# Investigation of the presence of human adenovirus, norovirus, and rotavirus in tap water in Marrakech, Morocco

## TL;DR

This study found high levels of human adenovirus and other viruses in tap water in Marrakech, highlighting the need for better water monitoring and treatment to protect public health.

## Contribution

This is the first study to investigate enteric viruses in tap water in Marrakech, Morocco, providing critical baseline data for the region.

## Key findings

- Human adenovirus was detected in 92.15% of tap water samples.
- Human norovirus genogroup II and group A rotavirus were also frequently detected.
- Human norovirus genogroup I was not found in any samples.

## Abstract

Given the significant role played by human pathogenic viruses in causing waterborne diseases, the necessity of monitoring viral contamination in drinking water is paramount for public health. The prevalence of enteric viruses in drinking water remains under-researched in Morocco, with a paucity of data on the issue. The present study, therefore, sought to assess the presence of enteric viruses, namely, human adenovirus (HAdV), human norovirus genogroup I (HNoV-GI) and genogroup II (HNoV-GII), and group A rotavirus (RVA) in tap water in Marrakech. A total of 102 tap water samples were collected, with virus concentration carried out using an internally validated method based on electronegative membranes. The application of quantitative PCR and reverse transcription-quantitative PCR techniques enabled the detection of HAdV in 92.15% of the samples, HNoV-GII in 48.03%, and RVA in 43.13%. It is noteworthy that HNoV-GI was not detected in any of the samples. The results were confirmed by agarose gel electrophoresis. This study is the first of its kind in the region, providing valuable insights into viral contamination in drinking water in Marrakech. In conclusion, the high prevalence of enteric viruses in tap water underscores the need for improved monitoring and more effective water treatment in Marrakech. These findings highlight the importance of prioritizing waterborne virus surveillance to protect public health, with further research needed to investigate viral integrity and infectivity to assess the real risk encountered by consumers.

This study highlights the value of virological monitoring of drinking water as a complementary tool to understand the circulation of enteric viruses in the community. As the first investigation of its kind in Marrakech, it provides essential baseline data in a context where such information is scarce in Morocco. The high prevalence of human adenovirus (92.15%) and the detection of human norovirus genogroup II and group A rotavirus underscore potential public health risks, especially for vulnerable populations. These findings reveal the limitations of relying solely on bacteriological indicators and emphasize the need to integrate routine viral surveillance into water quality monitoring programs. The results also provide scientific evidence to improve treatment and disinfection processes and to support further research on the infectivity of detected viruses.