Shigellosis in South East Metropolitan Melbourne, 1 January 2022 - 31 March 2023

Shigella is a notifiable condition in Victoria under the Public Health and Wellbeing Act. Since 24 October 2022, the South East Public Health Unit (SEPHU) has been managing these notifications for the south east region of Melbourne.

This study aimed to determine the demographics and risk factors for acquisition of shigellosis cases in the SEPHU catchment.

A review was performed of all shigellosis notifications within the SEPHU catchment during the period 1 January 1 2022 - 31 March 2023. De-identified information was collated from the Public Health Event Surveillance System (PHESS) for analysis of demographics, risk factors and antimicrobial resistance.

A total of 127 cases were notified: 51 were confirmed with culture, with the remaining 76 identified as probable cases through polymerase chain reaction testing. The greatest numbers of cases were within the 0-4 and 5-9 years of age categories (each 19/127; 15%), followed by the 30-34 years age group (18/127; 14%). The highest case numbers were recorded in the local government area (LGA) of Casey (30/127; 24%) while the highest rate across the 15-month study period, of 20.2 per 100,000, was from the Stonnington LGA. The most prominent primary risk factor was travel overseas (62/127, 49%) followed by contact between men who have sex with men (MSM) (16/127, 13%). Of confirmed cases, 61% (31/51) met the criteria for classification as critical antibiotic resistance (CAR) shigellosis.

This review found that the LGAs with high number and rates of cases are Casey, Greater Dandenong and Stonnington. However, the risk factors for acquisition differs in these areas, indicating a need for LGA-specific education in the diverse SEPHU catchment.