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Outbreak of
Salmonella
Serotype
Hartford Infections Associated
With Unpasteurized Orange Juice
Kim A. Cook, MD, MSPH; Thomas E. Dobbs, MD; W. Gary Hlady, MD, MS; Joy G. Wells, MS;
Timothy J. Barrett, PhD; Nancy D. Puhr; Gayle A. Lancette; Dean W. Bodager, RS, MPA; Bill L. Toth, MPH;
Carol A. Genese, MBA; Anita K. Highsmith, MS; Keith E. Pilot; Lyn Finelli, PhD; David L. Swerdlow, MD
Context.—Acidic foods such as orange juice have been thought to be unlikely
vehicles of foodborne illness.
Objective.—Toinvestigateanoutbreakof
Salmonellaenterica
serotypeHartford
(
Salmonella
Hartford) infections among persons visiting a theme park in Orlando,
Fla, in 1995.
Design.—Review of surveillance data, matched case-control study, laboratory
investigation, and environmental studies.
Setting.—General community.
Participants.—Thesurveillancecasedefinitionwas
Salmonella
Hartfordor
Sal-
monella
serogroupC
1
infectioninaresidentoforavisitortoOrlandoinMayorJune
1995. In the case-controlstudy,casepatients were limited to themeparkhotelvisi-
tors and controls were matched to case patients by age group and hotel check-in
date.
Main Outcome Measures.—Risk factors for infection and source of implicated
food.
Results.—Sixty-two case patients from 21 states were identified. Both
Salmo-
nella
Hartfordand
Salmonellaenterica
serotypeGaminara(
Salmonella
Gaminara)
were isolated from stool samples of 1 ill person. Thirty-two case patients and 83
controls were enrolled in the case-control study. Ninety-seven percent of case pa-
tients had drunk orange juice in the theme park vs 54% of controls (matched odds
ratio, undefined; 95% confidence interval, 5.2 to undefined). The orange juice was
unpasteurizedandlocallyproduced.
Salmonella
Gaminarawasisolatedfrom10of
12 containers of orange juice produced during May and July, indicating ongoing
contamination of juice probably because of inadequately sanitized processing
equipment.
Conclusions.—Unpasteurized orange juice caused an outbreak of salmonello-
sis in a large Florida theme park. All orange juice was recalled and the processing
plant closed. Pasteurization or other equally effective risk-management strategies
should be used in the production of all juices.
JAMA. 1998;280:1504-1509
From the Foodborne and Diarrheal Diseases Branch,
Division of Bacterial and Mycotic Diseases, National
Center for Infectious Diseases (Drs Cook, Dobbs, Bar-
rett, and Swerdlow and Mss Wells, Puhr, and High-
smith), and the Epidemic Intelligence Service, Epide-
miology Program Office (Dr Cook), Centers for Disease
Control and Prevention, and the US Food and Drug Ad-
ministration, Southeast Regional Laboratory (Ms Lan-
cette), Atlanta, Ga; the Florida Department of Health,
Tallahassee (Dr Hlady and Mr Bodager); the Orange
County Public Health Unit, Orlando, Fla (Mr Toth); and
the New Jersey Department of Health and Senior Ser-
vices, Trenton (Ms Genese, Mr Pilot, and Dr Finelli).
Reprints: Kim A. Cook, MD, MSPH, Centers for Dis-
ease Control and Prevention, 1600 Clifton Rd NE, MS
A38, Atlanta, GA 30333.
AN ESTIMATED 2 to 4 million cases of
salmonellosisoccurannuallyintheUnited
States.
1
Although foods of animal origin
(eg, eggs, poultry, beef, dairy products)
are the vehicles of transmission in most
Salmonella outbreaks, contaminated
fresh fruits and vegetables are now rec-
ognized as a source of salmonellosis and
other foodborne diseases.
2-5
Unpasteur-
ized acidic fruit juices were previously
thoughttobesafe;however,recenthighly
publicized outbreaks of Escherichia coli
O157:H7 infections and cryptosporidiosis
occurring in 1996 in the northeast and
western United States associated with
unpasteurized apple cider and apple juice
illustrate the potential for acidic juices to
carry human pathogens.
6,7
We report an
outbreakofSalmonellaentericaserotype
Hartford (Salmonella Hartford) infec-
tions associated with another popular un-
pasteurized fruit drink, orange juice.
Salmonellosis caused by Salmonella
Hartford, a serogroup C
1
Salmonella (Sal-
monella C
1
), is uncommon. From 1984 to
1994, an annual mean of only 68 isolates
were reported to the Centers for Disease
Control and Prevention’s (CDC) national
Salmonella surveillance system, repre-
senting less than 0.2% of reported iso-
lates.
8
In June 1995, a review of Salmo-
nella serotype-based surveillance by the
New Jersey Department of Health iden-
tified a cluster of Salmonella Hartford in-
fections among 7 New Jersey residents re-
turning from vacation in Orlando, Fla.
None of them were acquainted with one
another or had traveled together. One per-
son was coinfected with Salmonella Hart-
ford and Salmonella enterica serotype
Gaminara (Salmonella Gaminara), a sero-
group I Salmonella (Salmonella I), which
is also exceedingly rare, with an annual
mean of only 40 isolates reported to the
CDC from 1984 to 1994. A preliminary in-
vestigation failed to identify a common ho-
tel, restaurant, or food exposure among ill
persons; however, all had visited a large
tourist theme park in Orlando during May
1995. An investigation was conducted
to determine the source and extent of
the outbreak.
METHODS
Case Finding
To find cases, we reviewed the CDC’s
national Salmonella surveillance sys-
tem for reports of Salmonella Hartford
1504 JAMA, November 4, 1998—Vol 280, No. 17
Salmonella
Associated With Unpasteurized Orange Juice—Cook et al
©1998 American Medical Association. All rights reserved.
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infections since May 1995 and asked
state health departments to interview
patients with this infection. We also re-
viewed Salmonella surveillance system
data to determine if there were signifi-
cant increases in reports of Salmonella
Gaminara or Salmonella I. All Florida
local health departments and area health
care facilities were notified of the out-
break and asked to immediately report
any cases of Salmonella Hartford, Sal-
monella Gaminara, or Salmonella C
1
or
I infections. A review of the theme park’s
employee and visitor medical clinic logs
was also conducted.
A confirmed case was defined as Sal-
monella Hartford infection in a resident
of or visitor to Orlando in May or June
1995. Because some laboratories sero-
group Salmonella isolates but do not
send all Salmonella isolates to their re-
spective state’s public health laboratory
for serotyping, a probable case was de-
fined as Salmonella C
1
infection in a resi-
dent of or visitor to Orlando in May or
June 1995.
Case-Control Study
To determine risk factors for infec-
tion, we conducted a matched case-con-
trol study. For this study, a case was
defined as diarrhea (3 or more loose
stools in 24 hours) in a theme park hotel
visitor who visited the park in May or
June 1995, with documented Salmonella
Hartford or Salmonella C
1
infection.
Cases were limited to visitors to the
theme park’s hotels because most pa-
tients had stayed at 1 of these 13 hotels.
If a family had more than 1 ill member,
only the first ill person in the household
was eligible. Cases were excluded if no
matched controls could be identified.
We attempted to enroll 3 controls per
case patient individually matched by age
group, hotel, check-in date, and number
of days spent visiting the theme park.
Potential controls were identified using
hotel records provided by the theme
park and contacted by telephone. Poten-
tial controls were excluded if they gave
a history of vomiting or diarrhea during
their visit to the theme park or within 7
days of returning home.
A standard questionnaire was admin-
istered by telephone with trained inter-
viewers. Information was collected on
tourist attractions visited, foods eaten,
beverages consumed, exposures to ani-
mals, and clinical illness.
Environmental Studies
Based on the results of our case-con-
trol study, we traced the implicated
product, orange juice, back through its
production process and conducted site
inspections of the involved processing
facilities and farms. Siteinspectionscon-
sisted of a review of processing proce-
dures, production plant sanitary condi-
tions and waterquality, and an overview
of growing and harvesting practices.
Laboratory Studies
Clinical isolates of the outbreak
strains of Salmonella were obtained
from the New Jersey and Florida de-
partments of health laboratories and se-
rotyping results were confirmed by the
CDC.
9
Implicated orange juice samples
were refrigerated and transported to
CDC for examination. The pH of orange
juice and the presence of fecal indicator
bacteria (total coliforms, fecal coliforms,
and E coli) were determined by stan-
dard methods.
10
Samples were examined
for Salmonella in duplicate using tetra-
thionate broth with brilliant green dye
(TET).
11
The TET wasincubated at 35°C
for 24 hours. It was then subcultured into
fresh TET and incubated at 42°C for 24
hours before streaking onto Hektoen en-
teric and brilliant green agar.
An independent microbiologic evalu-
ation of the implicated processing plant
was conducted by the University of
Florida Citrus Research and Education
Center in August and September 1995.
Specimen collection and culture meth-
ods are described elsewhere.
12
The US Food and Drug Administra-
tion (FDA), using a modified drag-swab
environmental sampling method, col-
lected whole fruit and environmental
samples from 2 Florida farms supplying
fruit to the implicated processor during
the outbreak period.
13
To isolate Salmo-
nella from swabs, the FDA used a modi-
fied culture method procedure with no-
vobiocin supplemental plating media
and delayed secondary selective enrich-
ment.
13
Antimicrobial susceptibility testing
forchloramphenicol,trimethoprim-sulfa-
methoxazole, tetracycline, ciprofloxacin,
nalidixic acid, ampicillin, sulfisoxazole,
streptomycin, kanamycin, gentamicin,
ceftriaxone, and amoxicillin–clavulanic
acidwasperformedonrepresentativehu-
man and environmental Salmonella iso-
lates by standard disk-diffusion tech-
niques.
14
Pulsed-field gel electrophoresis (PFGE)
was performed on isolates to subtype and
characterize the outbreak strains using
previously described methods for E coli
O157:H7
15
and Salmonella enterica sero-
type Typhimurium (Salmonella Typhi-
murium).
16
Statistical Analysis
Numerical data were entered and
analyzed with Epi Info, Version 6.02
(CDC).
17
Mantel-Haenszel matched odds
ratios (MORs) and95% confidence inter-
vals (CIs) were calculated to evaluate
associations between categorical vari-
ables.
18
Fisher exact test lower 95% CIs
were calculated for undefined MORs.
19
RESULTS
Fifty-two confirmed and 10 probable
cases of Salmonella Hartford infection
were identified among visitors to Or-
lando from 21 states. All onset dates
were in May and June and the peak of
illness onsets occurred during the week
of May 22 through 28 (Figure). No Or-
lando residents or theme park employ-
ees met the case definition and review of
the theme park’sclinical records showed
no notable increase in the number of em-
ployees or visitors presenting there with
gastrointestinal symptoms.
Forty-nine (83%) of 59 patients for
whom hotel information was available
stayed in 1 of the theme park’s 13 hotels
in the 7 days before illness onset; 2 per-
sons reported eating all meals exclu-
sively within the theme park. Patients’
ages ranged from 1 to 63 years (median,
10 years) and 53% were male. Salmo-
nella Hartford or Salmonella C
1
was cul-
tured from stool (n = 58), urine (n = 1),
blood (n = 2), or abscess (n = 1).
Both Salmonella Hartford and Sal-
monella Gaminara were isolated from
the stool of 1 patient; however, no addi-
tional isolates of Salmonella Gaminara
or Salmonella I were identified among
persons with a recent travel history to
Orlando and no significant increases
were observed in reports ofSalmonella.
Gaminara or Salmonella I infection dur-
ing the outbreak period from Florida or
other states.
Case-Control Results
Among the 62 persons identified
through case-finding efforts with prob-
able or confirmed Salmonella Hartford
infection, 32 were enrolled in the case-
control study along with 83 matchedcon-
trols. Thirty ill persons were excluded
because they did not stay in a themepark
1111842922158
May
Time of Onset
June
40
30
20
10
0
25
No. of Cases (N
=
62)
Probable Cases
Confirmed Cases
Salmonella enterica
serotype Hartfordinfectionsby
weekofdiarrheaonset among travelerstoOrlando,
Fla, May and June 1995.
JAMA, November 4, 1998—Vol 280, No. 17
Salmonella
Associated With Unpasteurized Orange Juice—Cook et al 1505
©1998 American Medical Association. All rights reserved.
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hotel (n = 7), were not the household’s
primary patient (n = 3), did not have di-
arrhea (n = 2), were identified after the
study ended (n = 2), could notbereached
by telephone (n = 15), or refused to par-
ticipate (n = 1).
The symptoms and signs reported for
the 32 persons enrolled in the case-con-
trol study included diarrhea (100%), ab-
dominal cramps (97%), fever (97%),
headache (73%), bloody stool (71%), and
vomiting (66%). The median duration of
illness was 7 days (range, 3-23 days), and
7 persons (22%) were hospitalized for a
median of 3 days (range, 1-5 days); there
were no deaths.
Consumption of orange juice in the
theme park was strongly associated with
illness (Table 1). Thirty-one (97%) of 32 ill
persons drank orange juice compared with
43 (54%) of 80 matched controls (MOR, un-
defined; 95% CI, 5.2 to undefined, P,.001).
The 1 case patient who reported no or-
ange juice consumption was matched to
controls who also reported no orange juice
consumption; therefore, the MOR and the
upper 95% CI are undefined. On univari-
ate analysis, waffles were also statisti-
cally associated with illness but were con-
sumed by only 16 (53%) of 30 ill persons.
A significant positive association be-
tween orange juice and illness remained
significant after those persons who re-
ported eating waffles were excluded from
the analysis.
“Character breakfasts” served in the
theme park were the only specific event
or meal associated with illness. Twenty-
nine (91%) of 32 ill persons attended a char-
acter breakfast compared with 48 (58%)
of 83 controls (MOR, 6.5; 95% CI, 1.8-
23.3). All ill persons who attended a char-
acter breakfast reported drinking or-
ange juice during their meal. Character
breakfasts are special breakfasts unique
to the theme park in which costumed car-
toon characters visit with the guests. They
are conducted in various locations
throughout the park but most are held in
the theme park’s hotels; however, no single
hotel accounted for the majority of ill-
nesses. No other tourist attractions in the
Orlando area or other pertinent expo-
sures, such as swimming in water parks
and hotel pools or direct contact with ani-
mals, were associated with illness.
Environmental Studies
The theme park received shipments of
orange juice every other day and report-
edly used all juice within 2 or 3 days of
delivery. Orange juice was distributed
and sold throughout the theme park and
was not opened before being received by
thepark’s hotels, restaurants, and attrac-
tions. Orange juice was served in sealed,
single-serving containers, poured from
larger containers intopitchers or glasses,
or poured into self-serve juice dispens-
ers. Eighty-eight percent of all orange
juice served at the theme park and all
orange juice served at character break-
fastswaspurchasedfromalocaljuicepro-
cessor and was unpasteurized.
The company that provided all of the
unpasteurized orange juice to the theme
park is a small citrus juice processing
plant (production capacity is approxi-
mately 40 000 L/d) located in a commu-
nity adjacent to Orlando; the plant pro-
duced only unpasteurized juices. Ap-
proximately 75% of the juice company’s
orange juice was sold to the theme park
and most of the remaining product was
sold by local Florida distributors. At the
juice company’s processing plant, whole
oranges were conveyed on moving pal-
lets through a phosphoric acid wash and
rinsed with water before being sliced in
half and juiced. The juice was then
chilled and bottled. The final product
contained no added water, sugar, pre-
servatives, or disinfectantsand had a 12-
to 17-day shelf life.
A site inspection of the juice company
identified several deficiencies in its pro-
cessing plant. The processing room was
poorly sealed from the outside environ-
ment: cracks and holes were visible in
the walls and ceiling, rodent and bird
droppings were present, and there were
reports of frogs being observed around
processing equipment. In addition, de-
spite reported twice-daily sanitization of
equipment, a buildup of precipitate cre-
ated from the mechanical reaming of the
orange was observed on the inside of the
fruit-squeezing machine. No problems
were reported with the chlorinated mu-
nicipal water used at the plant and no
fecal coliforms were detected in a bacte-
riological analysis of the water con-
ducted on August 1, 1995, by the Florida
Department of Health’s Public Health
Laboratory.
Four citrus growers provided the juice
company with oranges during the peak
outbreak period in May; 1 grove (grove A)
provided the majority (76%) of oranges.
Four other Florida citrus groves pro-
vided oranges used to produce contami-
nated juice in July; 1 grove (grove B) pro-
vided most (63%) of these oranges. These
2 orange groves (groves A and B) used
similar methods for growing, harvest-
ing, and picking fruit. Oranges were typi-
cally hand-picked, dropped to the ground,
collected in large bins, and shipped to the
juice company within 24 hours without be-
ing cleaned or refrigerated. However, the
groves were not associated with each
other and did not use common water
sources, fruit-picking crews, equipment,
or transport. They are separated by ap-
proximately 96 km (60 miles) and sold dif-
ferent varieties of oranges to the juice
company.
Laboratory Studies
Unopened and opened containers of
fresh and frozen orange juice were col-
lectedfromthethemepark,thejuicecom-
pany, and a local supermarket (where the
juice company’s orange juice was also dis-
tributed) by public health officials. The
pH of orange juice samples ranged from
4.1 to 4.5(mean pH, 4.3). All juice samples
tested contained coliforms (range, 5000
to .16 000 colony-forming units [CFUs]
per 100 mL), fecal coliforms (range, 220-
3500 CFUs per 100 mL), and E coli
(range, 170-1700 CFUs per 100 mL). Sal-
monella Gaminara (range, 2-4 CFUs per
100 mL) was cultured from 10 (83%) of 12
juice containers representing 4 lots pro-
duced in May and July 1995 (Table 2).
Seventy samples were collected from
the juice company’s processing plant
consisting of equipment swabs, fruit sur-
face swabs, and juice and other environ-
mental samples.
12
Salmonella Hartford
and Salmonella enterica serotype New-
port (Salmonella Newport) were iso-
lated from a toad found just outside the
juice-processing building. In addition,
salmonellae were isolated from un-
opened bottled juice produced in July
(Salmonella enterica serotype Rubis-
Table 1.—Association Between Cases of
Salmonella enterica
Serotype Hartford Infection and Selected Ex-
posures Among Theme Park Hotel Guests, Orlando, Fla, May-June 1995
Foods
Consumed Cases, No./Total (%)
Controls,
No./Total (%) MOR (95% CI)
*
Orange juice 31/32 (97) 43/80 (54) Undefined (5.2 to undefined)
Waffles 16/30 (53) 26/81 (32) 4.9 (1.4-17.1)
Eggs 24/31 (77) 48/82 (59) 2.3 (0.9-6.0)
Chicken 26/31 (84) 54/80 (68) 2.0 (0.7-5.8)
Cheese 23/31 (74) 50/77 (65) 1.7 (0.6-4.6)
Sausage 18/31 (58) 34/78 (44) 1.6 (0.7-3.9)
Milk 19/32 (59) 41/83 (49) 1.4 (0.6-3.3)
Fruit 25/32 (78) 62/79 (78) 1.2 (0.4-2.6)
Ice cream 25/31 (81) 65/79 (82) 1.0 (0.4-2.6)
Beef 25/31 (81) 66/80 (83) 0.9 (0.3-2.4)
Lettuce 20/32 (63) 58/82 (71) 0.8 (0.3-1.9)
Tomatoes 11/31 (35) 36/82 (44) 0.7 (0.3-1.9)
*MOR indicates matched odds ratio; CI, confidence interval.
1506 JAMA, November 4, 1998—Vol 280, No. 17
Salmonella
Associated With Unpasteurized Orange Juice—Cook et al
©1998 American Medical Association. All rights reserved.
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law), the surface of unwashed oranges
held in cold storage for several weeks
(Salmonella enterica serotype Saint-
paul), and 4 tree frogs (Salmonella New-
port) also found outside of the process-
ing building.
All 95 oranges sampled from 19 differ-
ent orange grove tracts (comprising ap-
proximately 250 acres) from groves A
and B had negative test results for Sal-
monella. Salmonella enterica serotypes
Braenderup and Muenchen, however,
were isolated from 2 (11%) of 18 envi-
ronmental swabs obtained from the soil
surrounding 18 orange trees located in 2
of 6 tracts sampled from grove A. Nei-
ther of these serotypes was isolated from
ill persons.
Antimicrobial susceptibility testing of
human isolates of Salmonella Hartford
(n = 17) and Salmonella Gaminara
(n = 1), orange juice isolates of Salmo-
nella Gaminara (n = 14), and the single
toad isolate of Salmonella Hartford de-
termined that all isolates were suscep-
tible to all antimicrobials tested. Seven
representative human isolates of Salmo-
nella Hartford were indistinguishable
by PFGE; however, the PFGE pattern
of the toad isolate and 9 reference iso-
lates were distinctly different from the
outbreak strain. Two PFGE patterns
(subtypes A and B) were identified from
10 Salmonella Gaminara isolates cul-
tured by the CDC from juice samples.
Isolates of Salmonella Gaminara with
PFGE pattern A were identified in juice
samples produced in both May and July.
However, both juice subtypes were dis-
similar from the subtype identified in the
single human isolate of Salmonella
Gaminara and from 5 reference isolates.
COMMENT
This outbreak of diarrheal illness af-
fected at least 62 visitors to a large tour-
ist theme park in Orlando. The case-con-
trol study and laboratory findings sup-
port the hypothesis that unpasteurized
orange juice contaminated with Salmo-
nella was the vehicle of transmission.
The case-control study determined
that orange juice was consumed by 97%
of ill persons andwas astrong risk factor
for illness. The association between ill-
ness and attendance at any character
breakfast, regardless of location, is ex-
plained by the fact that all such break-
fasts served only the juice supplied by
the park’s principal juice supplier; other
park venues served a variety of orange
juice brands. Waffles were statistically
associated with illness; however, only
53% of persons ate waffles andtheseper-
sons also drank orange juice.
In the laboratory investigation, every
lot of orange juice had positive findings
forfecal indicator organisms and multiple
lotscontainedSalmonella.AlthoughSal-
monella Hartford was not isolated from
orange juice, only 2 samples of juice from
the peak of the outbreak in May were
availableforanalysis;nevertheless,these
samples and multiple other samples from
July did yield Salmonella Gaminara, a
very rare serotype isolated from 1 ill per-
son who had a dual infection with Salmo-
nella Hartford. Salmonella Gaminara
isolated from orange juice obtained in an
Orlando supermarket not affiliated with
the theme park suggests that the out-
break may have extended beyond the
theme park. However, no patients in-
fected with Salmonella Hartford or Sal-
monella Gaminara reported consump-
tion of orange juice purchased outside the
theme park.
The dissimilarity of PFGE patterns
between human and toad isolates of Sal-
monella Hartford and between human
and juice isolates of Salmonella Gami-
nara is likely explained by 1 of several
factors. First, the PFGE pattern re-
ported for each isolate was based on the
testing of only a single colony; therefore,
we did not determine if multiple sub-
types of Salmonella Hartford or Salmo-
nella Gaminara existed within a single
specimen. Second, although Salmonella
Hartford and Salmonella Gaminara are
rarely isolated from humans, they may
be common in this environment, with a
significant amount of heterogeneity pre-
sent among serotypes. Nevertheless,
our PFGE analyses do notalterour main
conclusion that unpasteurized orange
juice contaminated with salmonellae was
the cause of this outbreak.
Although the true magnitude of the
outbreak is undetermined, a review of
human salmonellosis by Chalker and
Blaser
20
estimated that only 1% to 5% of
actual cases are reported. Given a 1% to
5% case-ascertainment rate and 62 cul-
ture-confirmed cases, we estimate that
between 1240 and 6200 cases of salmonel-
losis could have resulted from this out-
break. The unusually high percentage of
personswithsalmonellosisenrolledinour
case-control study with bloody stool
(71%)alsosuggestsmanymilderillnesses
were not detected. It is likely that only
those persons who were the most se-
verely ill with bloody diarrhea would
have sought medical treatment and been
evaluated with a stool culture.
The original source of the Salmonella
is unknown; however, salmonellae are
found in a broad variety of hosts, includ-
ing insects, reptiles, amphibians, birds,
and mammals, and may survive long pe-
riods in soil or water contaminated with
animal feces. Amphibians such as the
toad from which Salmonella Hartford
was isolated could easily have entered
the poorly sealed processing facility and
contaminated oranges and processing
equipment. In addition, because oranges
are frequently harvested after being
dropped to the ground, the exterior of
oranges may have become contaminated
with Salmonella directly from animals
or indirectly from soil, surface water
used for irrigation, or improperly pre-
pared manure used as fertilizer. Al-
though the implicated Salmonella sero-
types (Hartford and Gaminara) were not
isolated from the exterior of oranges
tested in this investigation, several lim-
iting factors must be considered. The or-
anges collected in our environmental in-
vestigations were unripe, obtained more
than 2 months after the peak outbreak
period, and picked primarily from the
Table 2.—Results of Examination of Containers of Juice Company’s Unpasteurized Orange Juice for
Escherichia coli
and
Salmonella
Species, May-July 1995
Production
Date
Container
Size, oz pH
Results
Escherichia coli
(CFUs/100 mL)
Salmonella
(CFUs/100 mL)†
5/05/95‡ 32 4.1 Not tested Positive
5/05/95‡ 32 4.1 Not tested Positive
7/15/95 8 4.2 Positive (500) Positive
7/15/95 8 4.3 Positive (300) Negative
7/15/95 8 4.3 Positive (441) Positive
7/15/95 8 4.3 Positive (800) Positive (2)
7/15/95 8 4.3 Positive (170) Negative
7/15/95 8 4.3 Positive (1100) Positive
7/15/95 8 4.4 Positive (900) Positive (4)
7/23/95§ 8 Not tested Positive (1700) Positive
7/23/95 128 4.3 Positive (300) Positive (2)
7/31/95\ 32 4.5 Positive Positive
*Data are colony-forming units (CFUs) per 100 mL calculated for a sample of positive specimens using the
most-probable-number method.
†
Salmonella enterica
serotype Gaminara was the only salmonellae serotype isolated.
‡These containers were frozen “vintage” samples provided by the juice company.
§This containerwas previouslyopened andsentto theCentersfor DiseaseControland Preventionbytheme park
officials for testing.
\This containerwas collectedfrom aretail store inOrlando, Fla(not affiliatedwith thetheme park),that purchased
the juice company’s product through a local distributor.
JAMA, November 4, 1998—Vol 280, No. 17
Salmonella
Associated With Unpasteurized Orange Juice—Cook et al 1507
©1998 American Medical Association. All rights reserved.
Downloaded From: http://jama.jamanetwork.com/ on 02/25/2013
trees and not the ground. Other Salmo-
nella serotypes were isolated from un-
washed orange surfaces and environ-
mental swabs collected from soil sur-
rounding orange trees in 1 grove provid-
ing oranges to the juice company.
Regardless of the environmental source
and means of contamination, once Salmo-
nella was introduced into the processing
plant, inadequate cleaning and sanitiza-
tion of processing equipment probably
contributed to production of contami-
nated juice. The presence of a specific fe-
cal indicator organism in all samples of or-
ange juice tested indicates improper
sanitation in the processing plant. The
identification of the same subtype of a rare
Salmonella serotype (Gaminara) in juice
produced during a 3-month span (May-
July) suggests that there was an ongoing
source of Salmonella within the plant.
Orange juice and other acidic fruit
juices are generally believed to be un-
usual vehicles oftransmission for human
pathogens. Although varying by season,
the average pH level of Florida orange
juice is 3.7 (range, 3.4-4.0).
21
While the
pH of orange juice implicated in this out-
break was less acidic than expected
(mean pH, 4.3), the FDA does not con-
sider foods with a pH level of 4.6 or less
to be “potentially hazardous.”
22
The
FDA Food Code also states that a food
that does not support the rapid and pro-
gressive growth of infectious or toxi-
genic microorganisms is not considered
potentially hazardous even though the
food may contain infectious or toxigenic
organisms at a level sufficient to cause
illness. However, recent outbreak inves-
tigations challenge these suppositions.
Orange juice has been identified asthe
vehicle of transmission in at least 5 pre-
vious foodborne outbreaks. Orange juice
was first reported as a vehicle of trans-
mission in an outbreak of typhoid fever
at a hotel in Cleveland, Ohio, in 1944.
23
Subsequently, it has been implicated in
outbreaks of hepatitis A virus in a hos-
pital in St Louis, Mo, in 1962,
24
probable
viral gastroenteritis among spectators
at a football game in California in
1966,
25,26
typhoid fever at a resort hotel
in New York in 1989,
27
and enterotoxi-
genic E coli in India in 1992.
28
Other acidic fruit juices have also been
implicated in outbreaks of gastroenteri-
tis. Unpasteurized apple cider and apple
juice were associated with outbreaks of
Salmonella Typhimurium infection,
29
E
coli O157:H7 infection,
6,7,30
postdiarrheal
hemolytic uremic syndrome (likely
caused by E coli O157:H7 infection),
31
and cryptosporidiosis.
7,32
Laboratory studies of the survival of
Salmonella and other bacterial patho-
gens in orange juice also support the hy-
pothesis that acidic juices can be vehicles
of pathogen transmission. Survival stud-
ies of salmonellae in orange juice using, in
part, strains isolated from case patients
and orange juice described in this out-
break investigation showed that salmo-
nellae survived in detectable numbers up
to 27 days at pH 3.5, 46 days at pH 3.8, 60
days at pH 4.1, and 73 days at pH 4.4.
33
In
a review by Mitscherlich and Marth,
34
in-
vestigators inoculated samples of orange
juice (pH of 3.0-3.1 held at 5°C) each with
10
6
/mL viable cells of Salmonella spe-
cies, Shigella sonnei, and Ecoli. Four deci-
mal reductions in the number of viable or-
ganisms required 27 days for Salmonella
species and E coli and 35 days for S son-
nei. Investigators in 1 of the aforemen-
tioned orange juice–associated typhoid fe-
ver outbreaks inoculated orange juice with
the outbreak strains and recovered vi-
able bacilli up to 6 days later.
27
Salmo-
nella enterica serotype Typhi has sur-
vived on the surface of cut and whole
oranges for 6 and 14 days, respectively.
34
Orange juice is the most popular fruit
drink in the United States. In 1995,Ameri-
cans consumed an estimated 20.7 L (5.45
gal) of orange juice per person, which ac-
counted for 60% of all fruit juice con-
sumed.
35
Although consumption data on
unpasteurized orange juice are limited, the
FDA recently estimated that 44.5 mil-
lion L (11.7 million gal) or 187 million 240-
mL (8-oz) servings per year of unpasteur-
ized orange juice are consumed in the
United States.
36
Thus, less than 1% of all
orange juice is consumed unpasteurized.
After our investigation, the theme
park decided to sell only pasteurized or-
ange juice. In addition, Florida public
health officials ordered a temporary
closing of the orange juice processor and,
with the assistance of the FDA, a recall
of the plant’s unpasteurized orange
juice. The Florida Department of Citrus
enacted new rules regulating the pro-
duction of fresh-squeezed unpasteurized
orange juice, including banning the use
of oranges picked from the ground for
the production of juice, washing fruit
with an acid wash or other equivalent
cleaning method, rinsing fruit with hy-
pochlorite or other equivalent bacteri-
cide, completely enclosing the juice-pro-
cessing area, conducting routine micro-
biologic surveillance of unpasteurized
juice, and establishing documented qual-
ity control, good manufacturing prac-
tices, or a Hazard Analysis Critical Con-
trol Point (HACCP) program.
37
Hazard
Analysis Critical Control Point is a pre-
ventive system of hazard control
whereby food producers are responsible
for identifying and evaluating food
safety hazards that can affect the safety
of their products and instituting con-
trols. Small Florida producers, such as
gift-fruit shippers, retail processors, and
roadside stand operators, are exempt
from these new regulations. Additional
research is needed to determine to what
extent these measures improve the
safety of unpasteurized juice, how
widely and consistently they are prac-
ticed, and what other possible interven-
tions need to be considered.
The potential role of fruit and veg-
etable juices in foodbornedisease has re-
cently begun to receive national atten-
tion. United States federal governmen-
tal agencies primarily responsible for
preventing foodborne disease (ie, CDC,
FDA, US Department of Agriculture,
Environmental Protection Agency), are
now collaborating on a national food
safety initiative. Ina report to President
Clinton in May 1997, development of new
preventive measures for fresh fruit and
vegetable juices was proposed.
38
As a consequence of recent outbreaks
associated with juices, the FDA recently
proposed new rules to improve the
safety of fresh and processed fruit and
vegetable juices and juice products.
39
The FDA’s proposal would mandate the
application of HACCP principles to the
processing of these foods to prevent bac-
terial, chemical, and physical contamina-
tion. Similar HACCP regulations have
already been enacted by the FDA for
seafood, meat, and poultry processors.
Under the proposed regulations, juice
processors would be required by the
FDA to demonstrate that their HACCP
program reduces the numbers of patho-
genic bacteria tothe same degreeas that
achieved by pasteurization. Until the fi-
nal rule is implemented, the FDA has
also proposed regulations (effective No-
vember 5, 1998) that require packaged
juice not pasteurized or otherwise pro-
cessed to control pathogenic microor-
ganisms to bear a warning statement in-
forming consumers of the potential risk
of foodborne illness associated with the
product. However, in the current ver-
sion of the proposal very small proces-
sors who manufacture fewer than
152 000 L (40 000 gal) of juice per year
would be exempt from HACCP require-
ments, and retailers that sell juice by the
glass would be exempt from both
HACCP and labeling regulations.
We describe the largest reported out-
breakofsalmonellosisassociatedwithun-
pasteurized orange juice. Although the
vast majority of orange juice and other
fruit and vegetable juices produced
within the United States are pasteurized
and safe to consume, this outbreak illus-
trates the importance of the current na-
tional debate and regulatory activity re-
garding the safety of unpasteurized
juices. Pasteurization or other risk-man-
agement strategies proven to be at least
as effective as pasteurization should be
1508 JAMA, November 4, 1998—Vol 280, No. 17
Salmonella
Associated With Unpasteurized Orange Juice—Cook et al
©1998 American Medical Association. All rights reserved.
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used in the production of juices, including
those previously thought to be too acidic
to transmit infection. Consumers need to
be aware that all unpasteurized juices
may potentially transmit enteric infec-
tions. Until production methods at least
as effective as pasteurization are devel-
oped, evaluated, and implemented, con-
sumers can reduce theirriskfor illness by
drinking only pasteurized fruit and veg-
etable juices.
The authors are indebted to the following indi-
viduals and organizations for providing invaluable
assistance in this investigation: Lori Stallard, Or-
ange County Public Health Unit, Orlando, Fla; Ri-
chard Hopkins and Roberta Hammond, Florida De-
partment of Health, Tallahassee; Betsy Woodward,
Florida Department of Agriculture and Consumer
Services, Tallahassee; Ronald Weber and Angela
Rhodes, FDA Florida District Office, Orlando;
Lurlene Dixon, FDA Southeast Regional Labora-
tory, Atlanta,Ga; and all of the helpful officials at the
theme park.
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