Wastewater pathogen surveillance based on One Health approach

Wastewater-based epidemiology (WBE) has been widely used for investigating drug misuse, emergence of antimicrobial resistance, surveillance of poliovirus, and early detection of possible SARS-CoV-2 outbreaks.¹ The surveillance of SARS-CoV-2 in wastewater has been done in more than 3892 sites in 70 countries or regions because this approach is a rapid and cost-effective way of monitoring COVID-19 outbreaks. However, these tested sites are mainly concentrated in highly populous communities, universities, and transportation hubs. The tests focus on pathogens circulating in humans, and ignore the surveillance of pathogens before spillover into humans. Therefore, WBE is necessary in locations where there is a risk of spillover into humans before disease outbreak occurs. Specifically, surveillance of pathogens, especially zoonotic ones, in wastewater from livestock farms, wet markets, and their surrounding areas is particularly important.

Livestock farms are reservoirs and sites of amplification of infectious agents, including zoonotic pathogens. Studies have shown that about 77% of livestock pathogens can infect multiple host species, including wildlife and humans (appendix).² Furthermore, livestock markets and wet markets serve as hubs for pathogens and have been linked to the emergence of different epidemics, pandemics (eg, severe acute respiratory syndrome, COVID-19), and important foodborne-disease outbreaks (appendix).³ Livestock farms and wet markets are important pathogen spillover sites and current disease surveillance of them is insufficient. Wastewater from these settings contain microbes from various animals and diverse environment. Sampling of this wastewater for testing or archival purposes before further purification, or discharge into municipal sewers or rivers is essential to support large-scale implementation of WBE.

The potential sources of future epidemics or pandemics include viruses, bacteria, fungi, and parasites. Bacteria account for 54%, and viruses for 25%, of the 400 emerging infectious disease events recorded since 1940; outbreaks caused by protozoa (11%) and fungi (6%) are less common.⁴ Although still rapidly evolving, current untargeted approaches (ie, metagenomic and metatranscriptomic sequencing) can already provide holistic insights into the microbial communities in wastewater systems.⁵ In practice, important pathogens can be further detected by combining targeted (eg, quantitative PCR, amplicon sequencing) and semitargeted (ie, specific probe-based enrichment) methods (appendix). The data generated by these methods could be used to identify complex pathogen genetic evolution, population structure, and novel pathogen identification. Therefore, WBE in livestock farms and wet markets is particularly important for detecting early warning signs and origin tracing of emerging and re-emerging diseases.

The surveillance of wastewater pathogens in animal environments with high amounts of human activity can provide early warning signs and enhance the traceability of infectious diseases, which could accelerate the mitigation of public health risks associated with zoonotic pathogens. In conclusion, surveillance of wastewater pathogens under the One Health framework is essential for the prevention of, and a quick and early response to, the future pandemics.

For more on One Health see https://www.who.int/health-topics/one-health#tab=tab_1

For more on way of monitoring COVID-19 outbreaks see https://www.arcgis.com/apps/dashboards/c778145ea5bb4daeb58d31afee389082

We declare no competing interests. This work was supported by the Young Top-Notch Talents Foundation of Henan Agricultural University.