Dispatch
Deer Meat as the Source
for a Sporadic Case of Escherichia coli O157:H7 Infection,
Connecticut1
Terry Rabatsky-Ehr,* Douglas Dingman,†Ruthanne Marcus,* Robert
Howard,‡ Aristea Kinney,‡ and Patricia Mshar,‡
*Connecticut Emerging Infections Program, New Haven, Connecticut,
USA; †The Connecticut Agricultural Experiment Station, New Haven,
Connecticut, USA; and ‡The Connecticut Department of Public Heath,
Hartford, Connecticut, USA
We report
a case of Escherichia coli O157:H7, which was acquired
by eating wild White-Tailed deer (Odocoileus virginianus).
DNA fingerprint analysis verified venison as the source of infection.
This pediatric case emphasizes the need for dissemination of information
to hunters regarding the safe handling and processing of venison.
Escherichia coli O157:H7 (O157) is a cause of acute infectious
diarrhea in humans and the leading cause of hemolytic uremic syndrome,
especially among children in the United States (1).
Many animals, including cattle, sheep, and goats, are known to harbor
O157; however, cattle are most often implicated as the zoonotic
source of human infection (2). Transmission is
usually attributed to contaminated foods. Meats, other than beef,
from which O157 has been isolated include pork, lamb, and poultry
(2,3). Although several reports document the presence
of O157 in deer (4-6), only one report (4)
has shown evidence of an O157 infection from eating venison. This
report was specific to the Black-Tailed deer (Odocoileus hemionus).
To our knowledge, this is the first case of O157 infection linked
with eating wild White-Tailed deer (Odocoileus virginianus)
meat.
Case
Report
A previously healthy 7-year-old boy was seen at a Connecticut emergency
room with a 3-day history of gastrointestinal illness. Symptoms
included bloody diarrhea, abdominal cramps, and nausea. The child
was treated with antibiotics as an outpatient; diarrhea resolved
after 6 days. The child’s stool sample was positive for O157. Stool
samples were not obtained from other family members.
Two days before the child’s onset of illness, his father butchered
and grilled freshly killed venison for the family. The child eat
a large quantity of undercooked (red), gamey-tasting grilled venison
tenderloin. His father ate a few bites of the venison; his mother
and sister ate none. The only other family member to report symptoms
of illness was the father, who reported having an “unsettled stomach”
without diarrhea the same day as his son’s onset of illness. Four
weeks later, O157 was recovered from a frozen sample of uncooked
venison obtained from the same carcass as the fresh, grilled tenderloin.
As part of routine disease surveillance, all patients with O157
infections who are reported to the Connecticut Department of Public
Health (CDPH) are interviewed by telephone, using a standardized
questionnaire. Parents of the 7-year-old boy were interviewed 2
weeks after the onset of symptoms, and information about his clinical
illness and potential exposures was collected. A second interview,
conducted 2 weeks later, sought additional information on illness
in other family members and on deer handling and processing practices.
Permission to collect samples of uncooked deer meat stored in the
family freezer was also obtained.
The O157 patient isolate was sent to the CDPH laboratory for confirmation,
H antigen determination, and subtyping by DNA fingerprinting using
pulsed-field gel electrophoresis (PFGE). The isolate was cultured
on sorbitol-MacConkey agar; sorbitol negative colonies were identified
as O157 by standard methods (7) and subtyped by
PFGE as described by Barrett et al. (8).
Three separate packages of White-Tailed deer meat, frozen for 25
days, were obtained from the child’s family and processed at the
Connecticut Agricultural Experiment Station. For all three packages
(steak, butterfly cut, and sausage pieces), a combined weight of
25 g frozen meat shavings were macerated, incubated in enrichment
medium, and immunomagnetically separated (IMS), according to the
manufacturers’ instructions (Dynal, Inc., Lake Success, NY). Magnetic
beads were washed during the IMS extraction procedure as reported
by Tomoyasu (9). Final suspensions of the magnetic
beads were plated on cefixime-tellurite sorbitol MacConkey agar,
sorbitol-negative colonies were confirmed using API20E (bioMérieux
Vitek, Inc., Hazelwood, MO), serotyped using the RIM E. coli
O157:H7 latex test (Remel, Lenexa, KS), and subtyped by DNA
fingerprinting using PFGE (8). To verify uniqueness
and confirm indistinguishable PFGE patterns, repeat subtyping by
PFGE of patient and venison isolates was done at the CDPH laboratory.
Restriction-fragment banding patterns were matched digitally using
a Gel doc 1000 System (Bio-Rad, Hercules, CA) and compared using
the Molecular Analyst Plus software (Bio-Rad). Molecular Analyst
Fingerprinting DST version 1.6 software (Bi0-Rad) for screening
DNA patterns permitted a 3% molecular weight matching-tolerance;
all matches were confirmed visually.
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Figure
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Click
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Figure. Pulsed-field
gel electrophoresis of O157 isolates from the Connecticut
child and the deer meat showing XbaI and BlnI-digested
genomic DNA....
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Both the clinical and venison O157 isolates were confirmed biochemically
as E. coli and serotyped as O157:H7. DNA fingerprint analysis
using PFGE demonstrated a pattern from the uncooked venison O157
isolate that was indistinguishable from the pattern of the clinical
O157 isolate (Figure) and unique (occurring
only once) among 26 patterns previously described.
Interviews with the child’s parents found no history of traditional
exposures for O157 infection. The child’s father provided information
regarding the deer hunt and venison processing. The deer was shot
(but not immediately killed) at noon in mid-November in Vermont.
After tracking the wounded animal for 2 hours, the hunters located
and field dressed the dead animal. An abdominal gunshot wound had
resulted in intestinal rupture; no intact internal organs were visible
when the deer was eviscerated in the field. No rinsing of the intestinal
cavity occurred, as is general practice among deer hunters. The
deer was dragged to a truck, brought back to camp, and hung outside
overnight before being transported from southern Vermont to Connecticut.
The deer was again hung outdoors overnight. Ambient air temperature
ranged from 0°C-13°C during this period. The following morning the
deer was skinned and cut into large sections. Individual sections
were further cut, trimmed, and rinsed under running water before
being packaged and stored in a home freezer. The tenderloin was
rinsed, placed on a clean plate, refrigerated, and grilled outdoors
that evening.
Discussion
This investigation implicates venison from White-Tailed deer (O.
virginianus) as the source of human O157 infection. We speculate
that the deer acquired O157 from cows grazing on dairy farms in
Vermont. The prevalence of O157 in White-Tailed deer sharing rangeland
with cattle has been well documented (4-6). In
addition, a field prevalence study in Georgia found that 3 (4%)
of 77 hunter-killed White-Tailed deer carried O157 (5).
Deer, like cattle, are transient carriers of O157 and are more likely
to be colonized with O157 in the fall and winter (6).
Thus, deer are most likely to carry O157 during the time of greatest
human exposure, the fall hunting season.
An estimated 11.3 million Americans hunt big game such as deer
or elk each year (10). Nationwide, the annual big
game hunting prevalence rate is 7%; regional rates vary from a low
of 4% in the Pacific States (Alaska, California, Hawaii, Oregon,
and Washington) to a high of 14% in the North Central States (Kansas,
Iowa, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota).
Relatively few cases of O157 infection have been associated with
eating venison over the many years of deer hunting. In a 1995 report,
a cluster of household cases was linked with eating jerky made from
Black-Tailed deer meat, and a sporadic case in 1987 of O157 infection
in Washington State was linked to venison (4).
Routine molecular subtyping of O157 isolates by the CDPH laboratory
allowed us to link the sporadic case of O157 with eating venison.
Fifty-five patient isolates were subtyped during that same year;
26 distinct patterns were identified. Twenty of these patterns (77%)
were unique. This marked heterogeneity of isolates is not limited
to Connecticut and emphasizes that many O157 infections are sporadic
and caused by contamination of raw foods as well as food preparation
and hygiene behaviors.
Multiple factors contributed to the contamination of the deer meat
that was eaten by the Connecticut child. The abdominal gunshot wound
increased the likelihood that intestinal contents initially contaminated
the deer carcass. In addition, the extended time it took the deer
to die, fecal contamination of the abdominal cavity, the warm day
and mild evening temperatures, and the 2-day interval between deer
kill and processing likely supported the dissemination and growth
of O157 throughout the carcass. Lastly, a large quantity of undercooked
venison tenderloin was eaten.
Hunters who handle wild game in the field are sometimes unaware
of the risk of contaminating the meat with foodborne pathogens while
dressing, handling, and transporting it. Contamination of game is
usually related to the manner in which the animal is killed, dressed,
handled, or processed. Improper temperature control, preservation,
and cooking may also contribute to contaminated game. Proper handling
of deer carcasses begins in the field with a clean shot to the neck
or torso (lungs, heart, liver) and quick removal of the intestines/entrails
(field dressing) from the abdominal cavity. If any of the internal
organs smell offensive, or exhibit discharge, or blood is seen in
the muscle, the flesh is unfit for consumption. The abdominal cavity
should be cleaned, dried, and cooled to <5°C until the meat is
processed.
This case study provides direct evidence for O157 in White-Tailed
deer and is the first report to link human illness to the presence
of O157 in this species of deer. Our findings contribute to the
body of evidence that eating venison may be a source of human infection
and highlight the need to provide hunters with guidelines for the
proper handling and processing of deer carcasses.
Acknowledgments
We thank Charles Welles and Giao Nguyen for their technical support
and Dr. James Hadler for his support and review of the manuscript.
This work was supported in part by the Connecticut Emerging Infections
Program, a Cooperative Agreement (U50/CCU111188-07) from the Centers
for Disease Control and Prevention.
Ms. Rabatsky-Ehr works as project coordinator for the Connecticut
Emerging Infections Program, Foodborne Diseases Active Surveillance
Network (FoodNet) and is a lecturer in the Department of Epidemiology
and Public Health, Yale University School of Medicine, New Haven,
Connecticut. Her research interests include molecular epidemiology
and antimicrobial resistance among bacterial foodborne pathogens.
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1Presented in part at the International
Conference on Emerging Infectious Diseases, Atlanta Georgia
(abstract # 118), July 2000.
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