Norovirus in Bottled Water Associated with Gastroenteritis Outbreak, Spain, 2016

Area of Science:

• Environmental microbiology
• Public health
• Infectious disease epidemiology

Background:

• Gastrointestinal illness outbreaks pose significant public health challenges.
• Norovirus is a leading cause of gastroenteritis outbreaks globally.
• Identifying transmission sources is crucial for outbreak control.

Purpose of the Study:

• To investigate the cause of a large gastrointestinal illness outbreak in Catalonia.
• To identify the specific pathogen and potential contamination source.
• To quantify viral levels in suspected sources.

Main Methods:

• Case investigation and epidemiological analysis of 4,136 reported illnesses.
• Environmental sampling of office water coolers in affected areas.
• Norovirus genotyping (genotypes I and II) using molecular methods.
• Quantitative viral titer estimation using infectious viral titer assays.

Main Results:

• High levels of norovirus genotypes I and II were detected in office water coolers.
• Infectious viral titers were estimated at 33-49 genome copies/L for genotype I and 327-660 genome copies/L for genotype II.
• The findings strongly implicate contaminated water coolers as the source of the outbreak.

Conclusions:

• Office water coolers can serve as a significant vehicle for norovirus transmission during outbreaks.
• Effective water source management and hygiene practices are essential to prevent widespread gastrointestinal illness.
• This study highlights the importance of environmental testing in identifying outbreak sources.