Sewage testing has captured rising levels of COVID and even evidence of polio. Can you predict new viral outbreaks?
Yogi Berra said it well: “It’s hard to make predictions, especially about the future.”
Although he wasn’t talking about viral infections or the current pandemic, he might as well have been. Even the best scientists, infectious disease specialists, and epidemiologists have found it difficult to accurately predict when new viral outbreaks will appear (think COVID-19), when old ones will reappear (think polio), and how to resolve this in time to do the difference. But what if they could? An already available tool called a sewage test is showing promise, and how we use the results could help slow the next surge of COVID or predict the emergence of a surprising new virus.
COVID: When can we expect the next spike?
For months now, the US has recorded more than 100,000 new cases of COVID-19 and 300 deaths each day. And, in fact, the number of cases is likely to be much higher because testing rates have dropped and positive home tests are not included in official counts. With numbers like these and the emergence of new variants, it seems inevitable that more cases will increase.
But when?
Perhaps in the coming weeks, as new highly contagious variants spread. Or possibly in the fall and winter, as we spend more time indoors. Or maybe this virus will surprise us again and wait until next year to resurface.
A big challenge in containing the COVID-19 pandemic is that by the time we know infections are rising rapidly in a community, it has already been going on for some time. Because people often have no symptoms initially, the infection can spread for a time without warning.
If we could predict when the next rally will occur, we may be able to take the proper preventative measures. And that’s where your feces (feces, poop, whatever you prefer to call it) come in.
Detection of viral outbreaks using wastewater
The idea is simple: when people have a viral infection, the virus can often be detected in their stool. Therefore, sewage from a town or city, or perhaps from a community, can be tested for viruses and, if so, whether the amount increases over time.
This approach has been used since the 1940s, when polio was of great concern. But sewage tests can also be used to detect various types of hepatitis, the flu-like norovirus, and possibly measles.
The methods used to analyze wastewater have improved over time. Early efforts attempted to grow viruses from water samples; more recently, testing has moved toward detection of viral genetic material.
Polio and COVID in sewage
In June 2022, testing of sewage in London detected the virus that causes polio, a life-threatening or disabling disease. Although no active cases of polio have yet been diagnosed in London, this finding has triggered an investigation into where the virus originated, who might be infected and whether there are any public health threats.
In the US, a New York county that had been testing wastewater for COVID levels also began polio testing after an active case of polio occurred in an unvaccinated adult.
Has wastewater testing been shown to be useful in detecting and tracking SARS CoV2, the virus that causes COVID-19? In fact, it has. Levels of this virus in sewage have closely mirrored infection rates in many cities around the world, and in some cases predicted an outbreak before a community had even noticed that cases were rising. The CDC now includes wastewater data in its regular reporting of COVID-19 infection rates.
Wastewater test results are usually combined with other information, such as infection rates reported by hospitals and doctors’ offices, infection trends in nearby communities, and vaccination rates. Taken together, this information gives public health officials better insight into a range of viral infections of concern and where case numbers may be heading.
How is wastewater data useful?
Detecting the presence or increased level of viruses in wastewater can help public health officials, health care providers, and researchers.
predict when a surge is occurring or when it is at its peak update messaging on prevention measures (for example, advice to wear a mask in public spaces or physically distance) order more vaccines and antiviral drugs encourage more testing identify new variants.
Letting people know if cases are increasing in their community can be particularly important for those who face barriers to getting tested, including people who don’t have health insurance or a primary care doctor. Wastewater testing can be particularly useful when undercounting is common, as in the case of COVID-19.
In the future, sewage testing could improve to the point where we can narrow down the site of an outbreak to a single neighborhood or residential facility, such as a nursing home or prison.
The bottom line
Unfortunately, the COVID-19 pandemic is not over. And we are hearing alarming reports about the international spread of the virus that causes monkeypox. In the future, it is very likely that old viruses such as polio and measles will resurface and new pandemics will emerge.
We will need all the help we can get to stay ahead of these outbreaks. Some of that help is likely to come from sewage. So, oddly enough, what you flush down the toilet can help health officials detect, and possibly even contain, a public health threat.
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Source: www.health.harvard.edu