDC Model

    Sewage science is moving at a rapid pace, said Dr. Kirby. Sewage will become part of community health. Here is a recent article on advances in detecting the virus RNA in wastewater, a key element in testing.

    The CDC model predicts daily prevalence of infections in the community using the following parameters: concentration of Sars-Covid-2 in feces, amount of feces per person, amount of water used per person, decay of SARS-Covid-2 in sewage, fraction of water from source with potential infection, fraction of infections shedding virus, and concentration of SARS-Covid-2 in raw wastewater.

    A National Rollout

    NWSS bi-weekly samples will be shipped on ice to CDC labs for analysis and retention in the database. Funding will be provided to the participating water agencies.

    By changing the testing parameters, the labs can look for antibiotic resistance in wastewater.


    The aggressive timeline includes the development of a national standard for sewage testing.

    Immediately, there will not be enough government labs, she said, so the CDC will be soliciting lab partners, which might also include universities who are developing fields of study in this growing science.

    The partners in this program initially are the CDC, EPA and HHS. But, Dr Kirby indicated they have also been collaborating with other countries to share methodology. Countries mentioned were the Netherlands, Australia, New Zealand and potentially Spain.

    Caveats and Issues

    It is important to understand that the PCR test does not mean the virus is infectious and there are no tests confirming if the virus in feces is infectious.

    Water use affects the model, which is one of the noise factors which must be smoothed during the analysis.

    For more information, Dr. Kirby suggested the Water Research Foundation Summit papers.

    Sewage sludge has potential for use in detection, but work is needed for testing methods. Sludge could potentially be treated like a human sample (raw).

    Targeted Use

    The NWSS will not initially include targeted use due to collection issues, which were discussed in the previous article: Wastewater as Virus Detection Tool. However, Dr. Kirby indicated that targeted collection could be included.

    To view the webcast, click here.

    For more information on the author click sherylhamlin dot com

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    Dr Edo McGowan
    Dr Edo McGowan
    3 years ago

    Where, within the context of infectivity, does the viral viability cease, i.e., how far along within the sewer system does the virus remain hot. Not an opinion but a controlled study. Is the virus completely inactive in recycled water? Looking at recycled water from several treatment works and multiple samplings conducted at each facility over a 1-year period found Microorganisms in disinfected effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%; C. perfringens, 61%; F-specific coliphages, approximately 40%; and enteric viruses, 31%. Cryptosporidium oocysts and Giardia cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable Cryptosporidium, based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation was found for any indicator-pathogen combination. infectious Cryptosporidium, and infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed.

    Again, how far along within the system is the SARS CoV-2 potentially viable? Have there been any randomized tests on this?

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