Published Date: 2007-08-24 22:00:09
Subject: PRO/AH> E. coli O157 - UK (Scotland): sliced meat susp. (04)
Archive Number: 20070824.2785
E. COLI O157 - UNITED KINGDOM (SCOTLAND): SLICED MEAT SUSPECTED (04)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Thu 23 Aug 2007
Source: Eurosurveillance weekly release, 2007 12(8) [edited]
Scotland has higher rates of _Escherichia coli_ O157 infection than
other countries in the United Kingdom (UK) and Europe (1). The
National Health Service's (NHS) Greater Glasgow and Clyde Public
Health Protection Unit is currently investigating an outbreak of _E.
coli_ O157 infection in Paisley. Between 10 and 17 Aug 2007, 9
confirmed cases of _E. coli_ O157 infection were identified, of which
6 have been confirmed as phage type 2.
Investigation, management, and control
On 10 Aug 2007, laboratories reported to NHS Greater Glasgow and
Clyde Public Protection Unit 2 cases of _E. coli_ O157 in residents
of a single postcode area of Paisley. Besides some unsurprising
common factors, one case reported buying food from branch A of a
supermarket chain, and the family of the 2nd case (who was too ill to
provide information) reported that he frequently shopped at branch B
of the same chain. A problem assessment group on 10 Aug 2007
concluded, however, that there was insufficient evidence to suggest a
common food source, and initiated further epidemiological,
microbiological, and environmental investigation.
On 13 Aug 2007, 5 further cases of _E. coli_ O157 infection were
reported. Of these, 3 were members of the 1st 2 cases' families. In
all, family group 1 consisted of 3 cases and family group 2 of 2. The
2nd member of family 2, a 66-year-old woman, died on 13 Aug 2007. The
remaining 2 new cases were apparently unrelated to each other and to
the earlier cases, except for the same area of residence.
Both the apparently sporadic cases reported having bought and
consumed cold sliced meats from the delicatessen at branch B of the
supermarket chain within the likely incubation period of 2 to 10
days. At least one member of each family group and the 2 apparently
sporadic cases had consumed various cold cooked sliced meats from the
delicatessens of the branches at which they shopped. There was no
link between the 2 branches and apart from the consumption of cooked
meats from the same supermarket chain, these cases had no other
common social or food history link.
Topside of beef was the cooked meat most frequently reported by
cases. This meat was supplied by a subsidiary of the supermarket
chain and distributed nationally exclusively to the chain.
The Outbreak Control Team (OCT) formulated several working
hypotheses. Firstly, that the product linking most of the cases was
nationally distributed. Alternatively, that there was an as yet
undiscovered link between the 2 branches of the supermarket chain.
3rdly, but less plausibly, that similar faults had occurred
independently in both branches of the supermarket chain.
All working hypotheses presupposed that the vehicles of infection
were the cold cooked meats sliced on the branch premises and did not
include other items sold from the delicatessens or pre-packed meats
from any of the branches of the chain. The OCT concluded that,
pending the results of further investigations, there was sufficient
evidence to issue a press release instructing the public not to
consume cold meats from the delicatessens of the 2 supermarket
branches. In addition, general practitioners, NHS24, hospital
departments, and the Scottish Executive were alerted.
At subsequent meetings of the OCT, on 14 and 15 Aug 2007, phage type
2 was confirmed in 4 cases. The OCT noted that there had only been 4
other cases of this uncommon type in Scotland in 2007, all resident
of Greater Glasgow and Clyde.
By 17 Aug 2007, 2 further cases had been confirmed. Both had consumed
cold meats from the delicatessen at branch B.
The total number of confirmed cases was now 9 (Table [for table, see
source URL - Mod.LL]). Despite a case of hemolytic uraemic syndrome
from an adjacent NHS board in a youth who had reportedly consumed
food from a different branch of the supermarket chain, and
unconfirmed reports of a case from elsewhere in the UK who had
shopped at the chain, the hypothesis of a nationally distributed
foodstuff was becoming less plausible. The hypothesis of a similar
fault having occurred at 2 branches of the same supermarket chain was
also unlikely. The OCT decided to recheck the only case history which
contradicted the hypothesis that a fault might have occurred only in
branch B. The index case in family group 1 subsequently confirmed
having bought and consumed cold cooked meats exclusively from the
delicatessen in branch B.
On 17 Aug 2007, the OCT therefore concluded that the most likely
cause of the outbreak was the cross-contamination of various cold
cooked meats at the delicatessen of a single branch of a supermarket
chain. However, epidemiological, microbiological, and environmental
investigations are still ongoing, and information is being gathered
from approximately 20 other people who have reported symptoms
following the consumption of meats from branches A and B of the
1. Locking M, Allison L, Rae L, Pollock K, Hanson M: VTEC in Scotland
2004: Enhanced surveillance and reference laboratory data. Health
Protection Scotland Weekly Bulletin 2005; 39: 51-2.
[Reported by: Stirling A, McCartney G
(<Gerry.McCartney@ggc.scot.nhs.uk>), Ahmed S, Cowden J]
[The summary of this ongoing investigation of a probable
cross-contamination _E. coli_ O157 outbreak in Scotland. - Mod.LL]