Twenty two outbreaks of
Salmonella Enteritidis
in England and Wales have been reported to the Health Protection Agency’s
Communicable Disease Surveillance Centre (CDSC) between 1 June and 27 August
2003, compared with 14 in the same period in 2002 (1). A variety of
S.
Enteritidis phage types is involved: PT 1 resistant to nalidixic acid and
low level susceptibility to ciprofloxacin (Nx, Cp
L) three outbreaks;
PT 1e one outbreak; PT3 (Nx, Cp
L) one outbreak; PT4 three outbreaks;
PT6 three outbreaks; PT6a one outbreak; PT6a (Nx, Cp
L) one outbreak;
PT8 two outbreaks; PT12 one outbreak; PT14b one national outbreak including
three local outbreaks; PT21 (Nx, Cp
L) one outbreak; PT24 resistant
to tetracycline (T) one outbreak; PT53 one outbreak; PT56 one outbreak. In
total 356 people are known to have been affected. The largest outbreak is
a national outbreak of
S. Enteritidis PT14b so far affecting 117
people and an analytical study is underway to identify a contaminated food
vehicle(s). In seven outbreaks, microbiological evidence of contaminated food
vehicles has been found. Twelve outbreaks have been linked to Chinese restaurants,
three to bakeries, and one has occurred in a hospital. In response to the
recent outbreaks and increased incidence of
S. Enteritidis, food
items such as raw shell eggs, raw chicken, raw duck should be considered for
sampling as part of the local outbreak investigations. In addition, a public
health investigation of eggs has been initiated.
Between September and December 2002, 23 outbreaks of S. Enteritidis
were reported to CDSC, compared with 36 in the whole of 2001. In these outbreaks
over 1000 people were affected and 17 people infected with S. Enteritidis
died, although most of the deaths were not attributed directly to salmonella
infection (1). Three outbreaks, affecting over 450 people, were national.
Based on the epidemiological evidence two investigations into eggs in use
in the catering trade were initiated. As part of a public health investigation
in late 2002, 8501 shell eggs were sampled. Salmonella spp. was
isolated from 5.1% of imported Spanish eggs used in catering premises (4),
which compares unfavourably with salmonella levels of 0.3% found in eggs
(mostly produced in the United Kingdom (UK)) tested in a study of 34 296
eggs used in catering premises during April to May 2003 (5).
Advice issued by the UK Food Standards Agency re-iterating the need for
proper cooking of raw shell eggs (2), especially for vulnerable groups,
and suggesting that all importers and wholesalers heat treat eggs imported
from Spain (3) are still in force.