MAJOR ARTICLE
Tonsillopharyngitis Caused by Foodborne Group
A Streptococcus: A Prison-Based Outbreak
Michael Levy,1 Christine G. Johnson,2 and Ed Kraa3
1
Population Health, Corrections Health Service, Matraville, 2Discipline of Microbiology, Hunter Area Pathology Service, Newcastle, and
Food Inspection and Surveillance, Food Branch, New South Wales Health Department, North Sydney, Australia
3
An outbreak of tonsillopharyngitis due to Streptococcus pyogenes occurred among inmates of a rural correctional center in New South Wales, Australia. A total of 72 (28%) of 256 inmates became ill in December 1999.
S. pyogenes type M-75, T-25, which was opacity factor positive, was isolated from throat swab specimens
obtained from 5 of 57 inmates with primary cases and from 4 of 15 inmates with secondary cases, as well as
from specimens obtained from the hand wounds and throat of one of the food handlers. The consumption
of curried egg rolls (i.e., curried egg salad sandwiches) was the most likely association with this outbreak.
The presumed source of the food contamination was the food handler who had infected hand wounds. There
has been only one other outbreak of streptococcal pharyngitis reported from a prison. Other outbreaks have
been reported from military bases, nursing homes, and community picnics.
Foodborne outbreaks of group A streptococcal disease
are relatively rarely reported. We report a moderatesized outbreak in an institutional setting and present a
review of the reports of previous outbreaks. The correctional center at which the outbreak occurred is a
rural minimum-security prison in New South Wales,
Australia, located 300 km northwest of Sydney, Australia. Meals for the inmates came from 2 sources. Bread
rolls (i.e., sandwiches) for lunch were prepared on site,
whereas “cook-chill” evening meals were prepared in a
central kitchen in a correctional center in Sydney.
There were 256 male inmates in the prison on 17
December 1999, the date when a small number of inmates presented with tonsillopharyngitis. These patients were treated symptomatically for a presumed viral
illness. By the next day, there were 11 cases of tonsillopharyngitis, and inmates with new cases continued
Received 21 June 2002; accepted 8 October 2002; electronically published 7
January 2003.
Reprints or correspondence: Dr. Christine G. Johnson, Discipline of Microbiology,
Hunter Area Pathology Service, Locked Bag 1, Hunter Region Mail Centre, 2310,
Australia ([email protected]).
Clinical Infectious Diseases 2003; 36:175–82
2003 by the Infectious Diseases Society of America. All rights reserved.
1058-4838/2003/3602-0006$15.00
to present until 21 December, with a peak of 26 cases
diagnosed on 18 December. On 19 December, the presumptive diagnosis was changed to bacterial tonsillopharyngitis. Throat swab specimens were obtained from
6 of the new patients, and a policy of providing empirical treatment with penicillin for all additional cases
was introduced. Antibiotics were also offered to inmates
who had previously sought care. Five of the throat swab
specimens were subsequently found to be positive for
group A b-hemolytic streptococcus. On 22 December,
no additional cases were diagnosed, but 15 additional
inmates had bacterial tonsillopharyngitis diagnosed
from 23 through 26 December.
PATIENTS AND METHODS
Definitions and case ascertainment. A “case patient”
was defined as an inmate of the correctional center who
had culture-proven group A streptococcal throat infection or clinically purulent tonsillopharyngitis diagnosed between 18 and 26 December. Case patients who
received their diagnosis on or before 21 December (i.e.,
patients who presented within 72 h of the time of presentation of the first case patient) were regarded as
having primary cases. Those who presented on or after
December 23 were regarded as having secondary cases.
Foodborne Group A Streptococcus • CID 2003:36 (15 January) • 175
from workers in the central kitchen at the correctional center
in Sydney were cultured at the Centre for Infectious Diseases
and Microbiology, Institute of Clinical Pathology and Medical
Research (Westmead, Australia).
Analysis of survey results. Data were entered into Epi Info
software, version 6.04b (US Centers for Disease Control and
Prevention; Atlanta, GA). Analysis was done using the same
program.
Literature search. A literature search of MEDLINE was performed using various combinations of the search terms “group,”
“streptococcus,” “streptococcal,” “outbreak,” and “foodborne.”
The references found by this search were used to locate additional
reports.
Figure 1. Epidemic curve of cases of tonsillopharyngitis due to foodborne group A streptococcus in an outbreak among 256 inmates of a
rural correctional center in New South Wales, Australia.
The number of cases diagnosed was determined from clinic
records, and the epidemic curve was constructed using the date
of diagnosis as the time referent.
Investigation of meal arrangements at the correctional
center. Information about the usual routine for meals at the
prison was obtained by interviewing the inmates who worked
in the kitchen as well as the custodial staff who supervised
them. Information from the menus for 15–17 December were
used to prepare a questionnaire, which, on 22 December, was
administered to 154 inmates; the inmates completed the questionnaire either during a face-to-face interview or on their own.
Kitchen inspections. The on-site kitchen was inspected on
21 December, and the kitchen staff was interviewed. Throat
swab specimens were obtained from the 5 inmates who worked
in the kitchens. Skin lesions present on the hands of one member of the kitchen staff were also swabbed to obtain specimens
for bacterial culture. The kitchen at the correctional center in
Sydney that supplied the cook-chill meals was inspected on 22
December. Throat swab specimens were also obtained from
some of the kitchen staff in Sydney.
Laboratory investigations. The Division of Microbiology,
Hunter Area Pathology Service (Newcastle, Australia), cultured
the swab specimens obtained from inmates of the rural correctional center. By use of Streptex (Murex Biotech) reagents,
characteristic b-hemolytic colonies on horse blood agar were
identified as being of Lancefield group A. Emm gene determination, T-protein typing, and testing for the serum opacity
factor were performed at the Institute of Environmental Science
and Research Limited in Porirua, New Zealand. The emm gene
was amplified by PCR, and the product of the amplification
was subjected to restriction fragment–length polymorphism
analysis. Those isolates that yielded a distinct pattern, as well
as a representative subset of the isolates that yielded an identical
pattern, were sequenced. The throat swab specimens obtained
176 • CID 2003:36 (15 January) • Levy et al.
RESULTS
Time course and clinical features of the outbreak. The 72
case patients presented in 2 distinct groups: 57 (79%) presented
from 18 through 21 December, and 15 (21%) presented from
23 through 26 December. The median date of presentation was
19 December (figure 1). For tonsillopharyngitis, the primary
and secondary attack rates were 22% and 8%, respectively. The
denominator used for the calculation of the secondary attack
rate was 199 (the total no. of inmates [256] minus the total
no. of inmates with primary cases [57]); 15 secondary cases
were identified.
Inmate survey results. A total of 154 (60%) of 256 questionnaires were completed, but 67 were unsuitable for analysis.
The responses to the remaining 87 questionnaires were analyzed
(table 1). The only association with streptococcal tonsillopharyngitis was consumption of the curried egg rolls served
at lunch on 15 December; however, this association did not
reach statistical significance (P p .06 ; risk ratio, 1.50; 95% CI,
1.05–2.14).
Meal arrangements at the correctional center and findings
of kitchen inspections. Breakfast consisted of cereal provided
in single-serving packets and toast. There were limited on-site
kitchen facilities that were used to prepare lunch, which consisted
of bread rolls. Five inmates who were assigned to work in the
kitchen prepared bread rolls with 2 different fillings each day.
Two teams of kitchen workers each prepared bread rolls for half
of the inmates and handled both of the fillings. For curried egg
rolls (i.e., curried egg salad sandwiches), the eggs were boiled
and then stored in a refrigerator overnight. The next morning,
the shells were removed and the eggs mashed. Curry powder and
mayonnaise from a bulk storage container were added, and the
mixture was spread onto a buttered bread roll.
Although disposable gloves were available, gloves were not
being worn by the food handlers at the time of the kitchen
inspection. It was not possible to determine whether gloves had
been worn when the eggs were prepared on 15 December,
Table 1. Association of consumption of various foods with
cases of streptococcal illness occurring during an outbreak
among 256 inmates at a rural correctional center in New South
Wales, Australia.
a
Food (date consumed)
Devon/tomato roll (15 Dec 1999)
Risk ratio (95% CI)
1.13 (0.08–1.59)
Curried egg roll (15 Dec 1999)
b
1.50 (1.05–2.14)
Vegetarian meal (15 Dec 1999)
0.58 (0.02–5.78)
Lamb stew (15 Dec 1999)
1.10 (0.78–1.55)
Chicken/cheese roll (16 Dec 1999)
1.13 (0.86–1.50)
Baked beans roll (16 Dec 1999)
1.08 (0.60–1.95)
Beef pasta (16 Dec 1999)
1.23 (0.89–1.70)
Vegetarian meal (16 Dec 1999)
0.58 (0.07–4.71)
Tuna roll (17 Dec 1999)
1.13 (0.71–1.77)
Corned beef roll (17 Dec 1999)
1.05 (0.70–1.59)
Tempura fish (17 Dec 1999)
0.93 (0.63–1.38)
Vegetarian meal (17 Dec 1999)
4.50 (0.80–25.20)
NOTE. Association was determined on the basis of responses to a questionnaire administered to all inmates. The questionnaire was created using
information from the menus for 15–17 December. Data from 87 of the 256
questionnaires administered were analyzable.
a
b
“Roll” denotes a sandwich.
Curried egg salad sandwich.
whether the usual routine had been followed, or whether there
were any temperature-time violations of safe food-handling
practices. All members of the kitchen staff denied having any
lesions on their hands. However, the clinic staff remembered
dressing 5-day-old wounds for 1 of the 5 food handlers earlier
that day. The worker was removed from kitchen duty, and swab
specimens of the 2 hand wounds were obtained.
Since August 1999, there had been a cook-chill meal service
for the hot evening meals. These meals were prepared at a
correctional center in metropolitan Sydney and delivered twice
a week (journey length, ∼4 h) in a refrigerated truck. During
a visit to the facility in Sydney that prepared the cook-chill
meals, the hands of all workers present were examined for skin
lesions, and the workers were also asked about recent wounds
on their hands. There were no hand wounds evident, nor were
any reported by the kitchen workers from the previous week.
Throat swab specimens were obtained from 5 of the food
handlers.
Results of microbiological testing. Streptococcus pyogenes
was isolated from 5 of the 6 throat swab specimens obtained
on 19 December. These isolates were all found to be the same
type (M75, T25). Group A streptococcus was isolated from the
throat and skin lesions of one member of the kitchen staff, and
these isolates were also type M75, T25. A second member of
the kitchen staff also had a throat swab specimen that was
positive for group A b-hemolytic streptococcus, but the isolate
recovered was of a different type (M68, T nontypeable). Four
throat swab specimens with positive results were obtained from
patients who presented from 23 through 26 December. The
isolates recovered from these specimens were all type M75, T25.
Isolates recovered from the throat swab specimens obtained
from 4 patients who presented 2 weeks later were M type 87.
Group A b-hemolytic streptococcus was not detected in any
of the throat swab specimens obtained from the kitchen staff
that prepared cook-chill evening meals
Literature search. Twenty-six of the reports published in
English-language journals were obtained for review (table 2).
It was determined that at least 10 additional outbreaks have
been reported in non–English-language articles. These were not
reviewed.
DISCUSSION
Outbreaks of milkborne streptococcal tonsillopharyngitis were
not uncommon before the introduction of pasteurization
[36–44], and they were of such magnitude that they were recognized in the wider community setting. There have been only
∼30 foodborne outbreaks described in the English-language
literature, and most of these have been recognized in institutional settings or in association with community events (table
2). It is likely that other foodborne outbreaks occur but go
unrecognized because the victims are widely dispersed in the
community.
Incubation periods (median time until onset of disease) of
32–52 h are frequently reported, with the first case patients
developing symptoms as early as 6–8 h after exposure [21, 25,
31, 33]. In other outbreaks, the median time until onset has
been as long as 96 h, with the first case patients presenting 2
days after the probable exposure [10]. A longer incubation
period may be the result of a lower inoculum in the contaminated food. However, determination of the incubation period
is influenced by the data used to construct the epidemic curve.
In calculating the incubation period, use of the date of presentation for medical attention can delay the apparent onset
of the outbreak up to 24–32 h, compared with use of the time
to development of symptoms [5, 14]. Both the definition of
secondary cases as those that occurred either 172 h after the
onset of the first case or 172 h after consumption of the implicated food and the exclusion of these cases from the aforementioned calculation also influence the apparent incubation
period. Nevertheless, all of the reported foodborne outbreaks
have had a median incubation period of 1–4 days [44]. As in
the outbreak that we report here, the limitations of the investigation may preclude a definitive conclusion regarding the
source (and time) of exposure, rendering estimates of the incubation period tentative.
In some outbreaks, illness among people consuming leftovers has provided supportive evidence and has made it possible to distinguish between several possible foods as causes
Foodborne Group A Streptococcus • CID 2003:36 (15 January) • 177
Table 2.
Reference
Previous reports of foodborne outbreaks of group A streptococcal infection.
Date of
outbreak
Location
Setting
No. of
cases
178
[1]
Jul 1941
Massachusetts, US
Church lunch
Jun 1942
Western US
Army base
[3]
Nov 1942 United Kingdom
Air Force base
[4]
Nov 1943 North Carolina, US
Army base
[5]
Sep 1951
Army base
[6]
Mar 1952 Cambridge, United
Kingdom
Army camp
43
[7]
Feb 1957
Maryland, US
Charity lunch
[8]
Sep 1965
Buffalo, US
University cafeteria
—
[9]
Apr 1968
Colorado, US
Air Force Academy
∼1200
[10]
Jul 1973
Arizona, US
Community picnic–
Indian Reservation
255
Potato salad (included
a
sliced eggs)
Four food handlers, 1 of whom had a son with
pharyngitis
T3/13/B3264
[11]
Aug 1974
Florida, US
Prison
290
Egg salad sandwich
One of 5 inmates who peeled the eggs had a fever and a sore throat; a throat swab specimen
was positive for the outbreak strain
M9, T9
[12]
Apr 1975
Perm, Russia
[13]
1976
Ashdod, Israel
[14]
May 1980 Israel
Military base
41
Boiled egg salad
One of the kitchen workers had tonsillitis 3 days
before the outbreak; he and 5 other kitchen
workers were positive for the outbreak strain
M3
[15]
May 1981 Oregon, US
Microbiology
conference
∼300
No specific food
identified
Four of 10 food handlers had positive throat
swabs, and 3 had skin lesion swabs positive
for group A streptococcus
M–nontypeable, T9, SOR⫹
[16]
Jul 1982
Private party
34
—
A food handler, who was asymptomatic, had a
positive throat swab; a household contact had
acute pharyngitis shortly before the party
M–nontypeable, T12, SOR⫹
[17]
Nov 1983 Tennessee, US
Charity luncheon
20
Rice dressing
[18]
1983
[19]
Mar 1984 Missouri, US
New Hampshire, US
Japan
—
Factory
∼300
89
Ham
Typing of
Streptococcus isolates
Status of food handlers
[2]
Northern Germany
102
Food that was the
presumed cause of
the outbreak
One of 2 cooks had an early stage of scarlet fever Griffith 2
Not identified
—
Griffith 15
Tinned milk
Cook in charge of preparation of tinned milk was
infected with streptococci
Type 9
125
Creamed eggs
No findings despite thorough investigation
M5
265
Not identified
Thirty cooks; no specific findings
Custard (the “skin”)
One of the food handlers had a cough at the time
of custard preparation; a throat swab specimen
obtained 2 days later had a positive result
Egg salad
Food handlers had positive results of testing done Type 25
6 days after food preparation
Shrimp salad
Three food handlers who prepared the shrimp
salad had negative throat swab specimens
500–600
Tuna salad that contained Thirty persons present at the salad preparation;
boiled eggs
1 of 6 of those involved in egg preparation
was throat swab positive
185
Sour cream
—
447
Egg salad
—
—
—
Conference
luncheon
60
—
Mousse (most probably)
and macaroni salad
(less likely)
—
Type 9
Not typed (coinfection with S. flexneri)
M–nontypeable, T12
—
M-nontypeable, T12
Person who had prepared the implicated dish had M–nontypeable, T8/25, SOR⫹
had pharyngitis 3 weeks earlier and was culture
positive at the time of the outbreak
—
One food handler reported a sore throat; 5 food
handlers had negative throat swabs and no
visible hand lesions (8 days later)
—
—
179
[20]
Aug 1984
Puerto Rico
Private party
[21]
Jul 1986
Venice, Italy
5 Banquets in the
same restaurant
[22]
1988
Turkey
[23]
Jun 1988
Israel
[24]
1989
Russia
[25]
Apr 1990
Israel
[26]
May 1990 Sweden
[27]
1990
Sweden
[28]
Feb 1991
Israel
[29]
—
Military bases with
a central kitchen
—
Military base
Church party
179
58
439
Conch salad
Four food handlers had negative throat swab
specimens and were asymptomatic
M–nontypeable, T12, SOR⫹
Prawn cocktail in banSix of 18 staff members (5 of whom were from
quet 1, squills and custhe manager’s family) and 3 other children of
tard cake in banquets
the manager were positive for epidemic strain
2–4, and no identified
b
food in banquet 5
M28, T28
Bean salad with boiled
egg
M11, T3/13/B3264
No specific food
identified
—
Two of 12 asymptomatic food handlers had throat
swab specimens positive for group A streptococcus (not typed)
—
—
—
61
Boiled egg salad, cabbage salad, and probably egg salad
Two of 19 food handlers were symptomatic; both
had throat swab specimens positive for the epidemic strain
122, including Sandwiches, including
1 death
egg
Probable M29 variant,
T-nontypeable
—
M-nontypeable, T12
Six of 7 food handlers had positive throat swab
Fifty-one of 58 were T28; 5 of 58 were
specimens; 5 of these 6 attended the party and
T28/4; 2 of 58 were autoagglutinin.
ate the food. The one who did not attend the
The strain from the deceased and 4
party had nasal symptoms 2 days before the
random specimens were positive for
party and peeled eggs the day before the party;
erythrogenic toxins B and C.
a second food handler was symptomatic on the
day of the party.
—
—
Military base
75
Cabbage salad
Three soldiers were symptomatic before the
implicated meal; one was the cook who was
throat swab positive for the outbreak strain
M56, T28
May 1991 Louisiana, US
School banquet
71
Macaroni with cheese
sauce
Food handlers had negative throat swab specimens; 1 food handler had a positive result of
culture of a hand lesion
M9, T5/9
[30]
1991
Djibouti
Military base
[31]
Apr 1992
Israel
Air Force base
[32]
May 1993
[33]
May 1996 Aichi Prefecture, Japan
[34]
1997
Fukuoko Prefecture, Japan
—
—
—
—
—
[35]
1997
Ibaragi Prefecture, Japan
—
—
—
—
—
NOTE.
a
b
c
—
23
—
—
—
197
White cheese
—
—
Food handler was asymptomatic but was throat
swab positive; he did not taste the cheese and
was absent at the time of the outbreak
—
M-nontypeable, T11
M-nontypeable, T 8/25/Imp19
Military unit
162
Butter
—
T11
Sports meeting
244
Boiled eggs, boiled fish
paste, fried chicken,
c
and wakame-gohan
—
T1 (PFGE identical)
S. flexneri, Shigella flexneri; SOR⫹, serum opacity factor positive; US, United States.
Culture positive for epidemic strain.
A chopping board was also found to be culture positive.
All culture positive.
of the outbreak [7, 10, 26, 31, 33]; however, at the same time,
it has confounded the study of secondary spread of the illness.
Illness among people eating a meal as guests in an institutional
setting may provide useful supporting evidence as to which
meal—if not which item of food—was associated with the
outbreak [23, 25].
Reported attack rates of tonsillopharyngitis due to foodborne
group A streptococcus vary from 10% to 85%. The level of
preexisting immunity to the outbreak strain in the exposed
group of people is an important influence on the attack rate,
as is the level of contamination of the food. In the outbreak
reported by Getting et al. [1], increasing attack rates were seen
among groups of people consuming leftover food later in time,
and this was attributed to the ongoing multiplication of the
organism. In our investigation, as in the outbreak reported by
Boissard and Fry [6], it is possible that only half of the incriminated food was likely to be infective; this possibility not
only reduces the ability to demonstrate an association but, also,
reduces the apparent attack rate. The choice of denominator
used to calculate the attack rate also influences the result. In
most reports, the total number of attendees at the meal or
function associated with the outbreak has been used, but the
proportion of attendees who consumed the contaminated item
varied significantly. In instances in which data collection was
relatively complete and in which the attack rate was calculated
with a denominator denoting the number of attendees who
consumed the suspect food, attack rates as high as 80% have
been reported. The attack rate also depends on whether asymptomatic subjects with throat swab specimens found to be positive for the outbreak strain are included in the case definition.
This increases the apparent attack rate associated with outbreaks in which microbiological sampling of the entire exposed
cohort is able to be performed [28].
Secondary cases of streptococcal tonsillopharyngitis that occur in the context of a foodborne outbreak are believed to be
a result of the usual mode of spread via respiratory droplets.
Of major practical importance in outbreaks that occur in institutional settings is the question of whether secondary spread
would be expected to be of sufficient magnitude to warrant
prophylaxis. Guided by the only other report of an outbreak
in a custodial setting [11] and some of the reports of recent
outbreaks in military settings [25, 28, 31], in which the incidence of secondary cases was as low as 2%–5%, we did not
offer prophylaxis to asymptomatic inmates. The secondary attack rate of 8% among asymptomatic inmates was higher than
expected, although it was approximately half that described in
some other outbreaks [4, 9, 10]. In several outbreaks, cases
presenting 172 h after the onset of the first case were onequarter to one-third of the total number of cases.
A variety of factors influence the potential for secondary
180 • CID 2003:36 (15 January) • Levy et al.
spread, and the study of secondary spread is difficult. In an
institutional setting, “evidence of secondary spread of streptococcal infections after a foodborne epidemic is frequently
obscure because of the difficulty of observing an adequate population which is exposed only to secondary infection and not
to the primary source” [4, p. 194]. Some of the later cases,
rather than being the result of secondary spread, may be either
primary cases in which infection has resulted from a lower
inoculum of the organism or cases caused by infection occurring at subsequent meals (if there is further contamination by
the same infected cook or contaminated utensils). Evidence for
the latter possibility is provided in the report by Claesson et
al. [26], in which an apron cultured 6 days after the meal was
found to be positive for the epidemic strain of group A streptococcus, and, also, in the report by Gallo et al. [21], in which
attendees at 5 separate banquets were infected, different foods
were implicated for different cohorts, and the outbreak strain
was isolated from a chopping board as well as from members
of the restaurant staff.
In the community setting, ascertainment of secondary cases
is incomplete, and determination of a denominator for calculation of the attack rate is impossible. In closed communities,
the potential for secondary spread is partially determined by the
proportion of individuals who were not exposed to an infective
inoculum in the first instance. In the outbreak we have described,
it is possible that as few as one-quarter of the inmates may have
had primary exposure (if only half of the inmates had chosen
curried egg rolls and only half of the curried egg rolls were
contaminated). In most military outbreaks, ill soldiers were separated from unaffected soldiers immediately after presentation,
which would have limited the opportunity for secondary infection. It is unclear whether infected inmates were segregated during the outbreak in the Florida jail reported by Ryder et al. [11],
but penicillin therapy was initiated within 2 h of presentation.
The length of time that may elapse prior to initiation of penicillin
therapy before such therapy loses its effectiveness in preventing
secondary spread of illness is unknown.
In many of the reported outbreaks, the epidemic strain has
been isolated from throat swab specimens obtained from ⭓1
food handler. In some instances, the cook was symptomatic at
the time of food preparation [3, 6, 19, 25, 28]. More frequently,
the cook was asymptomatic, although some of the asymptomatic cooks had household contacts with a recent clinical illness.
One cook had had follicular tonsillopharyngitis 3 weeks previously but had received antibiotic therapy for only 3 days [14].
Skin lesions on the hands have also been implicated as a source
of group A streptococcus [29], although coexisting pharyngeal
colonization may also be present [15].
The types of foods implicated in foodborne outbreaks of
streptococcal tonsillopharyngitis suggest that contamination of
the hands with respiratory secretions is an important means of
infecting the food. Eggs, crustaceans, sandwiches, and salads,
all items that involve significant hand contact during preparation, account for 15 of 21 outbreaks in which a specific food
was identified. In addition, in virtually all of the reported outbreaks, there were time-temperature violations of safe foodhandling practices that would have allowed for multiplication
of the organism in the food incriminated in the outbreak. The
majority of reported outbreaks have occurred in the warmer
months.
The severity of the clinical illness has been reported to be
mild in some outbreaks [28] and severe in others, with myalgia
and prostration [5, 6, 9, 20, 26]. In some studies, gastrointestinal symptoms have been prominent, with up to 20% of patients reporting diarrhea, vomiting, or both [7, 11, 17, 21, 25,
33]. Getting et al. [1] demonstrated production of an enterotoxin by the causative organism associated with an outbreak at
a church reunion. Although the rate of complications usually
is low, serious complications do occur. In several of the outbreaks reported during the first half of the 20th century, scarlet
fever occurred in a significant percentage of patients. In the
outbreak that occurred at Fort Bragg in 1943 [4], there were
3 definite and 2 possible cases of rheumatic fever in a group
of 100 patients with tonsillopharyngitis. A 45-year-old man died
in a outbreak due to an isolate that produced pyrogenic exotoxins B and C [26].
It seems likely that symptom severity, the rate of complications, and the rate of acquisition among asymptomatic individuals are related to the serotype of the infecting organism,
although a high inoculum (compared with droplet exposure
via the respiratory tract) and exposure of the gastrointestinal
tract may be responsible for some of the clinical features.
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