Published Date: 1999-09-07 23:50:00
Subject: PRO> E. coli, toxigenic, waterborne - USA (Washington)(02)
Archive Number: 19990907.1560
E. COLI, TOXIGENIC, WATERBORNE - USA (WASHINGTON) (02)
******************************************************
A ProMED post
<http://www.healthnet.org/programs/promed.html>
See Also
E. coli, toxigenic, waterborne - USA (Washington) 990905100018Date: Mon, 6 Sep 1999 22:45:52 EDT
From: Karen R. Steingart, MD, MPH <KSteingart@aol.com>
On Saturday, August 28, 1999, Southwest Washington Health District and the
Washington State Department of Health received reports of four cases of
_Esherichia coli_ O157:H7 infection among children who resided in Clark
County, Washington (population 330,000). Interviews of the children's
parents revealed that three of the cases had swam in Battle Ground Lake, a
popular, spring fed lake in the northern part of the county, on August
20-21, and one case was a secondary case linked to a sibling swimmer. On
midnight August 28, the Health District closed the swimming beach because
of suspected transmission through lake water.
Prior to identification of the lake-associated cluster, the Health District
had been investigating an increase of reported cases (8 cases) of _E. coli_
O157:H7 with onsets in June, July, and early August. These cases included
two families with a total of five children, in which three cases were
believed to be due to secondary transmission. One case developed hemolytic
uremic syndrome (HUS). None of these early cases reported swimming in
Battle Ground Lake or had a common exposure identified. (Annual cases of
_E. coli_ reported in Clark County: 1996 - 17; 1997 - 12; 1998-7).
The week before the lake-associated cluster was identified, a second child
was hospitalized with HUS. This child reported swimming at Battle Ground
Lake on August 14. Samples of lake water obtained August 26 showed fecal
coliforms at 18 and 93 counts per 100ml, below the Washington State water
quality standard of 100 fecal coliforms per 100ml.
>From August 1 through September 6, 29 culture-confirmed cases of _E. coli_
O157:H7 have been reported. Altogether 24 cases are believed to be
associated with this outbreak. Of these 24 cases, 21 reported swimming at
Battle Ground Lake, August 14 - 28; two cases were contacts of swimmers;
and one case reported playing in the sand, but not swimming. Cases range in
age from one to 14 years, median age 5 years. Six cases have been
hospitalized, three with HUS. DNA finger printing by pulsed-field gel
electrophoresis (PFGE) is being performed on all isolates at the Washington
State Public Health Laboratory. Results to date show a consistent PFGE
pattern "the outbreak pattern" in ten isolates tested thus far.
Battle Ground Lake is approximately 27 acres wide. On a busy day the park
may be visited by upto 1000 people, although it is not known how many
actually swim. About 200 campers were there at any one time in August and
about 25% are from outside the southwest Washington area. The swimming area
is shallow and measures about 125 feet long by 100 feet wide, which puts
swimmers in very close contact. The site was extensively investigated and
it was found to be unlikely that wastewater systems, drinking water, or the
food concession stand are the source of the outbreak. The lake remains the
prime suspect, however, other possibilities have not been completely ruled
out and a case-control study is underway. Lake water, sediment, and animal
droppings have been collected for testing.
Of interest, during a 1991 swimming-associated outbreak at Blue Lake in
Multnomah County, Oregon, 21 culture-confirmed cases of _E. coli_ O157:H7
were reported (N Engl J Med 1994;331:579-84.)
--
Karen R. Steingart, MD, MPH
Health Officer
Southwest Washington Health District
2000 Fort Vancouver Way
Vancouver, Washington 98663
email: ksteingart@aol.com
[Thanks to Dr. Steingart for this comprehensive report. - Mod.ES
......................................es
--
*##########################################################*
ProMED-mail makes every effort to verify the reports that
are posted, but the accuracy and completeness of the
information, and of any statements or opinions based
thereon, are not guaranteed. The reader assumes all risks in
using information posted or archived by ProMED-mail. ISID
and its associated service providers shall not be held
responsible for errors or omissions or held liable for any
damages incurred as a result of use or reliance upon posted
or archived material.
************************************************************
Visit ProMED-mail's web site at <http://www.promedmail.org>.
Send all items for posting to: promed@promedmail.org
(NOT to an individual moderator). If you do not give your
full name and affiliation, it may not be posted. Send
commands to subscribe/unsubscribe, get archives, help,
etc. to: majordomo@promedmail.org. For assistance from a
human being send mail to: owner-promed@promedmail.org.
############################################################
############################################################