Survival of noroviruses in food - a review

Noroviruses are recognized as an important cause of acute gastroenteritis in Summary humans. It is assumed that foodborne infections can occur. To estimate the possible health risk associated with the consumption of certain products data about survival time of these viruses in food must be provided. Furthermore, the impact of food specific intrinsic factors and technologies on the inactivation kinetics of noroviruses has to be examined. In this context available data were reviewed in the present work. At this time it is not possible to propagate human noroviruses in cell cultures. For this reason results were obtained from studies with closely related surrogate viruses like Feline Calicivirus which can be grown in cell culture. Also epidemiological examinations which were carried out after food-associated infections as well as infection studies with human volunteers are useful tools to assess survival time of noroviruses. Alternatively, molecularbiological methods for detection and quantitation of noroviruses can be used even though detection of virus RNA is not an evidence for the infectivity of virus particles. Altogether, results show that apart from heat treatment (> +70 degrees C) technological measures like freezing, freeze-thawing, cooling and acidification of food as well as chlorination of potable water are not sufficient procedures to inactivate these pathogens. The influence of other usual food preserving technologies like ripening, curing or smoking on the survival time and inactivation kinetics of norovirus and norovirus surrogates was not examined up to now. In conclusion, more detailed studies including other norovirus surrogates are recommended to provide a scientific basis for the risk assessment of certain food-processing technologies.