Publication Abstract

Human enteric viruses in oysters causing a large outbreak of human foodborne infection in 1996/97

B.F. Christensen, D.N. Lees, K. Henshilwood, T. Bjergskov and J. Green

During the New Year of 1996/97, more than 350 persons in Denmark became ill from consumption of imported oysters. The main symptoms were vomiting, diarrhea, abdominal pain, and fever, commencing 12 to 48 hrs after consumption. In addition, a number of the diseased persons reported secondary symptoms, such as aching joints, skin numbness, and visual disturbances, commencing 24 h after onset of the primary symptoms. In general, recovery from both the primary and, in particular, the secondary symptoms was slow. Only 3/24 (12%) of the analyzed samples of infected oysters showed an F- coli level above the allowed regulatory limit. A small amount of domoic acid was found in 4/9 (443'0) of analyzed samples. Small round-structured virus (SRSV) and enterovirus were identified from both oyster and fecal samples, using RT-PCR. Enterovirus isolated from individual fecal samples showed sequence identity of 3 PCR amplicons, suggesting a common source of infection. The identity of the enterovirus is still under investigation. The characteristic clinical symptoms and RT-PCR results implicate SRSVs as the cause of the primary symptoms. However, the cause of the secondary symptoms is currently unclear. Although the detection of enterovirus in both fecal samples and oysters is significant, the incubation period prior to onset of secondary symptoms was not typical of an enterovirus infection. The significance of the domoic acid in relation to the outbreak is unclear.

Reference:

B.F. Christensen, D.N. Lees, K. Henshilwood, T. Bjergskov and J. Green, 1999. Human enteric viruses in oysters causing a large outbreak of human foodborne infection in 1996/97. Journal of Shellfish Research, 17(5): 1633-1635.