Oysters Worldwide Contaminated with Norovirus
Date: 14-Sep-05
Country: USA
Senior investigator Dr. Wilina W. L. Lim told Reuters Health that "it appears that oysters may be an important vehicle for introducing novel strains of norovirus."
Outbreaks of gastric illness caused by norovirus are often linked to eating oysters and contamination appears to be widespread, note Lim, at the Public Health Laboratory Center, Kowloon, and colleagues in the Journal of Medical Virology.
They found that 10.5 percent of 507 samples of oysters from 11 countries tested on arrival were positive for norovirus genetic material. In particular, oysters from six countries were contaminated, while those from the remaining five countries were not -- but the team does not say what those countries were.
A wide variety of virus strains was found, including two novel types.
"Given the popularity of consuming raw oysters in many countries, oysters may serve (as) a vehicle for the dissemination of new norovirus strains," Lim's group concludes.
Norovirus screening was also conducted following 13 outbreaks of oyster-associated gastroenteritis in hotels or restaurants in Hong Kong. Norovirus sequences were detected in at least one oyster in six outbreaks.
However, only in one outbreak was there a match between the strains isolated from patients and those found in the oysters.
SOURCE: Journal of Medical Virology, August 2005.