A foodborne outbreak of campylobacteriosis at a wedding - Melbourne, Australia, 2022.

Campylobacter is the most common bacterial cause of foodborne gastroenteritis in Australia; however, outbreaks caused by the pathogen are relatively uncommon. In March 2022, the Victorian Department of Health was notified of a gastrointestinal illness in 20 guests following attendance at a wedding reception. Two of these individuals were notified with laboratory-confirmed campylobacteriosis, and an investigation was undertaken to identify the source of the infection and implement strategies to prevent further illness. A case-control study was conducted to determine the likely source of infection. Cases were defined as attendees of the wedding reception, with onset of diarrhoea and/or abdominal cramping 1-10 days after attending the function. Controls were randomly selected from the remaining list of non-ill guests. Cases and controls were interviewed using a standardised, menu-based questionnaire. Food preparation processes were documented, and food samples collected. A total of 29 wedding guests met the case definition. Cases reported onset of illness 2-5 days following the wedding and major symptoms included abdominal cramping (100%), diarrhoea (90%), headache (79%), and fever (62%). Two cases were hospitalised, one with ongoing secondary neurological sequelae. Illness was significantly associated with consumption of a duck breast brioche canapé containing duck liver parfait (odds ratio = 2.85; 95% confidence interval: 1.03-7.86). No leftover food samples were available for testing. The investigation found that the duck canapé was the likely vehicle of infection. Consistent with the literature on Campylobacter transmission, it is likely that inadequate cooking of the duck liver for the parfait was the contributing factor that led to illness. This highlights the risks posed by undercooked poultry dishes, and shows that education of food handlers remains a priority.

Effect of Temperature and Rainfall on Sporadic Salmonellosis Notifications in Melbourne, Australia 2000-2019: A Time-Series Analysis.

Weather can impact infectious disease transmission, particularly for heat-sensitive pathogens, such as Salmonella. We conducted an ecological time-series analysis to estimate short-term associations between nonoutbreak-related notifications of Salmonella and weather conditions-temperature and rainfall-in Melbourne, Australia from 2000 to 2019. Distributed lag nonlinear models were created to analyze weather-salmonellosis associations and potential lag times on a weekly time scale, controlling for seasonality and long-term trends. Warmer temperatures were associated with increased risk of notification. Effects were temporally lagged, with the highest associations observed for warm temperatures 2-6 (greatest at 4) weeks before notification. The overall estimated relative risk of salmonellosis increased twofold at 33°C compared to the average weekly temperature (20.35°C) for the 8-week period preceding the disease notification. For Salmonella Typhimurium alone, this occurred at temperatures over 32°C. There were no statistically significant associations with rainfall and notification rates in any of the analyses performed. This study demonstrates the short-term influences of warm temperatures on Salmonella infections in Melbourne over a 20-year period. Salmonelloses are already the second most notified gastrointestinal diseases in Victoria, and these findings suggest that notifications may increase with increasing temperatures. This evidence contributes to previous findings that indicate concerns for public health with continued warm weather.

Anaphylaxis in Victoria: presentations to emergency departments, with a focus on drug- and antimicrobial-related cases.

OBJECTIVE: To investigate the causes, characteristics, and outcomes of anaphylaxis, particularly drug-related anaphylaxis, in Victoria during the first two years of mandatory notification. DESIGN: Review of all anaphylaxis cases reported by emergency departments to the Victorian Department of Health and Human Services. SETTING, PARTICIPANTS: People presenting to all public and private hospital emergency departments in Victoria, 1 November 2018 - 31 December 2020. MAIN OUTCOME MEASURES: Rates of drug- and food-related anaphylaxis, by age group; characteristics of cases of drug-related anaphylaxis. RESULTS: A total of 4273 anaphylaxis episodes were reported (females: 2292 cases, 54%); the overall anaphylaxis rate was 31.9 episodes per 100 000 person-years. The most frequently reported causes were foods (2659 cases, 62%); drugs were implicated in 533 cases (12%), insect venoms in 342 (8%), and other causes in 144 (4%). No deaths were recorded. The median age in cases of food-related anaphylaxis was 17 years (IQR, 6-29 years), and 45 years (IQR, 30-60 years) in cases of drug-related anaphylaxis. Hospitalisation was required by 1538 patients (36%) and intensive care by 111 (2.6%; 7% of people admitted to hospital). Antimicrobial drugs were implicated in 258 cases of drug-related anaphylaxis (48%) and non-steroidal anti-inflammatory drugs in 85 cases (16%). Penicillin-class agents were implicated in 143 cases of antimicrobial-related anaphylaxis (56%), cephalosporins in 80 cases (31%). CONCLUSION: Our review of notified cases of anaphylaxis in Victoria over two years provides insights into drug- and antimicrobial-related anaphylaxis in non-hospitalised people presenting to emergency departments.

Multistate Outbreak of Salmonella enterica Serovar Heidelberg with Unidentified Source, Australia, 2018-2019.

We report a multistate Salmonella enterica serovar Heidelberg outbreak in Australia during 2018-2019. Laboratory investigation of cases reported across 5 jurisdictions over a 7-month period could not identify a source of infection but detected indicators of severity and invasiveness. The hospitalization rate of 36% suggested a moderately severe clinical picture.

Monitoring the incidence and causes of disease potentially transmitted by food in Australia: Annual report of the OzFoodNet network, 2016.

ABSTRACT: In 2016, a total of 44,455 notifications of enteric diseases potentially related to food were received by state and territory health departments in Australia. Consistent with previous years, campylobacteriosis (n = 24,171) and salmonellosis (n = 18,060) were the most frequently-notified infections. Notable increases in incidence were observed for shiga toxin-producing Escherichia coli (n = 343; 166% increase), shigellosis (n = 1,408; 93% increase), campylobacteriosis (33% increase) and salmonellosis (30% increase) when compared with the historical five-year mean. The extent to which the introduction of culture-independent testing as a method of diagnosis has contributed to these increases remains unclear. In total, 188 gastrointestinal outbreaks, including 177 foodborne outbreaks, were reported in 2016. The 11 non-foodborne outbreaks were due to environmental or probable environmental transmission (nine outbreaks) and animal-to-person or probable animal-to-person transmission (two outbreaks). No outbreaks of waterborne or probable waterborne transmission were reported in 2016. Foodborne outbreaks affected 3,639 people, resulting in at least 348 hospital admissions and four deaths. Eggs continue to be a source of Salmonella Typhimurium infection across the country: 35 egg-related outbreaks, affecting approximately 510 people, were reported across six jurisdictions in 2016. Three large multi-jurisdictional Salmonella outbreaks associated with mung bean sprouts (n = 419 cases); bagged salad products (n = 311 cases); and rockmelons (n = 144 cases) were investigated in 2016. These outbreaks highlight the risks associated with fresh raw produce and the ongoing need for producers, retailers and consumers to implement strategies to reduce potential Salmonella contamination.

Characteristics of Campylobacter Gastroenteritis Outbreaks in Australia, 2001 to 2016.

Campylobacter spp. are a globally important cause of bacterial gastroenteritis, with Australia experiencing higher rates of illness than many comparable high-income countries. Despite the high disease incidence, outbreaks of campylobacteriosis in Australia are infrequently detected and reported. We examined the epidemiology of Campylobacter outbreaks in Australia, with particular emphasis on assessing transmission routes and evidence as reported during public health investigations. A national register of enteric and foodborne disease outbreaks was used to summarize data on all Campylobacter outbreaks reported in Australia between 2001 and 2016. Outbreak data were reviewed and analyzed for trends over time. Additional information was sought from state and territory epidemiologists, to validate transmission routes. A total of 84 Campylobacter outbreaks were reported, with 51 (61%) being classified as foodborne. Specific food vehicles were identified for 33 (65%) outbreaks, with 28 (85%) implicating chicken or chicken-containing dishes. Although no increase in the proportion of foodborne Campylobacter outbreaks was observed, examination of specific food vehicles demonstrated a significant increase in outbreaks because of poultry-liver containing foods (p = 0.04). One quarter of all 1042 outbreak-associated cases occurred in aged-care facilities (ACFs), including 17 associated hospitalizations and three deaths. After review of evidence data, 23 outbreaks (27%) were determined to have an unknown route of transmission, including 10 (43%) outbreaks occurring in ACFs. Campylobacter spp. remain a less commonly reported cause of gastroenteritis outbreaks in Australia. Although many reported outbreaks can be linked to foodborne transmission, over a quarter were unable to identify either a food vehicle or transmission source, particularly for outbreaks occurring in aged care. Increased efforts to improve evidence collection and understanding of transmission dynamics for outbreaks of campylobacteriosis, particularly in aged care, are required.

Whole-Genome Sequencing of Salmonella Mississippi and Typhimurium Definitive Type 160, Australia and New Zealand.

We used phylogenomic and risk factor data on isolates of Salmonella enterica serovars Mississippi and Typhimurium definitive type 160 (DT160) collected from human, animal, and environmental sources to elucidate their epidemiology and disease reservoirs in Australia and New Zealand. Sequence data suggested wild birds as a likely reservoir for DT160; animal and environmental sources varied more for Salmonella Mississippi than for Salmonella Typhimurium. Australia and New Zealand isolates sat in distinct clades for both serovars; the median single-nucleotide polymorphism distance for DT160 was 29 (range 8-66) and for Salmonella Mississippi, 619 (range 565-737). Phylogenomic data identified plausible sources of human infection from wildlife and environmental reservoirs and provided evidence supporting New Zealand-acquired DT160 in a group of travelers returning to Australia. Wider use of real-time whole-genome sequencing in new locations and for other serovars may identify sources and routes of transmission, thereby aiding prevention and control.

Waterparks are high risk for cryptosporidiosis: A case-control study in Victoria, 2015.

BACKGROUND: An increase in notifications of cryptosporidiosis was observed in Victoria between March and April 2015. Cases mostly resided in one metropolitan region and hypothesis-generating interviews identified common exposures to aquatic facilities. We conducted a case-control study to determine exposure source(s) and facilitate control measures. METHODS: Laboratory-confirmed cases of cryptosporidiosis from the region of interest notified between 1 March and 23 April 2015 were included. Controls residing in the same region were recruited from participants in a population health survey and frequency matched (2 per case) by age group. Details of exposure to potential risk factors were collected using a standardised telephone questionnaire for the 14-days prior to illness for cases, and an analogous exposure period for controls. Univariable and multivariable logistic regression were used to determine risk factors associated with illness using STATA SE 13.1. RESULTS: Thirty cases and 66 controls were included in the study. Half the cases were less than 12 years of age and 62% were female. Illness was most strongly associated with recreational water exposure at any waterpark (adjusted odds ratio (aOR)=73.5; 95% confidence interval (CI):6.74-802), and specifically at Victorian waterparks (aOR=45.6; 95% CI:5.20-399). Cases were linked with attendance at either a waterpark in the region or an adjacent region. As a result of this investigation, hyperchlorination was completed at identified facilities and swim hygiene information distributed. CONCLUSION: This study reinforces the potential for recreational water facilities, particularly waterparks, to act as a transmission source of Cryptosporidium infections. Continued communication to patrons is required to ensure healthy swimming practice in Victorian aquatic facilities.

A review of the public health management of shigellosis in Australia in the era of culture-independent diagnostic testing.

OBJECTIVE: To review the national case definition for shigellosis following the introduction of culture independent diagnostic testing by clinical laboratories and provide evidence to reform jurisdictional public health practices for the management shigellosis., . METHODS: A review of all Australian jurisdictional public health guidelines for shigellosis was conducted. Victorian 2014 shigellosis data were analysed: demographics and risk factors for cases identified by conventional culture or culture-independent diagnostic methods were described. RESULTS: There was considerable variation in reporting of cases to the National Notifiable Disease Surveillance System (NNDSS) by the eight Australian jurisdictions, with an array of classifications based on diagnostic testing methodologies. Analysis of Victorian 2014 shigellosis data found that culture positive cases were more likely to have reported men who have sex with men (MSM) as a risk factor than PCR positive only cases (p<0.0001) and less likely to have reported overseas travel during their incubation period (p<0.0001). Over a 10-year period (2005 to 2014), only two of 86 cases who were employed in high-risk occupations had ongoing positive faecal cultures after appropriate treatment. CONCLUSIONS: The national surveillance case definition for shigellosis should be reviewed to facilitate standardised reporting across Australia. All jurisdictions must consider the public health significance of PCR positive only results in their surveillance risk assessments to inform management of shigellosis cases.

Salmonella Typhimurium and Outbreaks of Egg-Associated Disease in Australia, 2001 to 2011.

INTRODUCTION: Salmonellosis is a significant public health problem, with eggs frequently identified as a food vehicle during outbreak investigations. Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis are the two most frequently identified causes of egg-associated disease in industrialized countries. In Australia, a comprehensive review of egg-associated outbreaks has not been previously undertaken. METHODS: Using a national register of foodborne outbreaks, we undertook a descriptive review of egg-associated outbreaks between 2001 and 2011. Included in our review was additional detail from the findings of trace back investigations conducted to the farm level. Evidence classifications were developed and applied to each outbreak based on descriptive and analytical epidemiology, food safety investigations, and microbiological testing of clinical, food, and trace back-derived samples. RESULTS: Over the study period, the proportion of foodborne Salmonella outbreaks linked to eggs increased significantly (p < 0.001). In total, 166 outbreaks were identified, with 90% caused by Salmonella Typhimurium. The majority of outbreaks were linked to commercial food providers, with raw egg use the major contributing factor. These events resulted in more than 3200 cases, more than 650 hospitalizations, and at least 4 deaths. Fifty-four percent of investigations used analytical epidemiology, food microbiology, and trace back microbiology to demonstrate links between human illness and eggs. Trace back investigations identified S. enterica indistinguishable from outbreak-associated clinical or food samples on 50% of sampled egg farms. CONCLUSION: Effective control of egg-associated salmonellosis remains a challenge in Australia, with Salmonella Typhimurium dominating as the causative serotype in outbreak events. Although outbreaks predominantly occur in the settings of restaurants, the high recovery rate of indistinguishable Salmonella on epidemiologically implicated egg farms suggests that further efforts to minimize infection pressure at the primary production level are needed in Australia.

Foodborne and waterborne infections in elderly community and long-term care facility residents,Victoria, Australia.

We calculated rates of foodborne and waterborne infections reported to the health department in Victoria, Australia, during 2000-2009 for elderly residents of long-term care facilities (LTCFs) and the community. We used negative binomial regression to estimate incidence rate ratios, adjusting for age, sex, and reporting period. We analyzed 8,277 infections in elderly persons. Rates of campylobacteriosis, legionellosis, listeriosis, toxigenic Escherichia coli infections, and shigellosis were higher in community residents, and rates of Salmonella infection were higher in LTCF residents. Each year, 61.7 Campylobacter infections were reported per 100,000 LTCF residents, compared with 97.6 per 100,000 community residents. LTCF residents were at higher risk for S. enterica serotype Typhimurium associated with outbreaks. Rates of foodborne infections (except salmonellosis) were similar to or lower for LTCF residents than for community residents. These findings may indicate that food preparation practices in LTCFs are safer than those used by elderly persons in the community.

A multistate outbreak of hepatitis A associated with semidried tomatoes in Australia, 2009.

BACKGROUND: A large outbreak of hepatitis A affected individuals in several Australian states in 2009, resulting in a 2-fold increase in cases reported to state health departments compared with 2008. Two peaks of infection occurred (April-May and September-November), with surveillance data suggesting locally acquired infections from a widely distributed food product. METHODS: Two case-control studies were completed. Intensive product trace-back and food sampling was undertaken. Genotyping was conducted on virus isolates from patient serum and food samples. Control measures included prophylaxis for close contacts, public health warnings, an order by the chief health officer under the Victorian Food Act 1984, and trade-level recalls on implicated batches of semidried tomatoes. RESULTS: A multijurisdictional case-control study in April-May found an association between illness and consumption of semidried tomatoes (odds ratio [OR], 3.0; 95% CI 1.4-6.7). A second case-control study conducted in Victoria in October-November also implicated semidried tomatoes as being associated with illness (OR, 10.3; 95% CI, 4.7-22.7). Hepatitis A RNA was detected in 22 samples of semidried tomatoes. Hepatitis A virus genotype IB was identified in 144 of 153 (94%) patients tested from 2009, and partial sequence analysis showed complete identity with an isolate found in a sample of semidried tomatoes. CONCLUSIONS: The results of both case-control studies and food testing implicated the novel vehicle of semidried tomatoes as the cause of this hepatitis A outbreak. The outbreak was extensive and sustained despite public health interventions, the design and implementation of which were complicated by limitations in food testing capability and complex supply chains.

Surveillance for outbreaks of gastroenteritis in long-term care facilities, Australia, 2002-2008.

BACKGROUND: Each year in Australia, health departments investigate hundreds of gastroenteritis outbreaks. Long-term care facilities (LTCFs) for elderly persons are a common setting for these outbreaks and can result in potentially serious outcomes. METHODS: We established surveillance for gastroenteritis outbreaks in 2001, and analyzed data on outbreaks occurring from 1 July 2002 through 30 June 2008 to estimate the incidence in Australian LTCFs and residents. We summarized outbreaks by mode of transmission and etiological agent. We used negative binomial regression to examine variation in the number of fecal specimens collected in outbreaks-a marker of investigation intensity. RESULTS: During surveillance, 3257 (52%) of 6295 outbreaks of gastroenteritis and foodborne disease in Australia were reported in LTCFs. These outbreaks affected 84,769 people, with 1577 people hospitalized and 209 deaths. There were 0.19 (95% confidence interval, 0.14-0.26) residents affected per 1000 bed days and 16.8 (95% confidence interval, 12.4-22.7) outbreaks per 100 LTCFs annually. LTCF outbreaks were most commonly transmitted from person to person. Only 43 (1.3% ) of 3257 outbreaks were foodborne, although 47 (6.4%) of 733 residents were hospitalized and 20 (2.7%) of 733 died. Norovirus was responsible for 1136 (35%) of all 3257 outbreaks. Higher numbers of fecal specimens per outbreak were collected in 4 Australian States, in later years of surveillance, and where the etiology was identified. CONCLUSIONS: Norovirus outbreaks spread from person to person are common in LTCFs, although clinicians should be alert for foodborne outbreaks with more serious consequences. There is a need to identify effective infection control measures to assist facilities in managing outbreaks of gastroenteritis.

Evaluation of Campylobacter infection surveillance in Victoria.

Campylobacter infection is a notifiable infectious disease in Victoria and with more than 6,000 cases notified annually, it is the second most commonly notified disease after chlamydia. The objectives of Campylobacter infection surveillance in Victoria are to monitor the epidemiology of Campylobacter infection, identify outbreaks, initiate control and prevention actions, educate the public in disease prevention, evaluate control and prevention measures, and plan services and priority setting. An evaluation of the system was undertaken to assess performance against its objectives, identify areas requiring improvement and inform a decision of whether Campylobacter infection should remain a notifiable infectious disease. The surveillance system was assessed on the attributes of data quality, timeliness, simplicity and acceptability using notifiable infectious diseases data and interviews with doctors who had failed to notify, and laboratory and public health staff. The evaluation found that the system collects core demographic data with high completeness that are appropriately reviewed, analysed and reported. In 2007, 12% of Campylobacter isolates were subtyped and only one to 3 outbreaks were identified annually from 2002 to 2007. Fifty-four per cent of cases were notified by doctors and 96% by laboratories, although nearly half of laboratory notifications were not received within the prescribed timeframe. Half of the surveyed non-notifying doctors thought that Campylobacter infection was not serious enough to warrant notification. The Campylobacter surveillance system is not fully satisfying its objectives. Investment in the further development of analytical methods, electronic notification and Campylobacter subtyping is required to improve simplicity, acceptability, timeliness and sensitivity.

Hepatitis a outbreak epidemiologically linked to a food handler in Melbourne, Victoria.

Hepatitis A is caused by the hepatitis A virus (HAV). Transmission occurs by the faecal-oral route, either by direct contact with an HAV-infected person or by ingestion of HAV-contaminated food or water. Hepatitis A outbreaks are uncommon in Australia. In 2008, Victoria experienced an outbreak of hepatitis A due to an infected food handler.

Obligations to report outbreaks of foodborne disease under the International Health Regulations (2005).

Every year, Australia identifies 2-3 outbreaks associated with imported foods. To examine national authorities' obligations under the International Health Regulations (2005), we reviewed outbreaks in 2001-2007 that implicated internationally distributed foods. Under these regulations, 6 (43%) [corrected] of 14 outbreaks would have required notification to the World Health Organization.