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Centers for Disease Control and Prevention
Atlanta, GA 30333
March 8, 1999

Attached is the annual summary of outbreaks of Escherichia coli O157:H7 infection reported to
CDC from January 1, 1998, through December 31, 1998. Please share this information with your
personnel who conduct E. coli O157:H7 outbreak investigations. If the attached 1998 outbreak
data from your state are incomplete or inaccurate, please contact Mary Evans at CDC’s
Foodborne and Diarrheal Diseases Branch. As the central location for the reporting of E. coli
O157:H7 outbreaks, CDC’s Foodborne and Diarrheal Diseases Branch would appreciate rapid
telephone or FAX reports of E. coli O157:H7 outbreaks regardless of the suspected source.

A total of 42 confirmed outbreaks of E. coli O157:H7 infection were reported to CDC in 1998;
in contrast, an average of 31 outbreaks were reported annually between 1994 and 1997. The
reason for this increase is unclear, but may be related to the widespread use of pulsed-field gel
electrophoresis (PFGE) by health departments to subtype E. coli O157:H7 strains. PFGE can link
both widely dispersed cases in different states and small clusters within states that might not
previously have been recognized as related.

In 1998, E. coli O157:H7 outbreaks were reported from 25 states and affected 777 persons. Onehundred fifty-three (20%) persons were hospitalized, 29 (4%) developed HUS and 3 (0.4%) died. Almost half of these illnesses occurred in four large outbreaks in North Carolina, Wisconsin (2 outbreaks), and Wyoming. Sixteen (38%) of the 42 outbreaks involved fewer than 5 persons,
compared with 5 (23%) of 22 outbreaks in 1997.

Cole slaw emerged as a new vehicle for E. coli O157:H7 infection and was responsible for
outbreaks in Indiana and North Carolina. Contaminated drinking water was responsible for a large
community outbreak in Wyoming, and a contaminated pool at a water park led to one death. Six
(14%) outbreaks were attributed to person-to-person transmission in day care centers, and no
vehicle was identified in 10 (24%) of outbreaks.

Ten outbreaks occurred in a community setting, including two multistate outbreaks resulting in
recalls of contaminated ground beef, and four outbreaks in which ground beef was the suspected
vehicle. Seven outbreaks occurred in restaurants, delis, or settings with catered food. In contrast,
only one outbreak was associated with these locations 1997. Four unrelated outbreaks occurred in
correctional facilities, involving six state prisons and one jail.

CDC’s Foodborne Diseases Laboratory Section is currently developing a national database of
pulsed-field gel electrophoresis (PFGE) patterns. CDC would like to determine the PFGE pattern
for E. coli O157:H7 isolates from each reported outbreak, including at least one isolate from a
patient and one isolate from the implicated food, if available. If your state or regional laboratory
currently performs PFGE on E. coli O157:H7 isolates, please forward patterns from each
outbreak to CDC. States that are not able to perform PFGE should contact Dr. Tim Barrett to
arrange subtyping of your isolates.

Please send reports of outbreak investigations to:

Mary C. Evans, M.P.H.
Foodborne and Diarrheal Diseases Branch
Centers for Disease Control and Prevention
1600 Clifton Road, Mailstop A-38
Atlanta, GA 30333

These reports will also be submitted to the Foodborne or Waterborne Disease Outbreak
Surveillance Systems, if appropriate.

We look forward to continuing to work together toward the control of this important public
health problem.

Escherichia coli O157:H7 Outbreaks, 1998

#	Onset month	State	City/County	Ill	Hosp	HUS/TTP	Deaths	Setting	Suspect vehicle	Vehicle confirmed?
1	February	WA	Spokane	7	1	1	0	Day care center	Person-to-person	N
2	April	TX	Greenville	5	4	3	0	Community	Ground beef	N
3	May	AZ	Mohave Co.	3	2	0	0	Picnic	Ground beef	N
4	May	CA	Stanislaus Co.	2	1	0	0	Restaurant	Salad	N
5	May	CT	Multiple	10	3	0	0	Community	Unknown	N
6	May	IL	Sangamon Co.	3	2	2	0	Private home	Well water	Y
7	May	IN	Indianapolis	33	6	0	0	Restaurant	Coleslaw	Y
8	May	VA	Fairfax/ Manassus	8	2	0	0	Community	Ground beef	N
9	May	WA	Tacoma	2	0	0	0	Community	Ground beef	Y
10	May May/June May/June June	NH MA ME RI	Multiple	7 9 5 1	1 0 0 0	0 0 0 0	0 0 1 0	Community	Ground Beef	Y
11	June	GA	Marietta	26	7	7	1	Water park	Swimming pool	Y
12	June	TX	Amarillo	4	4	0	1	Picnic	Unknown	N
13	June July	NY VA	Multiple	1 5	0 0	0 0	0 0	Community	Ground beef	Y
14	June	NY	Schoarie / Otsego	2	0	0	0	Community	Ground beef	Y
15	June	WI	Chippewa Co.	63	25	1	0	Community	Cheese curds	Y
16	June	WI	St. Croix Co.	47	10	3	0	Caterer	Fruit salad	N
17	June	WY	Alpine	114	21	4	0	Community	Water	Y
18	July	CA	San Joaquin	28	17	0	0	Prisons	Milk	N
19	July	ME		2	2	0	0	Community	Raw milk
20	July	MN	Ramsey Co.	3	1	1	0	Day care center	Person-to-person	Y
21	July	MN	Morrison Co.	7	1	0	0	Day care center	Person-to-person	Y
22	July	MN	Scott Co.	4	0	0	0	Lake	Water	Y
23	July	NC	Shelby	142	11	0	0	Restaurant	Cole slaw	Y
24	July	ND	Morton Co.	4	0	0	0	Picnic	Ground beef / p-t-p	N
25	July	OK	Granite	21	1	0	0	Prison	Unknown	N
26	July	OR	Baker Co.	2	1	0	0	Day care center	Person-to-person	N
27	July	UT	Salt Lake Co.	10	5	0	0	Prison	Hamburger / potatoes	Y
28	August	CA	San Diego	2	0	0	0	Marine base	Unknown	N
29	August	MN	Olmsted Co.	2	2	2	0	Fair	Unknown	N
30	August	MN	Hennepin Co.	30	3	0	0	Day care center	Person-to-person	Y
31	August	NY	Delaware	4	2	1	0	Camp	Unknown	N
32	August	NY	Oneida Co.	11	1	1	0	Deli	Macaroni salad	Y
33	August	VA	Floyd Co.	9	0	0	0	Day care center	Person-to-person	N
34	September	CA	Solano Co.	20	0	0	0	Church	Cake	Y
35	September	MD	Talbot Co.	4	0	0	0	Restaurant	Lettuce	N
36	September	WA	Tacoma	8	2	0	0	Fair	Unknown	N
37	September	WA	Kitsap Co.	4	0	0	0	Home	Unknown	N
38	October	CA	Sacramento	39	1	0	0	Jail	Unknown	N
39	October	FL	Dade Co.	16	1	0	0	Party	Unknown	N
40	October	NV	Carson City	14	2	1	0	Dairy farm	Contact w/ cattle	N
41	October	WA	Benton	21	7	2	0	School	Ground beef	N
42	November	WI	Dunn Co.	13	4	0	0	Church banquet	Meatballs / cole slaw	N
				777	153	29	3

Updated: 3/1/99