MOLECULAR EVIDENCE OF OYSTERS AS VEHICLE OF EMERGING NOROVIRUS GII.P17-GII.17
Abstract
Emerging GII.P17-GII.17 noroviruses have replaced the GII.4 Sydney 2012 variant as the dominating genotype in parts of Asia, while they have only been detected sporadically in other continents. The major reservoir(s) of... [ view full abstract ]
Emerging GII.P17-GII.17 noroviruses have replaced the GII.4 Sydney 2012 variant as the dominating genotype in parts of Asia, while they have only been detected sporadically in other continents. The major reservoir(s) of GII.17 that contribute to transmission are unknown but it has been suggested that oysters are common vehicles for transmission. In January/February 2016, several outbreaks of acute gastroenteritis (AGE) were reported in Denmark among groups of people after consumption of oysters at different dining locations.
An investigation was initiated to establish geography, attack rate and food exposure to determine a potential connection between the outbreaks, and to reveal the source(s) to stop the outbreaks. Patient stool samples and oyster samples from the suspected source were collected for norovirus testing by PCR and detected strains of norovirus were sequences from both sample types and aligned for homology.
58 out of 67 persons developed AGE after eating oysters served at 18 occasions at 8 restaurants and one private party. Sequencing of stool and food samples demonstrated two variants of the emerging GII.P17-GII.17 and molecular evidence of linkage between the norovirus in stools and oysters.
This study is among the first to establish a direct molecular link between a common food source and a series of AGE outbreaks caused by norovirus GII.17. It shows that oysters act as important vehicles for rapid spread of emerging noroviruses to distant geographical areas. Furthermore, we document that co-transmission with quasispecies of GII.P17-GII.17 might occur simultaneously; an important finding to consider in future molecular-epidemiological outbreak investigations.
Authors
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Lasse Dam Rasmussen
(Statens Serum Institut)
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Anna Charlotte Schultz
(The National Food Institute, Technical University of Denmark)
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Katrine Uhrbrand
(The National Food Institute, Technical University of Denmark)
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Tenna Jensen
(Danish veterinary and food administration)
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Thea Kølsen Fischer
(Statens Serum Institut)
Topic Areas
Epidemiology , Outbreak studies
Session
OS-07 » Distribution and detection of human enteric viruses in shellfish (11:10 - Tuesday, 16th May, Bailey Allen 2)