Investigation of a norovirus outbreak at a catered social event, Australian Capital Territory, 2024
DOI:
https://doi.org/10.33321/cdi.2026.50.042Keywords:
outbreak, norovirus, gastroenteritis, foodborne disease, hand hygiene, food handlerAbstract
Background
An outbreak of gastrointestinal illness was notified, affecting attendees at a private function in the Australian Capital Territory (ACT) in 2024. Investigations were conducted to determine the infectious agent, source of illness and mode of transmission, as well as to determine any public health actions required to prevent further illness.
Methods
Function attendees were surveyed using a modified standard gastroenteritis questionnaire. A confirmed outbreak case was defined as an individual who was unwell after attending the event and had a norovirus-positive clinical sample; a probable outbreak case was defined as an individual who was unwell with clinically compatible symptoms after attending the event. A case-control study was conducted to identify food items associated with illness. Food safety inspections were performed, and food samples were tested at the ACT Government Analytical Laboratory. Clinical samples were collected from unwell attendees and from an asymptomatic food handler.
Results
There were approximately 250–500 attendees at the function; 224 attendees completed the questionnaire and there were 65 cases (5 confirmed and 60 probable). A food handler who had previously been unwell, and who prepared fruit and meat platters for the function more than 96 hours after their symptoms had resolved, subsequently tested positive for norovirus. Environmental Health investigations showed the venue had good food practices and handwashing; the investigation identified no ongoing risks to the public. Testing of food samples did not detect any bacterial foodborne pathogens. Epidemiological investigations identified consumption of fresh fruit (odds ratio [OR]: 5.3; 95% confidence interval [95% CI]: 2.4–12.6; p < 0.001) and cured meat (OR: 2.7; 95% CI: 1.2–6.2; p = 0.02) as significantly associated with disease.
Conclusion
Epidemiological and clinical evidence indicates that norovirus was transmitted via contaminated fresh fruit and cured meat platters. Despite the venue having good food handling and handwashing practices, it was likely due to a food handler who had been unwell in the week prior to the function and prepared the implicated foods more than 96 hours after their symptoms resolved. This outbreak investigation shows that safe food practices and exclusion periods reduce but do not eliminate risk completely. Our findings highlight the need for continued education on effective hand hygiene in food preparation settings, especially following gastrointestinal illness.
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References
Hellard ME, Sinclair M, Harris AH, Kirk M, Fairley CK. Cost of community gastroenteritis. J Gastroenterol Hepatol. 2003;18(3):322–8. doi: https://doi.org/10.1046/j.1440-1746.2003.02959.x.
Kirk M, Ford L, Glass K, Hall G. Foodborne illness, Australia, circa 2000 and circa 2010. Emerg Infect Dis. 2014;20(11):1857–64. doi: https://doi.org/10.3201/eid2011.131315.
Barker SF, Zomer E, O’Toole J, Sinclair M, Gibney K, Liew D et al. Cost of gastroenteritis in Australia: a healthcare perspective. PLoS One. 201812;13(4):e0195759. doi: https://doi.org/10.1371/journal.pone.0195759.
Glass K. The annual cost of foodborne illness in Australia by food commodities and pathogens. Final report. Canberra: Food Standards Australia New Zealand (FSANZ); 3 August 2023. [Accessed on 28 October 2024.]
Svraka S, Duizer E, Vennema H, de Bruin E, van der Veer B, Dorresteijn B et al. Etiological role of viruses in outbreaks of acute gastroenteritis in The Netherlands from 1994 through 2005. J Clin Microbiol. 2007;45(5):1389–94. doi: https://doi.org/10.1128/JCM.02305-06.
Koopmans M, Vennema H, Heersma H, van Strien E, van Duynhoven Y, Brown D et al. Early identification of common-source foodborne virus outbreaks in Europe. Emerg Infect Dis. 2003;9(9):1136–42. doi: https://doi.org/10.3201/eid0909.020766.
Atmar RL, Estes MK. The epidemiologic and clinical importance of norovirus infection. Gastroenterol Clin North Am. 2006;35(2):275–90. doi: https://doi.org/10.1016/j.gtc.2006.03.001.
Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C et al. Food-related illness and death in the United States. Emerg Infect Dis. 1999;5(5):607–25. doi: https://doi.org/10.3201/eid0505.990502.
Lively JY, Johnson SD, Wikswo M, Gu W, Leon J, Hall AJ. Clinical and epidemiologic profiles for identifying norovirus in acute gastroenteritis outbreak investigations. Open Forum Infect Dis. 2018;5(4):ofy049. doi: https://doi.org/10.1093/ofid/ofy049.
Kaplan JE, Gary GW, Baron RC, Singh N, Schonberger LB, Feldman R et al. Epidemiology of Norwalk gastroenteritis and the role of Norwalk virus in outbreaks of acute nonbacterial gastroenteritis. Ann Intern Med. 1982;96(6):756–61. doi: https://doi.org/10.7326/0003-4819-96-6-756.
Goodgame R. Norovirus gastroenteritis. Curr Infect Dis Rep. 2007;9(2):102–9. doi: https://doi.org/10.1007/s11908-007-0004-5.
de Graaf M, van Beek J, Koopmans MPG. Human norovirus transmission and evolution in a changing world. Nat Rev Microbiol. 2016;14(7):421–33. doi: https://doi.org/10.1038/nrmicro.2016.48.
Atmar RL, Opekun AR, Gilger MA, Estes MK, Crawford SE, Neill FH et al. Norwalk virus shedding after experimental human infection. Emerg Infect Dis. 2008;14(10):1553–7. doi: https://doi.org/10.3201/eid1410.080117.
de Graaf M, Villabruna N, Koopmans MP. Capturing norovirus transmission. Curr Opin Virol. 2017;22:64–70. doi: https://doi.org/10.1016/j.coviro.2016.11.008.
Heijne JCM, Teunis P, Morroy G, Wijkmans C, Oostveen S, Duizer E et al. Enhanced hygiene measures and norovirus transmission during an outbreak. Emerg Infect Dis. 2009;15(1):24–30. doi: https://doi.org/10.3201/eid1501.080299.
Berg DE, Kohn MA, Farley TA, McFarland LM. Multi-state outbreaks of acute gastroenteritis traced to fecal-contaminated oysters harvested in Louisiana. J Infect Dis. 2000;181(Suppl 2):S381–6. doi: https://doi.org/10.1086/315581.
Bozkurt H, Phan-Thien KY, van Ogtrop F, Bell T, McConchie R. Outbreaks, occurrence, and control of norovirus and hepatitis a virus contamination in berries: a review. Crit Rev Food Sci Nutr. 2021;61(1):116–38. doi: https://doi.org/10.1080/10408398.2020.1719383.
Baert L, Uyttendaele M, Stals A, Van Coillie E, Dierick K, Debevere J et al. Reported foodborne outbreaks due to noroviruses in Belgium: the link between food and patient investigations in an international context. Epidemiol Infect. 2009;137(3):316–25. doi: https://doi.org/10.1017/S0950268808001830.
Hall AJ, Eisenbart VG, Etingüe AL, Gould LH, Lopman BA, Parashar UD. Epidemiology of foodborne norovirus outbreaks, United States, 2001–2008. Emerg Infect Dis. 2012;18(10):1566–73. doi: https://doi.org/10.3201/eid1810.120833.
Hall AJ, Wikswo ME, Pringle K, Gould LH, Parashar UD. Vital signs: foodborne norovirus outbreaks — United States, 2009–2012. MMWR Morb Mortal Wkly Rep. 2014;63(22):491–5. Available from: https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6322a3.htm.
Australian Capital Territory Government Health and Community Services Directorate (ACT Health). Food Safety for Businesses: Food Handlers. [Webpage.] Canberra: ACT Health; 7 October 2025. [Accessed on 9 April 2026.] Available from: https://www.act.gov.au/business/food-safety-for-businesses/food-safety-education/food-handlers.
Food Standards Australia and New Zealand (FSANZ). Compendium of Microbiological Criteria for Food. March 2022. Canberra: FSANZ; March 2022.
Australia New Zealand Food Authority. Australia New Zealand Food Standards Code - Standard 3.2.2 - Food safety practices and general requirements (Australia only). [Legislation.] Canberra: Australian Government Federal Register of Legislation; 24 August 2000. Available from: https://www.legislation.gov.au/F2008B00576/latest/text.
Glass K, McLure A, Bourke S, Cribb DM, Kirk MD, March J et al. The cost of foodborne illness and its sequelae in Australia circa 2019. Foodborne Pathog Dis. 2023;20(10):419–26. doi: https://doi.org/10.1089/fpd.2023.0015.
Hardstaff JL, Clough HE, Lutje V, McIntyre KM, Harris JP, Garner P et al. Foodborne and food-handler norovirus outbreaks: a systematic review. Foodborne Pathog Dis. 2018;15(10):589–97. doi: https://doi.org/10.1089/fpd.2018.2452.
Gallimore CI, Cubitt D, du Plessis N, Gray JJ. Asymptomatic and symptomatic excretion of noroviruses during a hospital outbreak of gastroenteritis. J Clin Microbiol. 2004;42(5):2271–4. doi: https://doi.org/10.1128/JCM.42.5.2271-2274.2004.
Qi R, Huang YT, Liu JW, Sun Y, Sun XF, Han HJ et al. Global prevalence of asymptomatic norovirus infection: a meta-analysis. EClinicalMedicine. 2018;2–3:50–8. doi: https://doi.org/10.1016/j.eclinm.2018.09.001.
Rumble C, Addiman S, Balasegaram S, Chima K, Ready D, Heard J et al. Role of food handlers in norovirus outbreaks in London and South East England, 2013 to 2015. J Food Prot. 2017;80(2):257–64. doi: https://doi.org/10.4315/0362-028X.JFP-16-083.
Barrabeig I, Rovira A, Buesa J, Bartolomé R, Pintó R, Prellezo H et al. Foodborne norovirus outbreak: the role of an asymptomatic food handler. BMC Infect Dis. 2010;10(1):269. doi: https://doi.org/10.1186/1471-2334-10-269.
Parashar UD, Dow L, Fankhauser RL, Humphrey CD, Miller J, Ando T et al. An outbreak of viral gastroenteritis associated with consumption of sandwiches: implications for the control of transmission by food handlers. Epidemiol Infect. 1998;121(3):615–21. doi: https://doi.org/10.1017/s0950268898001150.
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