Key result
Tap water consumption linked to ~36-fold greater risk of norovirus gastroenteritis symptoms.
Why the study?
An unusual increase of gastroenteritis cases occurred in August 2015 in a touristic district in Kassandra peninsula, Chalkidiki, Northern Greece, prompting an investigation.
Does tap water consumption increase the risk of developing symptoms of gastroenteritis in individuals during the outbreak?
Case-Control (n=91)
No
Does tap water consumption increase the risk of developing symptoms of gastroenteritis in individuals during the outbreak?
Odds Ratio: 36.9
p-value: p=0.018
The study identified tap water consumption as the likely source of a large norovirus outbreak in Greece involving unusual strains GI.P2_GI.2 and GII.P16_GII.13.
Supports tap water investigation in norovirus outbreaks; leaves open causal role and need for confirmatory studies before practice change.
Noroviruses, along with rotaviruses, are among the leading causes of gastroenteritis worldwide and novel strains are periodically emerging. In August 2015, an unusual increase of gastroenteritis cases occurred in a touristic district in Kassandra peninsula, Chalkidiki, Northern Greece. Seven stool specimens from cases were tested positive for norovirus. Molecular investigation and phylogenetic analysis identified that there was co-circulation of norovirus GI.P2_GI.2 and the recombinant strain GII.P16_GII.13. A 1:1 case-control study conducted and showed that tap water consumption significantly associated with developing symptoms of gastroenteritis (odds ratio = 36.9, P = 0.018). The results of the epidemiological investigation, the co-circulation of two different norovirus strains, the information of a pipeline breakage at the water supply system before the onset of cases, and reports on flooded wells and sewage overflow, indicated the possibility of water contamination by sewage during the pipeline breakage leading to a large outbreak with a peak at 10 August and a possible secondary person-to-person transmission after the 16th of August. Norovirus GI.P2_GI.2 strains are rarely reported in Europe, while it is the first time that infection from the recombinant strain GII.P16_GII.13 is recorded in Greece.
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Tryfinopoulou et al. (2019) conducted a case-control in Norovirus gastroenteritis (n=91). Tap water consumption vs. No tap water consumption was evaluated on Developing symptoms of gastroenteritis (OR 36.9, p=0.018). Tap water consumption was significantly associated with developing symptoms of norovirus gastroenteritis during a 2015 outbreak in Chalkidiki, Greece (OR 36.9, p=0.018).
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