Recent increase in atypical presentations of invasive meningococcal disease in France

Invasive meningococcal disease (IMD) cases declined upon the implementation of non-pharmaceutical interventions (NPI) (social distancing and mask wearing) to control the COVID-19 pandemic but rebounded in 2022 in numbers with genotypical changes of the strains. We explored here associated modifications in the clinical presentations of IMD.

We conducted a retrospective descriptive study using the Database of the French National Reference Centre for meningococci and Haemophilus influnezae for IMD cases between 2015 and 2022. We scored serogroups, sex, age groups, clinical presentations and clonal complexes of the corresponding patients and isolates.

Non-meningeal forms of IMD increased significantly upon easing of NPI, such as bacteremic meningococcal pneumonia and bacteremic abdominal forms. They represented 6% and 8% of all IMD forms and were significantly linked to serogroups Y and W respectively, to older adults for bacteremic pneumonia and to young adults for bacteremic abdominal presentations. These forms were significantly associated with more early mortality and clonal complexes 23, 11 and 9316.

The increase in atypical IMD forms may lead to higher burden of IMD due to delayed diagnosis and management. Updating prevention may be needed through by adapting the current vaccination strategies to epidemiological changes.