Meningococcal Surveillance Australia: Reporting period 1 April to 30 June 2025

The reference laboratories of the Australian National Neisseria Network report data on invasive meningococcal disease (IMD) confirmed by culture and/or molecular techniques for the Australian Meningococcal Surveillance Programme (AMSP). Culture-positive cases and molecular-based diagnoses are defined as IMD by the Communicable Diseases Network Australia National Guidelines for Public Health Units.1 Data contained in the quarterly reports are restricted to a description of the number of cases by jurisdiction and serogroup, when known. The content of the quarterly reports was expanded in 2024 to include antimicrobial resistance (AMR) data for ceftriaxone, penicillin, ciprofloxacin and rifampicin. IMD AMR data was previously only reported annually in the AMSP Annual Report. The AMSP has a programme-specific quality assurance process. Some minor corrections to data in Table 1 may be made in subsequent reports if additional data are received. IMD notifications in Australia for the first six months of 2025 were consistent with the corresponding period of 2024 (Table 1),2 but lower than the 85 IMD notifications reported at quarter two year-to-date (ytd) in 2019 (prior to the SARS-CoV-2 pandemic).3 In quarter two 2025 ytd, there were 59 notifications of IMD nationally, of which 55/59 (93%) had the serogroup determined at the time of reporting. Notably, the predominance of N. meningitidis serogroup B (MenB) IMD continued in 2025, accounting for 82% of notifications (45/55) ytd, higher than reported in quarter 1 2025 (72%). In contrast, between 2019 and 2021, the proportion of IMD attributable to MenB was 50–62%.4 The number of notifications of IMD attributed to MenW and MenY remain small, and no further MenA or MenC IMD cases were reported in Australia in quarter two of 2025 (Table 1). Antimicrobial susceptibility testing data, on the 39 IMD diagnosed by culture ytd, detected two penicillin-resistant isolates, one from Western Australia (quarter one) and one from Victoria (quarter 2), both identified as MenB IMD. All 39 IMD isolates were susceptible to ceftriaxone and there was no resistance detected to ciprofloxacin and rifampicin. A full analysis of laboratory-confirmed cases of IMD in each calendar year is contained in the AMSP annual report published in Communicable Diseases Intelligence.