Norovirus contamination of shellfish from high sanitary quality production areas of Portugal

• Autor(a) principal: Mesquita, João Rodrigo Gonçalves Goiana
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/2036

This report aims to: i) provide information on norovirus presence in shellfish from Portugal allowing for a contribution in the risk assessment of virus-related shellfish-borne hazards to the Portuguese bivalve mollusk consumers; ii) screen the North and Central Portugal shellfish beds for the presence of human norovirus in order to characterize mollusk production areas for viral hazards; and iii) evaluate the efficacy of European Regulations on microbiological criteria for bivalve mollusks in Portugal. Between March 2008 and February 2009, a total of 2030 bivalve mollusks were collected from 10 harvesting areas of the North and Centre of Portugal and organized by species and collection sites into 49 batches. The North region collection sites included Minho river estuary, Carreço, Lima river estuary, Cávado river and Douro river estuary. The Center region collection sites included Aguda, Torreira, São Jacinto bay, Costa Nova and Figueira da Foz. All batches were analyzed for Escherichia coli (ISO 16649-3), and tested for noroviruses. All amplified products were sequenced and phylogenetic analysis was performed. The correlation between the official area classification based on the fecal indicator E. coli and the presence of norovirus was evaluated. Norovirus was detected in 14 (41%) of the 34 batches from the North region collection sites, and 4 (26%) of the 15 Center region collection sites batches, revealing for the first time the presence of this virus in bivalve mollusk shellfish from Portugal. Nucleotide sequencing of the RT-PCR products demonstrated that all isolates were identical and belonged to genotype GII.4 2006b. No statistically significant relationship was found between the presence of norovirus and the E. coli levels. Two of the eight batches that were classified as “A class” harvesting areas were positive for norovirus. The fact that two “A class” batches were norovirus positive can represent a potentially serious risk to Public Health, a hazard never before considered in Portugal, since these batches in these conditions are legally allowed for direct consumption and therefore able to be introduced in the food chain with norovirus GII.4 2006b, a strain that has been predominant at a global scale for the past three years (Kanerva et al., 2009; Verhoef et al., 2008) and recently found to be circulating in Portugal (Mesquita & Nascimento, 2009).