Detection of Hepatitis A Virus and Norovirus in Different Food Categories: A 6-Year Survey in Italy

Norovirus GII.17 Caused Five Outbreaks Linked to Frozen Domestic Bilberries in Finland, 2019

In March 2019, the Finnish Institute for Health and Welfare and Finnish Food Authority started an outbreak investigation after a notification of food business operators' recall of frozen bilberries due to a norovirus finding. A retrospective search was conducted in the food and waterborne outbreak notification system to identify the notifications linked to norovirus and consumption of bilberries in January-March 2019. Five outbreaks were found in which norovirus GII or GII.17 had been detected in patient samples. A pooled retrospective cohort study was performed for those four in which a questionnaire study had been done. A case was defined as a person with diarrhoea or vomiting within 2 days after consuming a meal studied at one of the outbreak locations. Of 79 participants, 45 (57%) cases were identified. Persons that had consumed foods containing unheated bilberries were three times more likely to get ill than those who had not consumed them (RR 3.1, CI 95% 1.2-8.1, p = 0.02). Norovirus GII.17 was found in 16/17 patient samples sent for further typing. Identical norovirus GII.17 was detected in frozen Finnish bilberries and patient samples. At the berry packaging premises, signs of norovirus GII contamination were found in packaging lines. A new procedure for extracting viral nucleic acid from food and environmental samples was used during the outbreak investigation. Consumption of industrially packed frozen berries as heated would be one of the means to prevent norovirus infections.

Meta-analysis of the prevalence of norovirus and hepatitis a virus in berries

Norovirus (NoV) and hepatitis A virus (HAV) stand as the predominant agents associated with viral foodborne infections. Outbreaks have been documented to be caused by various types of food items, including fresh and/or frozen berries. Comprehensive data concerning crucial viral pathogens in berries remain limited and are not currently available in aggregate form. Consequently, the present study aimed to compile the existing information regarding the prevalence of NoV and HAV in this matrix. Records of foodborne viruses were systematically extracted from database repositories up to December 2022, adhering to PRISMA standards and were subjected to a multilevel random effect meta-analysis model to determine the mean occurrence rate of NoV and HAV. A high heterogeneity across studies was observed (I2 = 82 %), reflecting variations in the prevalence of sampling locations, years, berry types, and sample conditions, among other potential contributing factors. The prevalence of NoV and HAV in berries was calculated at 2.12 % (95 % CI 1.74-2.59 %), and no statistically differences were observed among the viral types or genogroup categories. However, it is important to clarify that this estimate should be taken with caution given the high heterogeneity. There was no discernible correlation between viral prevalence and any particular berry type. However, there was a temporal correlation observed with the year of sampling, revealing a significantly decreasing trend throughout the study period. A significant influence of the sample condition (fresh or frozen) was observed in relation to the prevalence of NoV GII and HAV. Overall higher viral prevalences were identified in berries originating from African countries as compared to those sourced from other continents. It was also noted that the prevalence of NoV GI was significantly higher in samples collected directly from farms compared to those obtained from retailers. The outcomes of this comprehensive meta-analysis propose that while viral contamination of berries is diminishing in more recent times, the prevalence remains substantial in certain African countries, having a significant risk for foodborne infections. It is imperative to implement intervention strategies in these regions to enhance product safety.

A systematic review and meta-analysis indicates a high risk of human noroviruses contamination in vegetable worldwide, with GI being the predominant genogroup

Human noroviruses (HuNoVs) are the most predominant viral agents of acute gastroenteritis. Vegetables are important vehicles of HuNoVs transmission. This study aimed to assess the HuNoVs prevalence in vegetables. We searched the Web of Science, Excerpta Medica Database, PubMed, and Cochrane databases until June 1, 2023. A total of 27 studies were included for the meta-analysis. Statistical analysis was conducted using Stata 14.0 software. This analysis showed that the pooled HuNoVs prevalence in vegetables was 7 % (95 % confidence interval (CI): 3-13) worldwide. The continent with largest number of studies was Europe, and the highest number of samples was lettuce. As revealed by the results of the subgroup meta-analysis, the prevalence of GI genogroup was the highest (3 %, 95 % CI: 1-7). A higher prevalence was seen in vegetables from farms (18 %, 95 % CI: 5-37), while only 4 % (95 % CI: 1-8) in retail. The HuNoVs prevalence of ready-to-eat vegetables and non-ready-to-eat vegetables was 2 % (95 % CI: 0-8) and 9 % (95 % CI: 3-16), respectively. The prevalence by quantitative real time RT-PCR was 8 % (95 % CI: 3-15) compared to 3 % (95 % CI: 0-13) by conventional RT-PCR. Furthermore, the HuNoVs prevalence in vegetables was 6 % (95 % CI: 1-14) in ISO pretreatment method and 8 % (95 % CI: 1-19) in non-ISO method, respectively. This study is helpful in comprehensively understanding the prevalence of HuNoVs contamination in vegetables worldwide.

Monitoring and Genotyping of Norovirus in Bivalve Molluscan Shellfish from Northern Italian Seas (2018-2020)

Norovirus (NoV) is an enteric virus with foodborne transmission. Bivalve shellfish are a main source of infections and outbreaks. In Italy a voluntary based monitoring plan to check the safety of bivalve shellfish was set up at provincial level. This study describes the occurrence and distribution of NoV in the Northern Adriatic Sea and in the Ligurian Sea. From October 2018 to September 2020, 807 bivalve shellfish samples (n = 205 oysters, n = 182 mussels, n = 348 clams, n = 72 other bivalve shellfish) were tested by One-Step Retrotranscription Real-time polymerase chain reaction for NoV GI and GII and quantified according to the ISO 15216-2:2013 and ISO 15216-1:2017. Positive samples were further analyzed to determine genotype by sequencing of the ORF1/ORF2 junction of the viral genome. A total of 126 samples were positive for NoV, mussels, and oysters had the highest probability of being positive and positive samples were found mainly in the colder season. Of these samples, 46% were NoV GII, 13% NoV GI, and 40% carried both genogroups. Thirty-seven samples were typeable (GI n = 12 and GII n = 25) with GI samples belonging to four genotypes and GII samples belonging to five genotypes. GII.3 genotype was the most prevalent, followed by GII.4, particularly Sydney 2012 subtype, a leading cause of infections worldwide, was found in three oysters' and three clams' samples. The phylogenetic analysis revealed a high heterogeneity among the species that are scattered in several clusters. Considering the low infectious dose the overall presence of NoV in edible shellfish, particular those to be eaten raw or undercooked, is moderately high. The presence of genotypes frequently involved in human infections strengthens the need for ongoing monitoring, which should be extended at national level.

Detection of Hepatitis A RNA, Hepatitis E RNA, Human Adenovirus F DNA, and Norovirus RNA in Fresh and Frozen Berry Products at Point of Retail in Ireland

Soft fruits are at particular risk of contamination with enteric viruses such as Hepatitis A virus (HAV), Hepatitis E Virus (HEV), Norovirus (NoV), Human Adenovirus (HAdV) and Sapovirus (SaV). The aim of this study was to investigate, for the first time, the presence of these biological agents in ready to eat (RTE) berries at point of retail in Ireland. A sampling strategy was designed in which RTE fresh and frozen strawberries and raspberries were purchased from five retailers between May and October 2018. Reverse Transcriptase Polymerase Chain Reaction (RT-qPCR) assays for HEV RNA, Nov RNA, SaV RNA, and human Adenovirus species F DNA (HAdV-F) were performed on 239 samples (25g portions). Viral nucleic acid was present in 6.7% (n = 16) of samples tested as follows: HAV RNA (n = 5), HAdV-F DNA (n = 5), HEV RNA (n = 3) and NoV GII RNA (n = 3). Sapovirus RNA was not detected in any product. No significant differences were found between berry type, fresh/frozen status, or supermarket source. This study suggests a risk that exists across all retail outlets however only low levels of nucleic acid ranging from 0 to 16 genome copies/g were present. Although these findings may reflect non-viable/non-infectious virus the continued provision of risk mitigation advice to consumers is warranted and further work is required to ensure control measures to reduce contamination are implemented and enforced.

Detection of Norovirus and Hepatitis A Virus in Strawberry and Green Leafy Vegetables by Using RT-qPCR in Egypt

There is an upward trend of consumption of organic fresh vegetables due to consumer demand for healthy foods without chemical additives. On the other hand, the number of food borne outbreaks associated with contaminated fresh produce has raised, being human norovirus genogroup I (GI), GII and hepatitis A virus (HAV) the most commonly reported causative agents. This study aimed to detect the presence of these viruses in green leafy vegetables (watercress, leek, coriander, and parsley) and strawberry using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Samples were collected from the Egyptian regions of Kalubia, Giza, and Mansoura. Overall HAV average occurrence in fresh strawberry was 48% with a mean concentration of 6.1 × 10³ GC/g; Also NoV GI overall average occurrence was 25% with a mean concentration of 9.7 × 10² genome copies (GC)/g, while NoV GII was 40% with a mean concentration of 2.4 × 10³ GC/g. For strawberry collected directly from Kalubia farms, neither HAV nor HNoV GI & GII were detected. In green leafy vegetable samples, the occurrence of HAV was 31.2% with a mean concentration of 9.2 × 10⁴ GC/g, while occurrence of NoV GI and NoV GII were 20% and 30% with a mean concentrations of 1.1 × 10⁴ and 2.03 × 10³ GC/g, respectively. In conclusion, the importance of a virus surveillance program for soft fruits and fresh vegetables is highlighted by the outcomes of this study. Our findings should help with the management and control of microbial concerns in fresh foods, reducing the danger of consuming contaminated foods.