Epidemiology and Outbreak Report
Josh Rounds, MPH Epidemiologist
Minnesota Department of Health
Outbreak of E. coli O104:H4 in Germany
As of June 8th
• 2,400 ill
• 642 HUS
• 24 deaths
• Case‐control study – cucumbers, tomatoes, and lettuce
• Sprouts?
Percentage of E. coli O157 Infections Resulting
in Hemolytic Uremic Syndrome by Age Group,
Minnesota, 1996-2009
% of O157 Infections Resulting in HUS
11.8%
10
8.0%
8
5.8%
6
4.2%
4
4.3%
3.9%
2.4%
2
1.5%
1.3%
30-39
40-49
0.4%
0
0-4
5-9
10-19
20-29
Age group (years)
50-59
60-69
70+
All
Ages
Percentage of E. coli O157 Infections Resulting
in Hemolytic Uremic Syndrome by Age Group,
Minnesota, 1996-2009
% of O157 Infections Resulting in HUS
11.8%
10
8.0%
8
5.8%
6
4.2%
4
4.3%
3.9%
2.4%
2
1.5%
1.3%
30-39
40-49
0.4%
0
0-4
5-9
10-19
20-29
Age group (years)
50-59
60-69
70+
All
Ages
Outbreak of E. coli O104:H4 in Germany
Approximately 30% of known cases have developed HUS
Normally 1 to 5% of cases in this age group
Why?
‐ Represents a huge outbreak (642/5% = 12840 cases?)
‐ This particular strain of STEC is more virulent
‐ Broader HUS case definition than we use
Phillip I Tarr, Carrie A Gordon, Wayne L Chandler
Lancet 2005;365:1073-86
"Antibiotics, antimotility agents, narcotics, and
non-steroidal anti-inflammatory drugs should not
be given to acutely infected patients, and we
advise hospital admission and administration of
intravenous fluids."
Non‐O157 STEC have Emerged as a Cause of HUS in Minnesota since 2000
• 11 HUS cases due to non-O157 STEC
– 10 children
– 2 fatalities
– Various serotypes
Number of Non‐O157 STEC, FoodNet 2000‐2009
Gould, CDC
Shiga Toxin‐Producing E. coli (STEC)
• Clinical laboratories test for E. coli O157 using culture
methods, and historically did not test for non-O157
• In recent years, clinical laboratories have been adding
or switching to non-culture methods for STEC
– Most of the tests used cannot differentiate O157
from non-O157
– Many laboratories in the U.S. no longer test for O157
using culture
Outbreak of E. coli O104:H4 in Germany
• Poor public communications
• Aggressively investigate sub-clusters of
illnesses (restaurants, work cafeterias)
• Tracebacks
Multi‐State Cluster of E. coli O157:H7 Infections, Dec. 2010‐Feb. 2011
February 7, 2011
• MDH PHL determined that 2 clinical E. coli O157:H7 isolates submitted through routine surveillance had indistinguishable PFGE patterns
• Wisconsin Department of Health called MDH regarding 3 case isolates with same pattern
• 1 matching case in Michigan
• Multi‐state investigation initiated
Multi‐State Cluster of E. coli O157:H7 Infections: 1st 6 cases
• Median age, 63 years
• 83% male
– 15‐year‐old male
– 55‐year‐old male
– 62‐year‐old male
– 64‐year‐old male
– 70‐year‐old female
– 78‐year‐old male
Interview Excerpts from 1st Two Minnesota Cases
Investigation of 1st 6 Cases
• All 6 reported in‐shell mixed nut or in shell hazelnut (filbert) consumption
– Hazelnuts were included in mixed nuts
– 2 reported only in‐shell hazelnuts (but not other in‐shell nuts)
• 5 of 6 purchased from bulk bins
Binomial Model of Probability of Number of Cases Eating Hazelnuts, Given Estimated Background of Hazelnut Consumption of 34%
Consumption of Hazelnuts among MN E. coli
O157:H7 Outbreak Cases (3/3) vs. Non‐peanut Nuts among MN Salmonella Cases (7/34)
Informational Traceback
• Traceback to common distributor: DeFranco & Son’s of California
?
• Recall of in‐shell hazelnuts from November 2 through December 22
E. coli O157:H7 Isolation from Hazelnuts
• March 5: E. coli O157:H7 isolated from hazelnuts from Minnesota case home
– March 7: outbreak PFGE subtype confirmed
• March 25: Outbreak PFGE subtype of E. coli O157:H7 isolated from mixed nuts returned to distributor in Wisconsin
• March 28: Outbreak PFGE subtype of E. coli O157:H7 isolated from mixed nuts collected from distributor in California
E. coli O157:H7 Outbreak Cases by Week of Illness Onset
E. coli O157:H7 and Hazelnuts
• New vehicle‐pathogen combination
• Example of why a company should maintain internal traceability
• Could lead to changes in production
– Previous Salmonella outbreaks with almonds led to pasteurization
• How did the hazelnuts become contaminated?