A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Wed 4 Aug 2010
Source: CDC, Salmonella Outbreak Investigations [edited]
CDC is collaborating with public health officials in multiple states,
the FDA, and the Department of Agriculture's Food Safety and
Inspection Service (USDA/FSIS) to investigate 2 multistate outbreaks
of _Salmonella_ infections, each involving a different serotype:
Hartford and Baildon. Both of these serotypes are rare, and ill
persons in both outbreaks have a similar age and geographic
distribution. Investigators are using DNA analysis of _Salmonella_
bacteria obtained through diagnostic testing to identify cases of
illness that may be part of these outbreaks.
Epidemiologic studies comparing foods eaten by ill and well persons
were conducted for both of these multistate outbreaks. In each study,
analysis indicates that eating at a Mexican-style fast food
restaurant chain, Restaurant Chain A, is associated with some
illnesses. Among persons eating at Restaurant Chain A, no specific
food item or ingredient was found to be associated with illness for
either outbreak. The numbers of new cases for the _S. enterica_
serotype Hartford outbreak have declined substantially since a peak
in early June 2010. The numbers of new cases for the _S. enterica_
serotype Baildon outbreak have declined substantially since a peak in
late June 2010. The number of new cases of illness associated with
these outbreak strains appears to have returned to baseline,
indicating the outbreaks are not ongoing.
In both outbreaks, the FDA worked with CDC and state partners to
conduct a traceback investigation. The tracebacks focused on produce
that ill individuals reported eating and that had been implicated in
previous outbreaks of salmonellosis. The extensive traceback effort
was initiated to determine if a common source or supplier could be
identified to help focus the epidemiologic investigations. No common
food source was identified in either traceback. The FDA also sampled
and tested produce items and did not find either outbreak strain. As
with previous outbreaks in which contaminated produce may be the
factor, produce tracebacks present substantial challenges because of
the short shelf life of the product and the industry's comingling of
product from multiple sources.
A widely distributed contaminated food product might cause illnesses
in a specific region and across the USA. Although neither outbreak
appears to be ongoing, indicating no continued risk of infection from
this source, CDC and its public health partners are continuing their
efforts to identify the specific contaminated product or products
that caused illness and will update the public on the progress of
this investigation as information becomes available.
These outbreaks can be visually described with a chart showing the
number of people who became ill each day. This chart is called an
epidemic curve or epi curve. Some _Salmonella_ illnesses associated
with these outbreaks that occurred after 19 Jul 2010, might not yet
be reported due to the time it takes between when a person becomes
ill and when the illness is reported. This takes an average of 2 to 3 weeks.
_S._ Hartford outbreak investigation
------------------------------------
As of 9:00 PM EDT on 1 Aug 2010, a total of 75 individuals infected
with a matching strain of _S._ Hartford have been reported from 15
states since 1 Apr 2010. The number of ill people identified in each
state with this strain is as follows: CO (1), GA (1), IL (5), IN
(11), KY (23), MA (2), MI (3), MT (1), NC (1), NH (1), NY (1), OH
(19), PA (1), SC (1) and WI (4). Among those for whom information is
available about when symptoms started, illnesses began between 30 Apr
2010 and 18 Jul 2010. Case-patients range in age from less than 1 to
80 years old, and the median age is 39 years. 57 percent of patients
are female. Among the 47 patients with available hospitalization
information, 15 (32 percent) were hospitalized. No deaths have been reported.
During 30 Jun to 9 Jul 2010, CDC and public health officials in
multiple states conducted an epidemiologic study by comparing foods
eaten by 43 ill and 97 well persons. Analysis of this study indicates
that eating at Mexican-style fast food Restaurant Chain A was
associated with illness. Ill persons (60 percent) were significantly
more likely than well persons (21 percent) to report eating at
Restaurant Chain A in the week before illness. Among persons eating
at Restaurant Chain A, no specific food item or ingredient was found
to be associated with illness based on an epidemiologic study
comparing foods eaten by 24 ill and 28 well persons. Ill persons
reported eating at 13 different locations of Restaurant Chain A in
the week before becoming ill. A total of 4 locations were identified
where more than one ill person reported eating in the week before becoming ill.
_S._ Baildon outbreak investigation
-----------------------------------
As of 9:00 PM EDT on 1 Aug 2010, a total of 80 individuals infected
with a matching strain of _S._ Baildon have been reported from 15
states since 1 May 2010. The number of ill people identified in each
state with this strain is as follows: CT (1), GA (1), IA (1), IL
(20), IN (4), KY (5), MA (1), MI (4), MN (5), NJ (6), NY (2), OH (6),
OR (1), WA (1) and WI (22). Among those for whom information is
available about when symptoms started, illnesses began between 11 May
2010 and 19 Jul 2010. Case-patients range in age from 1 to 82 years
old, and the median age is 47 years. 74 percent of patients are
female. Among the 68 patients with available hospitalization
information, 27 (40 percent) were hospitalized. No deaths have been reported.
During 18 to 30 Jul 2010, 2010, CDC and public health officials in
multiple states conducted an epidemiologic study by comparing foods
eaten by 52 ill and 125 well persons. Analysis of this study also
indicates that eating at Mexican-style fast food Restaurant Chain A
was associated with illness. Ill persons (65 percent) were
significantly more likely than well persons (15 percent) to report
eating a restaurant chain A in the week before illness. Among persons
eating at Restaurant Chain A, no specific food item or ingredient was
found to be associated with illness based on an epidemiologic study
comparing foods eaten by 33 ill and 96 well persons. Ill persons
reported eating at 22 different locations of Restaurant Chain A in
the week before becoming ill. 3 locations were identified where more
than one ill person reported eating in the week before becoming ill.
No common locations of Restaurant Chain A were reported by ill
persons in both the _S._ Baildon and _S._ Hartford outbreaks.
--
Communicated by:
ProMED-mail
[The Taco Bell chain has been elsewhere reported to be chain A in
this posting (see
It can be difficult to pin down a specific food vehicle since much of
the food in such fast food Mexican-style chains contains similar
ingredients such as lettuce, tomatoes, and jalapeno peppers. - Mod.LL]
[see also:
Salmonellosis, restaurant - USA: (CO), undercooked eggs 20100805.2653
Salmonellosis, serotype Hvittingfoss - USA (02): (IL) restaurants 20100612.1974
Salmonellosis, serotype Hvittingfoss - USA: (IL) restaurant chain
20100609.1932
2009
----
Gastroenteritis, gourmet restaurant - UK (03): norovirus 20090912.3211
Undiag. gastroenteritis, gourmet restaurant - UK (England) 20090307.0955
E. coli O157, restaurant - Canada, 2008: (ON), onions 20090623.2290
2008
----
E. coli O157, restaurant - Canada: (ON) 20081016.3283
Campylobacteriosis, restaurant - USA: (NY), raw clams susp. 20080924.3014
E. coli VTEC non-O157, restaurant - USA (03): (OK), O111 20080916.2904
E. coli VTEC non-O157, restaurant - USA: (OK), O111 20080902.2748
2007
----
E. coli O157, restaurant - USA (CA) 20070403.1131
Hepatitis A, restaurant - USA (TX)(02) 20070221.0645
Hepatitis A, restaurant - USA (TX) 20070220.0639
2006
----
E. coli O157, fast food - USA (multistate) (05): lettuce 20061214.3516
E. coli O157, fast food - USA (IA, MN): lettuce 20061214.3515
E. coli O157, fast food - USA (multistate): green onions 20061206.3441]
...................................ll/mj/mpp
*##########################################################*
************************************************************
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.
************************************************************
Donate to ProMED-mail. Details available at:
************************************************************
Visit ProMED-mail's web site at
Send all items for posting to: promed@promedmail.org (NOT to
an individual moderator). If you do not give your full name
name and affiliation, it may not be posted. You may unsub-
scribe at
For assistance from a human being, send mail to:
No comments:
Post a Comment