Foodborne Illness Outbreak Investigation in a High-Profile Sports Club
Cavanagh et al. Sports Medicine - Open
Foodborne Illness Outbreak Investigation in a High-Profile Sports Club
Kwendy Cavanagh 0
Travers Johnstone 0
Essi Huhtinen 0
Zeina Najjar 0
Peter Lorentzos 1
Craig Shadbolt 2
John Shields 2
Leena Gupta 0
0 Sydney Local Health District Public Health Unit , King George V Building, Missenden Road, Camperdown, NSW 2050 , Australia
1 Sports team physician , Sydney , Australia
2 New South Wales (NSW) Food Authority, 6 Avenue of the Americas , Newington, NSW 2127 , Australia
A foodborne illness outbreak involving an elite sports team was investigated by a public health unit in Sydney, Australia. An epidemiological association was established between gastrointestinal illness and the consumption of food supplied by an external caterer, with a lamb meal most strongly associated with illness. Genetically identical Salmonella isolates were identified from clinical specimens, residual food items, and an environmental swab taken from the catering premises. The training schedule and other club operations were significantly affected by this outbreak. Increased susceptibility due to regular shared activities and the potential for significant impact upon performance indicates that sports clubs must ensure that food suppliers comply with the highest standards of hygiene. Collaboration with public health authorities assists in source identification and prevention of further transmission.
Public health; Communicable diseases; Sports; Disease outbreaks; Athletes; Salmonella; Foodborne illness
An estimated 4.1 million cases of foodborne illness are
reported in Australia each year, and outbreaks are
]. Despite the frequency of such outbreaks in the
general population [
], infectious disease outbreaks of
any type in sporting teams are not frequently described
in the literature [
]. The few reported outbreaks in
sporting teams in Australia have mainly been caused by
environmental pathogens, such as Cryptosporidium [
] and Aeromonas hydrophila [
], rather than foodborne
organisms. In Australia, only two published outbreaks
relating to food and sports were identified on review; an
outbreak of gastroenteritis amongst six persons
associated with a team lunch [
] and a Staphylococcus aureus
outbreak amongst 22 participants of an elite event [
Internationally, reports of gastroenteritis in sports teams
have been linked to ice used in drinks [
], a football
], a rowing tournament [
] and more recently,
an outbreak of Salmonella affecting a number of European
ice hockey teams was linked to catering venues at the
]. However, such accounts are not numerous,
suggesting that foodborne illness outbreaks in sporting
teams are likely to be significantly underreported.
Sports teams may be at increased risk of infectious
diseases due to their close physical interactions, exposing
them to both point-source and person-to-person
3, 4, 12
]. Teams may also be at risk of
foodborne illness because of mass catering at training, events
or functions. Furthermore, when food is prepared for
specific dietary circumstances or needs of sportspersons,
adherence to strict food safety principles is required.
Large-scale sporting events will often have risk
management plans which include food safety as a significant
area for risk mitigation [
]. However, when catering is
on a smaller, more routine scale, such plans or
consideration of food safety may not be a particular priority.
This report describes an outbreak of Salmonella
amongst the team and staff of a professional sports club
during training season, the challenges involved in the
investigation, and practical implications for future
prevention and management of similar incidents amongst
In late 2014, a public health unit (PHU) in Sydney was
notified by the doctor of a professional sports team of 33
players and staff at a sports club who had developed
gastrointestinal symptoms within a 24-h period. In New
South Wales (NSW), Australia, suspected foodborne
illness outbreaks are notifiable to public health authorities
under the NSW Public Health Act 2010 [
]. In line with
NSW health guidelines [
], an outbreak investigation
was initiated in conjunction with the NSW Food
Authority (NSW FA), the lead food regulatory agency, to
determine the cause and control any ongoing risk.
The PHU conducted a retrospective cohort study, with
the cohort being defined as all individuals who attended
the sports club premises within a 72-h period
surrounding the first reported onset of illness. A case was
defined as a member of the cohort who developed
gastrointestinal symptoms within the 7 days following
their attendance at the club. A modified standard
] was used to collect details of any illness
and of foods consumed. Ninety-one people attended the
club during this period, forming the cohort; 76 of these
were interviewed (response rate 84%). Of those
interviewed, 35 people were identified as cases, of which 17
(49%) were players and 18 (51%) were staff. Frequencies
were calculated for symptoms, with the most common
being diarrhoea (97%), abdominal cramps (83%) and
fever (74%). Distribution of symptom onsets are
demonstrated in Fig. 1: Epidemiological curve showing
onset of gastrointestinal illness in members of the
sports club (n = 35).
Each day, a catering company supplied one type of
meal and a supplementary snack to the club. These
meals were generally reheated by microwave at the
club, though some were consumed cold following
nutritional advice. Relative risks (RR) and 95%
confidence intervals (CI) were calculated for each meal
item, as shown in Table 1.
Consumption of the lamb meal had the strongest
significant association with illness, with the other meals
also significantly associated with illness, though less
strongly. Additionally, the club reported that due to
illness, attendance at training dropped to approximately
70% in the week post-outbreak, and full attendance was
not regained until 2 weeks post-outbreak.
An environmental investigation was undertaken by
NSW FA. This involved site visits to the sports club and
to the catering premises that provided ready-to-eat
meals to the club; environmental and food samples were
collected from both premises. The inspection of the
caterer found that the business had adequate processes for
cooking of foods, and the cleaning and sanitising of the
premises was of a satisfactory standard. Although
disposable gloves were changed regularly, staff reported
that this was not always in conjunction with regular
hand-washing. An available chicken meal was reheated
in the club microwave to test the meal label instructions;
the chicken component of the meal was found to be at
an inadequate temperature of between 28 and 42 °C
(higher than 60 °C is recommended) [
All cases were encouraged to submit a stool sample for
microbiological testing. Faecal, food and environmental
samples underwent microbial analysis. Serotyping and
genetic sequencing, in the form of multiple-locus-variable
number tandem repeats analysis (MLVA) [
performed on all clinical, food and environmental isolates
positive for Salmonella species at a reference laboratory.
The day after the outbreak was reported, the first stool
sample returned positive for Salmonella and over the
following week, the remaining nine stool samples also tested
positive for Salmonella. These were later all typed as
Salmonella enterica serovar typhimurium, MLVA
3-1211-14-523. Four residual meals (two lamb, two pork) from
the club premises tested positive for S. typhimurium, two
with an identical MLVA to the clinical specimens. Quality
control and constituent component food samples
from the caterer were tested and found to be
satisfactory. One environmental swab was found positive for
S. typhimurium, again with an identical MLVA to the
matching clinical and food isolates.
This investigation identified a significant point-source
foodborne outbreak of S. typhimurium amongst
members of an elite sports team and the club’s staff, with
a strong epidemiological association between
gastrointestinal illness and the consumption of food
prepared by an external catering company. The evidence
of an epidemiological link is supported by
microbiological evidence of genetically identical isolates from
clinical samples, one residual lamb meal, a pork meal
and an environmental swab from the catering
company premises. Thirty-one team members and staff
had symptom onsets ranging from 6 to 58 h after
consumption of the lamb meal, consistent with the
usual incubation period for Salmonella [
It was postulated that the outbreak occurred due to
contamination of individual food portions during
preparation of batches made specifically for the sports club, as
there were no other reports of illness related to this
caterer during this time period. Furthermore, whilst
reheating the meals would have afforded some
protection, many members ate the meals cold and the
reheating procedures tested at the club did not heat the food
to sufficient temperatures to render it safe [
The impact of a foodborne illness on athletes has the
potential to disrupt training and competition schedules.
The attack rate in this outbreak was 38% amongst club
members, slightly lower than a previously reported
outbreak of Salmonella at a world rowing tournament
which affected up to 60% of some teams, preventing
participation of those affected [
]. It was fortunate that
this outbreak occurred during the pre-season training
period, which allowed players more flexibility to isolate
themselves and rest adequately. However, the pre-season
is also a period dedicated to building strength and
weight in preparation for the coming season. In the
opinion of the coaching staff of the sporting club, the
outbreak had an impact on the team’s long-term
performance during the following season, due to weight loss
amongst some players.
Fortunately, this outbreak was identified and notified
by the team physician so that public health action could
be taken to prevent further transmission and avert future
outbreaks from this particular source. However,
outbreaks of this nature can be underreported for a number
of reasons, including lack of knowledge of reporting
requirements or use of different healthcare providers by
different members of sports teams. Notification of illness
in elite athletes may also be hindered by concerns
regarding confidentiality [
] and potential media
exposure; noting that the media has previously reported
upon foodborne illness in high-profile teams [
Furthermore, public health investigations amongst
sportspersons can be challenging because team doctors
or the sportspersons themselves may be reluctant to
divulge necessary identifying or clinical information
because of the public profile of the team or individuals.
There were a number of limitations to our study. As
most cases were interviewed whilst they were still
Total club attendees
Total attendees consuming meal
(Day + 1)
Supplementary snack (daily)
*Reference group is club attendees on the same day that did not eat the specified meal
Relative risk* (95% C.I.)
2.09 (1.25, 3.50)
9.08 (3.55, 23.21)
2.33 (1.55, 3.51)
2.19 (1.36, 3.53)
unwell, it was not possible to ascertain the length of
illness and hence determine the overall impact of the
outbreak on the team and its training goals. In addition,
obtaining the sensitive, yet critical, clinical information
was a challenge for the investigation team. There were
delays in obtaining contact information for some
individuals who had attended the club but were unaffected
by illness. Although the first interviews were conducted
the day following notification to the PHU, the final
interviews were not completed until 18 days later. This may
have affected the interviewee’s ability to recall their
meals and activities during the period of interest,
potentially introducing recall bias. However, this may have
been mitigated by the use of a standard questionnaire.
This outbreak highlights the importance of
considering food safety when organising mass catering for elite
athletes, where the physical health of participants is
paramount. Although cross-contamination incidents can
occur randomly, clubs can reduce the risk of foodborne
illness outbreaks by ensuring that external caterers have
appropriate food safety procedures in place. This could
include requesting evidence of food safety training or
inspection reports. The hazard analysis and critical
control point (HACCP) risk management system [
designed to control food safety hazards, is used across a
wide range of settings, including at large sporting events
]. Organisations should consider using
HACCPaccredited companies when selecting food suppliers for
This point-source outbreak of S. typhimurium impacted
considerably upon the operations of a professional sports
club. The frequent communal activities undertaken in
sports clubs, coupled with the requirements for peak
physical health, may cause them to be significantly
affected by an outbreak of foodborne illness, despite the
general good health of their members. In the first
instance, stringent investigation of prospective food
suppliers is recommended and if incidents do occur, prompt
reporting to public health authorities will assist in
halting further transmission.
HACCP: Hazard analysis and critical control points; MLVA: Multi-locus-variable
number tandem repeats analysis; NSW: New South Wales; NSW FA: New
South Wales Food Authority; PHU: Public health unit
We acknowledge Associate Professor Vitali Sintchenko for advice regarding
MLVA testing and the unnamed club, team members and staff for assisting
us in this investigation.
This study was undertaken as part of the routine work of the PHU, so no
financial assistance was provided for this project.
Availability of Data and Materials
As all data was collected as part of a public health investigation under the
NSW Public Health Act 2010, it is necessary to preserve confidentiality and as
such, the dataset cannot be shared.
KC, TJ, EH, PL and ZN carried out epidemiological data collection. CS and JS
carried out environmental data collection. KC, TJ, EH and ZN contributed in
drafting the manuscript. ZN, LG, EH, KC, PL, and CS contributed in the
revision and approval of the manuscript. All authors read and approved the
All authors declare that they have no conflicting interests.
Ethics Approval and Consent to Participate
As all information was collected as part of a routine public health
investigation under the NSW Public Health Act 2010, ethics committee
approval was not required.
Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional affiliations.
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