A Multistate Outbreak of Oyster-Associated Gastroenteritis: Implications for Interstate Tracing of Contaminated Shellfish

Abstract

In November 1993, clusters of gastroenteritis in six states following oyster consumption were investigated to identify common features, and stool samples were obtained to identify a pathogen. Efforts were made to account for all potentially contaminated oysters using harvest tags and the interstate recall system. Consumption of oysters was associated with illness in 10 clusters; no other food was implicated. A Norwalk-like virus was detected by electron microscopy in 9 of 18 samples and by reverse transcription-polymerase chain reaction in 20 of 26 samples from 6 clusters. Nucleotide sequences of a 123-bp fragment from all specimens were identical, consistent with a common source outbreak. Implicated oysters were harvested from the Louisiana coast between 9 and 12 November. Although some were recalled and destroyed, most oysters harvested from the area during this time remain unaccounted for. Current regulations and commercial practices need to be revised to permit thorough tracing and recall of contaminated oysters and to improve control of future epidemics.

Broadly Reactive and Highly Sensitive Assay for Norwalk-Like Viruses Based on Real-Time Quantitative Reverse Transcription-PCR

“…NLV infections often result from ingesting contaminated food (14,30), such as oysters (4,8) and water (3,33), or by person-to-person transmission in semiclosed communities, such as hospitals (35), schools (20), nursing homes (18), and cruise ships (12).…”

International Collaborative Study To Compare Reverse Transcriptase PCR Assays for Detection and Genotyping of Noroviruses

“…Epidemiological investigations of outbreaks have shown that the most important modes of transmission are person-to-person contacts and contaminated food and water (20,31). Multistate and global outbreaks linked to the distribution of contaminated foods and water have been reported (4,6,14,45). Moreover, the emergence of a common strain with global distribution has raised important questions on the likelihood of massive food-borne introduction of new NLV strains (43,51).…”

Oceans and human health: Emerging public health risks in the marine environment

“…Refrigeration paradoxically increases the pathogens' geographic range, permitting transport of apparently healthy seafood to many geographic areas, thus extending and prolonging outbreaks. Inadequate procedures for tracing and recall of contaminated seafood also serve to extend outbreaks (Dowell et al, 1995;Sugieda et al, 1996).…”