Cholera Bacteria Found in City Sewage Systems

Jenn Hoskins
2nd August, 2024

Cholera Bacteria Found in City Sewage Systems

Image Source: Natural Science News, 2024

Key Findings

  • Researchers found Vibrio cholerae in a wastewater treatment plant in Copenhagen, Denmark, where cholera hasn't been reported locally for over a century
  • Despite its very low abundance, they recovered a near-complete genome of V. cholerae from 115 sewage samples collected over eight years
  • The strain found lacks the gene for cholera toxin production, suggesting it may not pose an immediate public health risk
The presence of Vibrio cholerae, the bacterium responsible for cholera, has been detected at a wastewater treatment plant in Copenhagen, Denmark. This discovery, made by researchers at the Technical University of Denmark, is notable because Denmark has not reported any environmental or locally transmitted clinical cases of V. cholerae in over a century[1]. Despite its low abundance, the team managed to recover a near-complete genome from 115 metagenomic sewage samples collected over the past eight years. This finding underscores the importance and challenges of wastewater-based pathogen surveillance. Wastewater-based epidemiology (WBE) involves analyzing sewage to monitor public health. This approach is particularly useful for tracking antimicrobial resistance (AMR) and viral diversity. A previous study demonstrated the effectiveness of using metagenomic analysis of untreated sewage to characterize bacterial resistomes from various global sites, revealing significant regional differences in AMR gene abundance and diversity[2]. Another study highlighted the potential of next-generation sequencing (NGS) techniques for identifying viruses in urban sewage, emphasizing the complexity of such analyses and the need for efficient virus concentration methods[3]. The recent study in Copenhagen adds to this body of work by focusing on a specific bacterial pathogen, V. cholerae. The researchers faced significant challenges due to the bacterium's extremely low relative abundance—one V. cholerae read out of 500,000 sequenced reads. Routine screening methods failed to detect the bacterium, highlighting the sensitivity required for effective pathogen surveillance. The recovered genome lacks the gene responsible for cholera toxin production, suggesting that this strain may not pose an immediate public health risk. The study's methodology involved collecting and analyzing metagenomic data from sewage samples over an extended period. This long-term approach allowed the researchers to identify a persistent presence of V. cholerae, despite its low abundance. The findings illustrate how metagenomic analysis can uncover hidden microbial communities and pathogens that traditional methods might miss. The implications of this research are significant. It demonstrates that wastewater can serve as a valuable resource for monitoring pathogens, even in regions where certain diseases have not been reported for decades. This aligns with earlier findings that urban sewage, representing the excreta of thousands of inhabitants, is a representative sample for epidemiological surveillance[3]. The study also emphasizes the importance of continuous monitoring to detect and understand the presence of potentially pathogenic bacteria, even those not currently causing disease outbreaks. In summary, the discovery of V. cholerae in Copenhagen's wastewater highlights the effectiveness of metagenomic analysis for pathogen surveillance. This approach complements previous studies on AMR and viral diversity in sewage, showcasing the potential of wastewater-based epidemiology to provide valuable public health insights. The research underscores the need for sensitive and continuous monitoring methods to detect low-abundance pathogens and improve our understanding of microbial communities in urban environments.

EnvironmentHealthMarine Biology

References

Main Study

1) Discovery of Vibrio cholerae in Urban Sewage in Copenhagen, Denmark

Published 31st July, 2024

https://doi.org/10.1007/s00248-024-02419-7

Related Studies

2) Global monitoring of antimicrobial resistance based on metagenomics analyses of urban sewage.

https://doi.org/10.1038/s41467-019-08853-3

3) Metagenomics for the study of viruses in urban sewage as a tool for public health surveillance.

https://doi.org/10.1016/j.scitotenv.2017.08.249


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