Salmonellosis, USA, pet owners via dog food

Pythoness · #1 05-17-2008, 10:31 AM

During 1 Jan 2006 - 31 Dec 2007, CDC collaborated with public health
officials in Pennsylvania, other states, and the Food and Drug
Administration (FDA) to investigate a prolonged multistate outbreak of
_Salmonella enterica_ serotype Schwarzengrund infections in humans. A total
of 70 cases of _S._ Schwarzengrund infection with the outbreak strain (XbaI
pulsed-field gel electrophoresis [PFGE] pattern JM6X01.0015) were
identified in 19 states, mostly in the north eastern USA. This report
describes the outbreak investigation, which identified the source of
infection as dry dog food produced at a manufacturing plant in
Pennsylvania. This investigation is the 1st to identify contaminated dry
dog food as a source of human salmonellosis. After handling pet foods, pet
owners should wash their hands immediately, and infants should be kept away
from pet feeding areas.

On 8 May 2007, the Pennsylvania Bureau of Laboratories reported 3 cases of
_S._ Schwarzengrund infection with indistinguishable PFGE patterns to CDC's
PulseNet. On 9 Jun 2007, after PulseNet identified cases in Ohio and other
states, CDC's OutbreakNet team was notified of a potential multistate
outbreak of _S._ Schwarzengrund infections. During June 2007, the
Pennsylvania Department of Health (PADOH) interviewed persons identified by
PulseNet as infected with the outbreak strain of _S._ Schwarzengrund. These
initial interviews suggested exposure to dogs or dry dog food as a possible
source of infection. 13 infected persons from Pennsylvania were questioned
about dog-related exposures: 8 (62 per cent) owned 1 or more dogs, and the
other 5 reported regular contact with a dog. 7 of the 8 persons who owned
dogs were able to recall the types of dog food they had purchased recently.
Several brands had been purchased, but persons in the households of 6
patients recalled purchasing dog food products made by manufacturer A.
These interviews suggested exposure to dogs or dry dog foods as a possible
source of infection.

PADOH collected dog stool specimens and opened bags of dry dog food from
the homes of the 13 Pennsylvania patients. The outbreak strain of _S._
Schwarzengrund was isolated from 5 of 13 dog stool specimens and 2 of 22
dry dog food specimens collected from the homes. The contaminated dry dog
food bags were 2 different brands (brand A and brand B), both produced by
manufacturer A at plant A in Pennsylvania.

In July 2007, the Ohio Department of Health also interviewed persons
infected with the outbreak strain of _S._ Schwarzengrund and collected 2
dog stool specimens from 1 patient's home. The outbreak strain of _S._
Schwarzengrund was isolated from 1 of the dog stool specimens. The dog
recently had been fed brand A dry dog food, but the bag of dog food was no
longer available for testing.

Epidemiologic investigation
---------------------------
A case was defined as a laboratory-confirmed infection with the outbreak
strain of _S._ Schwarzengrund in a person residing in the USA who either
had symptoms beginning on or after 1 Jan 2006, or (if the symptom onset
date was unknown) had _S._ Schwarzengrund isolated from a specimen on or
after that date. During 1 Jan 2006 - 31 Dec 2007, a total of 70 human cases
of the outbreak strain of _S._ Schwarzengrund were reported to CDC via
PulseNet from 19 states (Figures 1 and 2, [for figures, see original URL -
Mod.LL]). The last reported illness onset date was 1 Oct 2007. No illness
was reported in pets.

The largest number of reported cases was in Pennsylvania (29 cases),
followed by New York (9) and Ohio (7). Among 61 ill persons whose age was
available, the median age was 3 years (range: 1 month-85 years), and 24 (39
per cent) were aged less than 1 year; of 45 persons whose sex was known, 22
(49 per cent) were female. Of 38 ill persons for whom clinical information
was available, 15 (39 per cent) had bloody diarrhea; of 45 persons whose
hospitalization status was known, 11 (24 per cent) had been hospitalized.
No deaths were reported.

Case-control study
------------------
To determine the source of infections caused by the outbreak strain of _S._
Schwarzengrund, the OutbreakNet team coordinated a multistate case-control
study during 17 Jul 2007 - 28 Sep 2007. Case-patient households were
defined as those with at least 1 member infected with the outbreak strain
of _S._ Schwarzengrund with an illness onset date or isolation date
occurring during the study period. For each case-patient household, 1 to 3
geographically matched control households were recruited using a
reverse-digit-dialing system. Persons in each case-patient and control
household were asked whether they had been exposed to dry dog or dry cat
food, which brands they usually purchased, and which brands they purchased
in the 2 weeks before illness onset (for cases) or the 2 weeks before
interview (for controls). Data were analyzed as a matched case-control
study, and a multivariable logistic analysis was conducted to control for
confounding from coexposures.

1 person was interviewed in each of 43 case-patient households and 144
control households in 8 states: Delaware, Maine, Michigan, Minnesota, New
York, North Dakota, Ohio, and Pennsylvania. Case-patient and control
households were excluded from analysis where questions were not answered.
Contact with a dog was reported by 34 (79 per cent) persons in case-patient
households compared with 86 (60 per cent) persons in control households
(matched odds ratio (mOR) = 2.7) (table, see original URL). Dry dog or cat
food produced by manufacturer A usually was chosen for purchase by members
of 19 (44 per cent) case-patient households compared with 14 (10 per cent)
of control households (mOR = 7.8; 95 per cent confidence interval (CI) =
2.6-27.8).

Among the 19 persons in case-patient households who usually purchased
manufacturer A pet food, 11 purchased brand A, 3 brand B, 5 brand C, and 3
brand D. All 4 brands were produced at plant A. Among the 4 brands, brand A
typically was purchased by 11 (26 per cent) persons in case-patient
households compared with 6 (4 per cent) persons in control households. In
multivariable analysis, purchase of brand A was associated with illness
(mOR = 23.7). In Pennsylvania alone, purchase of brand A also was
associated with human illness in multivariable analysis (mOR = 15.4; CI =
2.1-infinity).

Environmental investigation
---------------------------
During 2007, plant A produced about 25 brands of dry pet food; specific
distribution information for brands produced in plant A was not available.
Plant A labeled these dry pet foods with a 1-year shelf life (that is,
sell-by date). On 12 Jul 2007, PADOH staff members visited plant A and
collected 144 swabs of specimens from environmental surfaces; the outbreak
strain of _S._ Schwarzengrund was isolated from 1 sample. FDA tested
previously unopened bags of 7 brands (brands E, F, G, H, I, J, and K) of
dry dog food produced at plant A. 2 brands of dry dog food (E and F)
yielded the outbreak strain of _S._ Schwarzengrund. On 21 Aug 2007,
manufacturer A announced a voluntary recall of 50 pound bags of brand E dry
dog food and 5 pound bags of brand F dry dog food. On 26 Jul 2007,
manufacturer A suspended operations at plant A for cleaning and
disinfection. In mid-November 2007, plant A resumed normal operations.

[byline: Ferraro A, Deasy M, Dato V, et al]

Pythoness · #2 05-17-2008, 10:32 AM

Editorial note
--------------
The laboratory and epidemiologic evidence in this investigation indicates
that dry dog food produced by manufacturer A at plant A in Pennsylvania and
sold under several brand names caused human illness during 2006-2007.
Although previous reports in North America have associated _Salmonella_
infection with certain pet treats, this report is the 1st to associate
_Salmonella_ with contaminated dry dog food. The case-control study found
an association between infections in households and use of dry dog food or
dry cat food produced by manufacturer A. In addition, the outbreak strain
was isolated from 1) opened bags of dry dog food (brands A and B) that were
produced in plant A by manufacturer A, 2) stool specimens from dogs in
case-patient households that ate dry dog food produced in plant A, 3) an
environmental sample from plant A, and 4) 1 bags (brands E and F) of
previously unopened dry dog food produced in plant A.

A voluntary recall of specific-sized bags of 2 brands of dry dog food
issued by the manufacturer in August 2007 was based only on lot-specific
testing of finished unopened bags found to be positive for _Salmonella_ by
official FDA testing. Other sizes of bags of the 2 brands of dry dog food,
although produced at plant A, were not recalled. Other brands of dry dog or
cat food produced at plant A, including brands associated epidemiologically
and microbiologically with illness, also were not included in the recall.

Plant A ceased operations during July-November 2007 to allow for cleaning
and disinfection. However, because dry pet food has a 1 year shelf life and
all contaminated products were not recalled, contaminated dry pet food
might still be found in homes and could provide the potential for causing
illness. Only an estimated 3 per cent of Salmonella infections are
laboratory-confirmed and reported to surveillance systems (2); therefore,
this outbreak likely was larger than the 70 laboratory-confirmed cases
identified.

Most _Salmonella_ infections are acquired by handling or consuming
contaminated food products, particularly foods of animal origin. Infections
also are acquired by direct and indirect contact with farm animals,
reptiles, and occasionally pets. Investigations are ongoing to determine
how persons might acquire _Salmonella_ infections from dry pet food.
Factors under review include the handling and storage of dry pet food,
handwashing practices, exposure of children to dry pet food, and location
in the home where pets are fed. Although a specific source of contamination
for the pet food from plant A was not identified, the plant equipment might
have been contaminated, or contaminated ingredients might have been
delivered to plant A. Dry pet foods typically are extruded, and production
includes heat treatment, but the extruded food also is spray-coated with a
taste enhancer, usually an animal fat.

Outbreaks of human illness associated with animal-derived pet treats have
been described previously in North America (3-6). These include outbreaks
of _S._ Infantis infection caused by contaminated pig ear pet treats (3,4),
_S._ Newport infection caused by contaminated pet treats containing dried
beef (5), and _S._ Thompson infections associated with contact with
contaminated pet treats made from of beef or seafood (6). Follow-up
investigations of these outbreaks demonstrated that pet treats were
frequently contaminated with _Salmonella_ organisms. After a 1999 outbreak
in Canada, _Salmonella_ organisms were isolated from 48 (51 per cent) of 94
samples of pig ear pet treats purchased from local retail stores (5).
During 1999-2000 in the USA, _Salmonella_ strains were isolated from 65 (41
percent) of 158 samples of pig ear and other animal-derived pet treats
purchased from retail stores (7).

FDA regulates pet foods, treats, and supplements. If Salmonella is present,
these products are considered adulterated under the Federal Food, Drug, and
Cosmetic (FDC) Act. During 1 Jan 2007 - 27 Jul 2007, at least 15 pet food
products were recalled because of _Salmonella_ contamination (8). On 2 Nov
2007, a single brand of pet vitamin was recalled voluntarily by the
manufacturer because of possible _Salmonella_ contamination (9).
_Salmonella_ contamination has not been identified in canned pet food,
probably because the manufacturing process eliminates contamination.
However, _Salmonella_ contamination has been associated with raw pet food
diets (10).

Persons who suspect that contact with dry dog food has caused illness
should consult their health-care providers. Most persons infected with
_Salmonella_ develop diarrhea, fever, and abdominal cramps 12-72 hours
after infection, and the infection usually is diagnosed by culture of a
stool sample. Illness typically lasts 4-7 days, and most persons recover
without treatment. Infants, elderly persons, and persons with impaired
immune systems are more likely than others to develop severe illness. To
prevent _Salmonella_ infections, persons should wash their hands for at
least 20 seconds with warm water and soap immediately after handling dry
pet foods, pet treats, and pet supplements, and before preparing food and
eating. Infants should be kept away from pet feeding areas. Children aged
less than 5 years old should not be allowed to touch or eat pet food,
treats, or supplements.

References
----------
1. CDC. Salmonella annual summary 2005. Atlanta, GA: US Department of
Health and Human Services, CDC; 2007. Available at
<http://www.cdc.gov/ncidod/dbmd/phlis...ummary2005.pdf.>

2. Voetsch AC, Van Gilder TJ, Angulo FJ, et al. FoodNet estimate of the
burden of illness caused by nontyphoidal Salmonella infections in the
United States. Clin Infect Dis 2004; 38: S127-34.
3. Laboratory Centre for Disease Control, Public Health Agency of Canada.
Human health risk from exposure to natural dog treats. Can Commun Dis Rep
2000; 26: 41-2.
4. Clark C, Cunningham J, Ahmed R, et al. Characterization of Salmonella
associated with pig ear dog treats in Canada. J Clin Microbiol 2001; 39:
3962-8.
5. Pitout JD, Reisbig MD, Mulvey M, et al. Association between handling of
pet treats and infection with Salmonella enterica serotype Newport
expressing the AmpC beta-Lactamase, CMY-2. J Clin Microbiol 2003; 41: 4578-82.
6. CDC. Human salmonellosis associated with animal-derived pet
treats--United States and Canada, 2005. MMWR 2006; 55: 702-5.
7. White DG, Datta A, McDermott P, et al. Antimicrobial susceptibility and
genetic relatedness of Salmonella serovars isolated from animal-derived dog
treats in the USA. J Antimicrob Chemother 2003; 52: 860-3.
8. FDA. CVM update: FDA tips for preventing foodborne illness associated
with pet food and pet treats. Rockville, MD: Food and Drug Administration;
2007. Available at <http://www.fda.gov/cvm/cvm_updates/foodbornetips.htm>.
9. FDA. The Hartz Mountain Corporation recalls Vitamin Care for Cats
because of possible health risk. Rockville, MD: Food and Drug
Administration; 2007. Available at
<http://www.fda.gov/oc/po/firmrecalls/hartz10_07.html>.
10. Finley R, Reid-Smith R, Weese JS. Human health implications of
Salmonella-contaminated natural pet treats and raw pet food. Clin Infect
Dis 2006; 42: 686-91.

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Pythoness · #3 05-17-2008, 10:35 AM

The long and short of this is: If you think dry dog food is free of bacteria or food-borne illnesses because it's dry and has been through an extruding process, that would be false. Use the same caution when handling dog food that you would when handling raw meat.

It also brings up an interesting new argument for the vets and others who argue strenuously against raw meat diets on the basis that they contain Salmonella and other bacteria. (Uh-oh.. guess what.. so does kibble!)

I have no idea what brand of dog food this was, and they don't say. I've checked both the proMED website and the CDC. Nada. I'm not sure WHY they don't say, but they don't.

longnecker · #4 05-17-2008, 05:19 PM

Thanks guys

I certainly knew to be carefull in cleanup from the dog. But feeding her? Who knew!!!

Salmonellosis, USA, pet owners via dog food

Health and Wellness