Steaming oysters does not prevent Norwalk-like gastroenteritis.
OBJECTIVE
To determine whether steaming oysters prevents gastroenteritis caused by small round structured (Norwalk-like) viruses and to identify risk factors for illness.


METHODS
The authors interviewed all 48 people who ate oysters at two church suppers that were followed by outbreaks of gastroenteritis from a Norwalk-like virus. Data were collected on demographics, clinical illness, number of oysters eaten, and the extent to which they were cooked.


RESULTS
Among the 48 persons, the attack rate was 56%. The risk of illness increased with the number of oysters eaten (chi-square for trend = 5.7, P = 0.02). There was no decrease in attack rates among persons who ate oysters that were better done (chi-square for trend = 1.1, P = 0.29).


CONCLUSIONS
In these outbreaks, the risk of illness increased with the number of oysters eaten. Steaming oysters did not appear to prevent illness, suggesting that steaming may not be adequate to inactivate small round structured viruses. Public health messages that have emphasized the role of raw shellfish in the transmission of enteric viruses should be altered to increase the public's awareness that eating steamed oysters may also pose health risks.
Kirkland
K B
KB
Epidemiology Program Office, Centers for Disease Control and Prevention (CDC), Atlanta, USA.
Meriwether
R A
RA
Leiss
J K
JK
Mac Kenzie
W R
WR
D000818:Animals; D017250:Caliciviridae Infections / Q000517:prevention & control* / Q000821:virology*; D016009:Chi-Square Distribution; D003296:Cooking / Q000379:methods*; D004196:Disease Outbreaks; D005500:Follow-Up Studies; D005759:Gastroenteritis / Q000517:prevention & control* / Q000821:virology*; D006801:Humans; D009657:North Carolina; D009663:Norwalk virus; D010125:Ostreidae / Q000821:virology*; D012307:Risk Factors; D017747:Seafood / Q000821:virology*; D011795:Surveys and Questionnaires