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.

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.

Sesame seed products contaminated with Salmonella: three outbreaks associated with tahini

In November 2002, the first of three outbreaks of Salmonella Montevideo infection in Australia and New Zealand was identified in New South Wales, Australia. Affected persons were interviewed, and epidemiologically linked retail outlets inspected. Imported tahini was rapidly identified as the source of infection. The contaminated tahini was recalled and international alerts posted. A second outbreak was identified in Australia in June-July 2003 and another in New Zealand in August 2003. In a total of 68 S. Montevideo infections, 66 cases were contacted. Fifty-four (82%) reported consumption of sesame seed-based foods. Laboratory analyses demonstrated closely related PFGE patterns in the S. Montevideo isolates from human cases and sesame-based foods imported from two countries. On the basis of our investigations sesame-based products were sampled in other jurisdictions and three products in Canada and one in the United Kingdom were positive for Salmonella spp., demonstrating the value of international alerts when food products have a wide distribution and a long shelf life. A review of the controls for Salmonella spp. during the production of sesame-based products is recommended.

Hepatitis E infections, Victoria, Australia

In the first half of 2004, acute hepatitis E virus infections diagnosed in Victoria, Australia, increased 7-fold. Of the interviewed patients with highly reactive serologic results, 90% reported recent clinically compatible illness and overseas travel. The increase is compared with a background of exposure in countries in which hepatitis E is endemic.