2024-03-02 18:21:10
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Wastewater monitoring has long been a critical way to track a small group of deadly pathogens such as poliovirus
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- Author, Par David Cox
- Role, BBC Future
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7 hours ago
When he began his career as a microbiologist, Warish Ahmed never imagined that one of the most important roles of his career would involve sifting through gallons of raw sewage collected from pipes and drains. sewer in the state of Queensland, Australia.
“Dealing with wastewater may not be everyone’s favorite job,” says Ahmed, a senior researcher at the Commonwealth Scientific and Industrial Research Organization (CSIRO) Environment, in the city of Brisbane. “But I find it a valuable way to learn regarding community health. It’s like finding liquid gold,” he adds.
Wastewater monitoring has long been a critical way to track a small group of deadly pathogens such as poliovirus, Vibrio cholerae, the bacteria that causes cholera, and Salmonella typhi, the bacteria that causes typhoid fever, that are spreading all through poor sanitation practices.
But more recently, particularly in the wake of the Covid-19 pandemic, public health authorities around the world have begun to realize that studying the material in wastewater can be used to monitor a wide range of wastewater in real time. wider range of infectious diseases.
The project led by Ahmed and his team, in collaboration with the University of Queensland, examined levels of various respiratory pathogens such as influenza, SARS-CoV-2, which causes Covid-19, and RSV. All of these microorganisms are excreted through the intestines of infected people and are found in wastewater collected throughout the state. RSV is of particular interest because of the high mortality rates it causes in older adults, particularly those with pre-existing heart and lung conditions.
It is not just the presence of a particular pathogen that interests researchers, but its concentration. “Concentration is very useful for tracking the progression or decline of diseases,” says Ahmed. “High concentrations of a viral particle may suggest increased viral shedding in the community,” he adds.
When relayed to public health departments in the region, this information provides a critical early warning mechanism to signal the increased prevalence of a given infectious disease. Today, new technology platforms make it possible to collect this data even more efficiently.
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In 2022, poliovirus was detected in wastewater in several cities, including London and New York
Traditionally, wastewater monitoring involves unpleasant and dangerous work of manual sample collection. But in Queensland, every sewer is now equipped with an autosampler that collects samples every hour over a 24-hour period. These samples are then mixed to produce a mixture which can be analyzed in special facilities using PCR testing – a molecular technique which can be used to identify fragments of genetic material. In the United States, the Centers for Disease Control and Prevention now operates a national wastewater surveillance system that regularly screens for various pathogens, including monkeypox, using technology provided by Verily, an Alphabet company. .
Other startups, like Biobot, an MIT spinoff, are looking to expand wastewater monitoring around the world with their platform that can detect not only respiratory viruses in wastewater, but also human illnesses. food-borne such as norovirus, as well as the metabolized byproducts of drugs such as cocaine, fentanyl, methamphetamine and nicotine.
“With wastewater, it’s possible to monitor cities of millions of people using samples from just a few sites,” says Joshua Levy of Scripps Research, a nonprofit biomedical institute in San Diego. “Far fewer samples are required to meaningfully characterize local pathogen dynamics, compared to costly and bulky nasal swabs or blood draws, which are often confounded by disease severity. In contrast, infections asymptomatic are always detected by wastewater.”
Strengthening health security in low-income countries
While wastewater surveillance is widely used in the United States, Australia and the United Kingdom, where an ongoing program uses wastewater sampling to identify areas of the country at higher risk of polio, it Its greatest impact is likely to be in the management of epidemics in low-income countries.
Representatives of PolioPlus, Rotary International’s global polio eradication initiative, emphasize that while the incidence of polio has been reduced by 99.9% over the past 35 years, it remains a major global problem. public health in Pakistan and Afghanistan, where poliovirus is endemic.
“There are 114 wastewater monitoring sites in Pakistan and 33 in Afghanistan,” says Carol Pandak, director of PolioPlus. “Without monitoring, it would be impossible to determine where and how the poliovirus is still circulating.”
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Analyzing pathogens in wastewater can help scientists identify outbreaks before they get out of control
On the other side of the globe, wastewater monitoring is proving to be an essential tool for the São Paulo municipal government in its ongoing fight once morest hepatitis A virus (HAV), an infection that causes inflammation of the liver and sometimes requires a liver transplant.
In recent years, São Paulo has experienced two major HAV outbreaks, with 1,872 confirmed cases between 2016 and 2023. According to Tatiana Prado, a virologist at the Oswaldo Cruz Foundation, a research institute in Rio de Janeiro, the city has implemented a continuous wastewater monitoring program in certain airports and risk areas in order to control new emergences of HAV as well as other viruses and bacteria. She anticipates that new technologies will continue to improve the information these programs can provide.
“New diagnostic tools are emerging, capable of generating millions of data points on the different types of microorganisms circulating in a given environment,” explains Ms. Prado. “But the investment needed to maintain surveillance systems and interpret all the data generated, so that it is useful to policy makers, will be the main bottleneck.
Early warnings
With similar programs having been tested in parts of sub-Saharan Africa for tuberculosis and even for parasites such as Cryptosporidium, which causes diarrheal diseases, wastewater monitoring will undoubtedly play an increasingly important role in providing information to global health systems on all kinds of pathogens of concern.
In the coming years, researchers hope that real-time monitoring will begin to provide new information regarding the evolution of many common viruses, allowing them to predict whether they are at risk of evading existing vaccine immunity. This information might then be quickly transmitted to vaccine manufacturers, allowing them to update their vaccines before the newly evolved pathogen becomes more widespread in the community.
“Some researchers have shown that undetected circulation and evolution of common viruses is much more common than previously thought,” says Levy. “Work is underway to understand the importance of this phenomenon for major questions in virology, such as the emergence of variants of concern.
“It has been shown that we can detect the presence of new virus variants in wastewater 10 days or more before other forms of surveillance, providing critical time for public health officials and stakeholders to provide guidance , and for members of the public to modify their behavior if necessary,” he adds.
Similar information might also be used to preserve and protect antibiotics so that they continue to work for future generations, by examining wastewater samples for the presence of resistance genes – segments of DNA that give a bacteria’s ability to survive treatment with certain antibiotics.
Amy Pruden, a professor at Virginia Tech, says this type of surveillance might help locate communities that have the most problems with resistance, alerting doctors to potential infections spreading through the population and providing them with more information. information to be able to prescribe the most effective antibiotic.
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Image caption,
Although poliovirus is considered extinct in the wild, with the exception of Afghanistan and Pakistan, there are rare cases of vaccine-induced polio
“One idea that is gaining ground is the possibility of using metagenomic DNA sequencing,” says Pruden. “The beauty of this approach is that it allows you to sequence the DNA of all the bacteria present in wastewater at once, then compare it to databases and see what types of pathogens are likely to be present and what types of resistance genes they are likely to carry. The potential is enormous, but the application is only just beginning,” she adds.
The ultimate hope is that these surveillance efforts might also help detect future epidemics, or even pandemics, in the early stages, giving governments the opportunity to respond and direct efforts toward vaccine development. and medications much more quickly than before.
In the future, Ahmed’s team and other researchers around the world are investigating the possibility of analyzing the viral content of airplane wastewater, to spot possible new variants of influenza and Covid, or even new viruses transmitted from other parts of the world.
“It is essential to have the necessary tools in place before the next dangerous virus appears, so that we can combat it effectively,” concludes Mr. Ahmed.
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