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Are viruses among the leading causes of bathing-related infectious outbreaks?

Jan 19, 2022

A review of an EU legislation, the Bathing Water Directive 2006/7/EC3 (BWD), is currently underway to examine how the Directive has contributed to protecting public health and clean waters, complementing national security efforts.

We spoke to one expert on faecal water contamination indicators, Prof. Dr. Anicet R. Blanch, from the Dept. of Genetics, Microbiology, and Statistics at the University of Barcelona about the review of the present Directive, proposed by the Commission in December 2019 within the European Green Deal for the European Union (EU) and its citizens, as a new growth strategy to protect, conserve and enhance the EU’s natural capital, and protect the health and well-being of citizens from environment-related risks and impacts.
This deal provided a roadmap with actions to boost resource efficiency, moving to a clean and circular economy, restoring biodiversity, and reducing pollution.
One of its eight policy areas focuses on pollution reduction and the adoption of an EU action plan to achieve the ambition of zero pollution in air, water and soil.

Does the open (BWD) review of the BWD respond to emerging health concerns, specifically viruses, and does it meet the level of affordable health protection related to “the latest scientific evidence and health recommendations issued by the WHO (viruses, cyanobacteria)”?

In my opinion, the combined evaluation roadmap / Inception Impact Assessment by the European Commission makes a good analysis of the current situation, problem, and possible improvements in the new BWD. Not only the latest scientific evidence, progress, and innovation have been considered, but also the recommendations issued by the WHO and those by the different health agencies of the Member States that have contributed with their gained experience from implementing the present BWD during all these years. Among these scientific evidences, the problems of microbiological quality derived from virus-related outbreaks and cyanobacteria are correctly addressed. It is also very well indicated that the current Directive may not adequately address new health concerns such as virus outbreaks, and therefore improvements should be made, in that issue, to the new proposed BWD.

I think that the consultation period opened by the European Commission until January 20, 2022, is a very good opportunity for all citizens, responsible staff on health and quality of bathing water, stakeholders, and health authorities bodies to make contributions from their experiences for an improvement of the future new BWD. I encourage the participation of those interested in this public consultation.

What actions could increase health problems related to the discharge of raw or treated wastewater into water bodies in the future?

Current trends, such as the increasing concentration of population in large urban agglomerations, climate change, which in Europe may lead to heavy rainfall with sudden episodes of wastewater leakage, deteriorating surface water quality, aging of existing infrastructures, and emerging pathogens, indicate that health problems related to the discharge of raw or treated wastewater into water bodies will increase in the future.

Are viruses among the leading causes of bathing-related infectious outbreaks?

There is growing evidence that, even in the European Union where the quality of bathing water has been very well monitored in recent decades, probably due to this increased surveillance and reporting, bathing-related infectious outbreaks have been detected, with viruses being the second leading cause.
A recent peer-review meta-analysis involving 18 EU countries, with a total of 87 investigations over 35 years, showed that viruses were detected in 52% of all samples in which waterborne organisms of public health concern were found.

What indicator of faecal contamination is recommended for testing to provide bathing water consumers with an improvement on the safety of use?

It is now well known and widely accepted that faecal bacteria indicators (FBI) used to define microbiological water quality are not suitable for predicting the presence of viruses.
Coliphages (bacteriophages infecting E. coli), mostly somatic coliphages, are increasingly accepted as having value as viral indicators and are being applied in many water quality guidelines and regulations in many countries, including the EU (for example in drinking water monitoring and in the validation of treatments for water reuse). Also, the US Environmental Protection Agency conducted an extensive review of coliphages as viral indicators of recreational water quality (US-EPA. 2015. Recreational Water. Review of coliphages as potential fecal contamination indicators for environmental water quality. EPA 820-R-15-098).
Subsequently, a group of experts convened by US EPA agreed that coliphages are useful for assessing surface water quality because they exhibit numerous desirable indicator characteristics (US-EPA 2016.Coliphage experts workshop: discussion and findings. EPA 823-f-16-001).

What are the favourable characteristics of somatic coliphages for testing faecal contamination in bathing (or recreational) waters?

They have suitable characteristics as their concentrations in wastewater are not seasonal and do not show geographical differences. It should also be noted that concentrations in bathing water are of the same order of magnitude as those of E. coli. Still, available information indicates that once released into water bodies, they behave similarly to viruses in terms of decomposition, with a longer persistence than FIBs. This difference increases in dry and warm conditions.

Do you think the practice of testing coliphages in water safety monitoring laboratories in Europe is widespread? Are there standardized methods?

ISO standardized methods for quantifying coliphages in water samples are available for many years. These methods have even been used with very good operability in bathing water in European research programs. In the project report “Bacteriophages in bathing waters: A feasibility study on the development of a method based on bacteriophages for the determination of microbiological quality of bathing waters” published by the EU Directorate General ΧΠΠΠ – Science, Research and Development (, these standardized methods are applied and described in detail. Coliphages, as viral indicators, prove to be a very adequate microbial parametric complement to E.coli monitoring that helps us advance in better control of the microbiological quality of bathing water.


In Bluephage’s opinion, the inclusion of coliphages as viral indicators in bathing water quality criteria deserves consideration.
Rapid and feasible methods for detecting somatic coliphages in water are now emerging, providing a highly likely scenario of somatic coliphage detection within a few hours.
This is a critical aspect in a context where climate change will accelerate the urgency of decision-making to allow access to recreational waters.

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