Raw oyster consumption and outbreaks of viral gastroenteritis in New Zealand: evidence for risk to the public's health

Citation
G. Simmons et al., Raw oyster consumption and outbreaks of viral gastroenteritis in New Zealand: evidence for risk to the public's health, AUS NZ J PU, 25(3), 2001, pp. 234-240
Citations number
33
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Public Health & Health Care Science
Journal title
AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH
ISSN journal
1326-0200 → ACNP
Volume
25
Issue
3
Year of publication
2001
Pages
234 - 240
Database
ISI
SICI code
1326-0200(200106)25:3<234:ROCAOO>2.0.ZU;2-3
Abstract
Objective: To investigate the relationship between consumption of raw Pacif ic half shell oysters and outbreaks of Norwalk-like virus (NLV) gastroenter itis in Auckland in the last third of 1999. Method: Ten outbreaks were investigated as retrospective cohorts using stan dardised questionnaires relating to food and drink exposures. Trace back of oysters and site inspections of implicated commercial growing areas were p erformed. Virological analyses compared oysters linked to outbreaks and fae cal samples from cases. Results: Eighty-six cases were identified, of whom 32 (37.2%) were confirme d NLV positive on faecal analysis. The summary risk estimate for illness am ong oyster consumers for all outbreaks was RR 8.23 (95% CI 4.55-14.90; p < 0.001) and in five of seven outbreaks permitting statistical analysis, the risk for those consuming raw oysters was greater than five-fold that of non -consumers. NLVs were identified in two batches of oysters from different g rowing areas, implicated in four outbreaks. In both the strain (Genogroup I I/3 'Mexico-like virus') from cases matched that in the oysters from the sa me harvest batch. Conclusion: The epidemiological and virological evidence implicates oysters as the source of a number of outbreaks of NLV gastroenteritis. This is the first time NLVs have been identified in commercially farmed Pacific oyster s in New Zealand. Sewage effluent from recreational boats was the likely so urce of faecal contamination of growing waters in one site. Implications: Combined use of virological and epidemiological methods have proved invaluable in investigating NLV outbreaks. Further research is neede d into enteric viral contamination of commercial oyster farms.