Foodborne viral outbreaks associated with frozen produce

Abstract

Over the past decade, frozen fruits have been a major vehicle of foodborne illnesses mainly attributed to norovirus (NoV) and hepatitis A virus (HAV) infections. Fresh produce may acquire viral contamination by direct contact with contaminated surface, water or hands, and is then frozen without undergoing proper decontamination. Due to their structural integrity, foodborne viruses are able to withstand hostile conditions such as desiccation and freezing, and endure for a long period of time without losing their infectivity. Additionally, these foods are often consumed raw or undercooked, which increases the risk of infection. Herein, we searched published literature and databases of reported outbreaks as well as the databases of news articles for the viral outbreaks associated with the consumption of frozen produce between January 2008 and December 2018; recorded the worldwide distribution of these outbreaks; and analysed the implication of consumption of different types of contaminated frozen food. In addition, we have briefly discussed the factors that contribute to an increased risk of foodborne viral infection following the consumption of frozen produce. Our results revealed that frozen fruits, especially berries and pomegranate arils, contributed to the majority of the outbreaks, and that most outbreaks were reported in industrialised countries.

Keywords: Frozen fruit; Hepatitis A virus; Norovirus; Outbreak.

Fig. 1.

(a) The yearly distribution of the number of the reported viral outbreaks associated with frozen produce. (b) The yearly distribution of the number of the reported cases associated with HAV and NoV infections from frozen produce. Data are from the PAIFOD database and are shown for both NoV (blue) HAV (red).

Fig. 2.

Geographical distribution of reported viral outbreaks linked to frozen fruits. Each outbreak in the PAIFOD database was mapped onto its country of origin. Points were assigned a random position within their country of origin to allow visualisation on the map. The size of each point corresponds to the number of cases in each outbreak. Blue points correspond to NoV and red points correspond to H A V.

Fig. 3.

Type of frozen fruit implicated in viral outbreaks from the published sources. (a) Total number of outbreaks. (b) Total cases of illnesses. Data from the PAIFOD database were curated into one of five commonly occurring categories. Data are shown for both Norovirus (blue) and Hepatitis A (red).

Fig. 4.

A map showing the location of newspaper articles from the GPHIN database describing outbreaks of Hepatitis A (a) and Norovirus (b). Only those articles describing a quantitative number of people becoming sick are included. The colour of the point corresponds to the number of people reported sick in each article.