Critical Review on the Public Health Impact of Norovirus Contamination in Shellfish and the Environment: A UK Perspective.
We review the risk of norovirus (NoV) infection to the human population from consumption of contaminated shellfish. From a UK perspective, risk is apportioned for different vectors of NoV infection within the population. NoV spreads mainly by person-to-person contact or via unsanitary food handling. NoV also enters the coastal zone via wastewater discharges resulting in contamination of shellfish waters. Typically, NoV persists in the marine environment for several days, with its presence strongly linked to human population density, wastewater discharge rate, and efficacy of wastewater treatment. Shellfish bioaccumulate NoV and current post-harvest depuration is inefficient in its removal. While NoV can be inactivated by cooking (e.g. mussels), consumption of contaminated raw shellfish (e.g. oysters) represents a risk to human health. Consumption of contaminated food accounts for 3-11% of NoV cases in the UK (~74,000 cases/year), of which 16% are attributable to oyster consumption (11,800 cases/year). However, environmental and human factors influencing NoV infectivity remain poorly understood. Lack of standard methods for accurate quantification of infective and non-infective (damaged) NoV particles represent a major barrier, hampering identification of an appropriate lower NoV contamination limit for shellfish. Future management strategies may include shellfish quality assessment (at point of harvest or at point of supply) or harvesting controls. However, poor understanding of NoV inactivation in shellfish and the environment currently limits accurate apportionment and risk assessment for NoV and hence the identification of appropriate shellfish or environmental quality standards.
Centre for Applied Marine Sciences, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, UK.
Francis
F
Hassard
Natural Resources Wales, Ty Cambria, Cardiff, CF24 0TP, UK.
Jasmine H
JH
Sharp
School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
Helen
H
Taft
Centre for Applied Marine Sciences, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, UK.
Lewis
L
LeVay
NIHR Health Protection Research Unit in Gastrointestinal Infections, University of Liverpool, Liverpool, L69 3GL, UK.
John P
JP
Harris
School of Biological Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
James E
JE
McDonald
Centre for Applied Marine Sciences, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, UK.
Karen
K
Tuson
Bangor Mussel Producers Ltd., Victoria House, Plas Llwyd Terrace, Bangor, Gwynedd, LL57 1UB, UK.
James
J
Wilson
School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
David L
DL
Jones
Centre for Applied Marine Sciences, School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey, LL59 5AB, UK. s.malham@bangor.ac.uk.
Shelagh K
SK
Malham
D000818:Animals; D017250:Caliciviridae Infections / Q000821:virology*; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D029322:Norovirus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D011634:Public Health; D012758:Shellfish / Q000821:virology*; D006113:United Kingdom; D014871:Water Microbiology
Aquaculture; Food safety; Norovirus; Norwalk; Oyster; Shellfish