Assessment of the Impact on Human Health of the Presence of Norovirus in Bivalve Molluscs: What Data Do We Miss?

Abstract

In the latest One Health ECDC EFSA technical report, Norovirus in fish and fishery products have been listed as the agent/food pair causing the highest number of strong-evidence outbreaks in the EU in 2019. This review aims to identify data gaps that must be filled in order to increase knowledge on Norovirus in bivalve molluscs, perform a risk assessment and rank the key mitigation strategies for this biological hazard, which is relevant to public health. Virologic determinations are not included in any of the food safety and process hygiene microbiologic criteria reflected in the current European regulations. In addition, the Escherichia coli-based indices of acceptable faecal contamination for primary production, as well as the food safety criteria, do not appear sufficient to indicate the extent of Norovirus contamination. The qualitative risk assessment data collected in this review suggests that bivalve molluscs present a high risk to human health for Norovirus only when consumed raw or when insufficiently cooked. On the contrary, the risk can be considered negligible when they are cooked at a high temperature, while information is still scarce for non-thermal treatments.

Use of Human Intestinal Enteroids to Evaluate Persistence of Infectious Human Norovirus in Seawater

“…some from GI, are more often implicated in foodborne or waterborne outbreaks (1)(2)(3)(4)(5). This difference might reflect variations in particle resistance to environmental conditions (1,7), but empirical data are lacking.…”

“…Human noroviruses are the major cause of viral gastroenteritis worldwide ( 1 ) and the most common cause of foodborne or waterborne outbreaks in Europe ( 2 ). Noroviruses spread through fecal–oral transmission, mainly person to person, but also spread through environmental contamination ( 1 ).…”

“…Food and drinks can be contaminated by infected food handlers and, during production, by human sewage spillover ( 3 ). When grown in contaminated seawater, filter-feeding shellfish bioaccumulate human noroviruses in their tissues ( 2 , 4 ). Shellfish, especially those eaten raw, are among the main foods involved in foodborne epidemics ( 2 , 5 ).…”

“…When grown in contaminated seawater, filter-feeding shellfish bioaccumulate human noroviruses in their tissues ( 2 , 4 ). Shellfish, especially those eaten raw, are among the main foods involved in foodborne epidemics ( 2 , 5 ).…”

“…Yet, for almost 50 years, the lack of a reproducible cell culture system impaired the direct assessment of human norovirus infectivity in environmental conditions. Hence, data used for risk assessment rely on molecular assays or surrogate viruses ( 2 ). Previously, we used a surrogate calicivirus, Tulane virus (TuV), to estimate the persistence of infectious human norovirus in shellfish ( 10 ).…”