From COVID to gut microbiome: how wastewater serves to monitor human well-being

Since the beginning of modern epidemiology, a environmental monitoring of pathogens through surveillance of sewage water. It has mainly been used to follow germs that have a fecal-oral transmission. But new studies show that it is also a tool that can be useful for monitoring other types of diseases, such as fluthe covid and the monkey pox either Mpox.

A team of scientists led by Joshua Levy and Kristian Andersen, from the Scripp Institute for Translational Research in La Jolla, California, United States, highlighted the importance of strengthening studies through wastewater in the world. As they indicated, they allow observations of a wide diversity of pathogens in feces and detect outbreaks early.

“Today, wastewater is an essential component of infectious disease surveillance, providing a variant-specific and community-representative picture of public health trends that captures links of pathogen spread and transmission. that were not detected before,” they wrote in an article in the magazine Science.

During the last few years there have been analytical and laboratory advances to identify the various pathogens that are present in wastewater.

On the one hand, infectious diseases are monitored by testing and sequencing samples from affected people. “Pathogen surveillance typically involves sampling from infected individuals, which requires extensive sample acquisition, clinical testing, and coordinated sequencing between different centers and laboratories,” they stated.

They continued: “This type of clinical surveillance is expensive, time-consuming, and subject to bias due to disparities in public participation and the frequency of testing and sequencing, which can limit organizational preparedness and response.” public health response to outbreaks, especially in underserved communities.”

“While clinical surveillance will continue to be critical to responding to infectious diseases, wastewater-based approaches allow for rapid and cost-effective surveillance, even in current blind spots,” they stressed.

Wastewater surveillance allows rapid detection of pathogens and quantification of prevalence in the community. Pathogen concentrations accurately estimate prevalence (the number of current infections in the population). As wastewater trends often precede corresponding clinical detections, they may allow for early detection.

Wastewater can be used to track infectious disease dynamics from the community level to the building level, and from sources ranging from sewers and wastewater treatment plants to surface waters and point sources (e.g. , places of natural accumulation).

In many countries, wastewater treatment plants already collect composite samples of wastewater (taken regularly throughout the day) that can be analyzed to obtain essential information on the local prevalence of pathogens. These data allow for public health interventions.

In areas lacking centralized sewerage infrastructure, similar methods can be used to study surface water samples and point sources, although additional considerations of topography, water accumulation, and flow are needed to maximize basin size.

“However, to understand the determinants of pathogen incidence, including mutational changes, variant introductions, or emerging pathogens, genomic sequencing is necessary,” they cautioned.

During the coronavirus pandemic, analyzes based on wastewater sequencing have allowed the early detection of emerging variants, the estimation of their prevalence, the identification of the impact of specific mutations, among other parameters.

The ease of sharing sequencing data enables collaborative analysis of pathogen trends around the world. That possibility improves preparedness and informs public health guidance.

Although selective approaches are excellent for tracking known pathogens, they only examine a small fraction of the microbes present in wastewater. For a broader study of pathogens, nonselective metagenomic and metatranscriptomic sequencing methods can be used to identify any circulating microbial DNA or RNA.

A single sample can indicate the presence of viruses such as monkeypox and influenza, identify strains of pathogenic and antibiotic-resistant bacteria, detect protist parasites such as Plasmodium falciparum (causing malaria) and look for new pathogens, although standard methods may not be sensitive enough to detect rare pathogens.

“Moving towards more equitable and sustainable surveillance will require further development of local, self-sufficient scientific ecosystems through the development of laboratory and computational methods and training, capacity building and financial support for national scientific enterprises,” the scientists said. .

Expansion of wastewater metagenomic and multipathogenic sequencing activities is enabling extensive detection and genomic characterization of pathogens, including environmental contamination by the bacteria. Vibrio cholerae (causes cholera) in places without effective sewage treatment, rotaviruses transmitted by humans and cattle (causes gastroenteritis in children), and vaccine-derived polioviruses recently observed in London and New York.

Beyond infectious pathogens, “wastewater also has the potential to reveal changes in the human gut microbiome, which have been correlated with a wide range of health conditions and disease risks,” they reported.

Now is the opportunity to build on the momentum to form the backbone of future surveillance capabilities and scientific ecosystems around the world. Global surveillance networks that encourage the equitable sharing of technology, data sharing, and collective exploration of microbial diversity, both human and zoonotic, will be needed to help detect potential outbreaks and risks of spread.

The authors received grants from the National Institutes of Health (NIH), the National Center for the Advancement of Translational Sciences, and the Centers for Disease Control and Prevention.

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