n engl j med
new england journal
Gastroenteritis Associated with Alaskan Oysters
Joseph B. McLaughlin, M.D., M.P.H., Angelo DePaola, Ph.D.,
Cheryl A. Bopp, M.S., Karen A. Martinek, R.N., M.P.H., Nancy P. Napolilli, B.S.,
Christine G. Allison, B.S., Shelley L. Murray, B.S., Eric C. Thompson, B.S.,
Michele M. Bird, M.S., and John P. Middaugh, M.D.
From the Division of Public Health, Alaska
Department of Health and Social Services
(J.B.M., K.A.M., J.P.M.); and the Alaska De-
partment of Environmental Conservation
(N.P.N., C.G.A., S.L.M.) — both in Anchor-
age; the Food and Drug Administration,
Gulf Coast Seafood Laboratory, Dauphin
Island, Ala. (A.D.); the Centers for Disease
Control and Prevention, National Center
for Infectious Diseases, Atlanta (C.A.B.,
M.M.B.); and the Washington State De-
partment of Health Public Health Labora-
tories, Shoreline (E.C.T.). Address reprint
requests to Dr. McLaughlin at the Division
of Public Health, Alaska Department of
Health and Social Services, 3601 C St.,
Suite 540, Anchorage, AK 99503, or at
N Engl J Med 2005;353:1463-70.
Copyright © 2005 Massachusetts Medical Society.
the leading cause of seafood-associated gastroenteritis in the
United States, typically is associated with the consumption of raw oysters gathered
from warm-water estuaries. We describe a recognized outbreak of
infection associated with the consumption of seafood from Alaska.
After we received reports of the occurrence of gastroenteritis on a cruise ship, we con-
ducted a retrospective cohort study among passengers, as well as active surveillance
throughout Alaska to identify additional cases, and an environmental study to identify
and contributors to the outbreak.
Of 189 passengers, 132 (70 percent) were interviewed; 22 of the interviewees (17 per-
cent) met our case definition of gastroenteritis. In our multiple logistic-regression analy-
sis, consumption of raw oysters was the only significant predictor of illness; the attack
rate among people who consumed oysters was 29 percent. Active surveillance identi-
fied a total of 62 patients with gastroenteritis.
serotype O6:K18 was
isolated from the majority of patients tested and from environmental samples of oys-
ters. Patterns on pulsed-field gel electrophoresis were highly related across clinical and
oyster isolates. All oysters associated with the outbreak were harvested when mean daily
water temperatures exceeded 15.0°C (the theorized threshold for the risk of
illness from the consumption of raw oysters). Since 1997, mean water
temperatures in July and August at the implicated oyster farm increased 0.21°C per year
(P<0.001 by linear regression); 2004 was the only year during which mean daily tem-
peratures in July and August at the shellfish farm did not drop below 15.0°C.