Comparison between quantitative real-time reverse transcription PCR results for norovirus in oysters and self-reported gastroenteric illness in restaurant customers.
Norovirus is the principal agent of bivalve shellfish-associated gastroenteric illness worldwide. Numerous studies using PCR have demonstrated norovirus contamination in a significant proportion of both oyster and other bivalve shellfish production areas and ready-to-eat products. By comparison, the number of epidemiologically confirmed shellfish-associated outbreaks is relatively low. This study attempts to compare norovirus RNA detection in Pacific oysters (Crassostrea gigas) by quantitative real-time reverse transcription PCR (RT-PCR) and human health risk. Self-reported customer complaints of illness in a restaurant setting (screened for credible norovirus symptoms) were compared with presence and levels of norovirus as determined by real-time RT-PCR for the batch of oysters consumed. No illness was reported for batches consistently negative for norovirus by real-time RT-PCR. However, norovirus was detected in some batches for which no illness was reported. Overall presence or absence of norovirus showed a significant association with illness complaints. In addition, the batch with the highest norovirus RNA levels also resulted in the highest rate of reported illness, suggesting a linkage between virus RNA levels and health risks. This study suggests that detection of high levels of norovirus RNA in oysters is indicative of a significantly elevated health risk. However, illness may not necessarily be reported after detection of norovirus RNA at low levels.
Lowther
James A
JA
Centre for Environment, Fisheries and Aquaculture Science, European Community Reference Laboratory for Monitoring Bacteriological and Viral Contamination of Bivalve Molluscs, Weymouth DT4 8UB, UK. james.lowther@cefas.co.uk
Avant
Justin M
JM
Gizynski
Krzysztof
K
Rangdale
Rachel E
RE
Lees
David N
DN
D000818:Animals; D017250:Caliciviridae Infections / Q000453:epidemiology / Q000821:virology; D003257:Consumer Product Safety; D049896:Crassostrea / Q000382:microbiology*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005759:Gastroenteritis / Q000453:epidemiology / Q000821:virology; D006801:Humans; D029322:Norovirus / Q000302:isolation & purification*; D012367:RNA, Viral / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012680:Sensitivity and Specificity; D012758:Shellfish / Q000382:microbiology*; D019562:Viral Load
D012367:RNA, Viral