In Australia and New Zealand, late outbreaks of an A(H3N2) variant virus termed subclade K extended the 2025 influenza season. Subclade K viruses were genetically and antigenically distinct from the 2025 vaccine A(H3N2) strain A/Croatia/10136RV/2023 (H3N2)-like virus and previously circulating subclade J viruses. Subclade K viruses have since been detected in over 34 countries and appear to have spread globally, except in South America. It is thus likely that they will further expand during the northern hemisphere winter 2025/26 season.

Trichophyton indotineae is an emerging dermatophyte increasingly detected in the United Kingdom, often with antifungal resistance. We identified 363 cases between January 2017 and August 2025, with 310 cases (85%) since January 2023. Cases were mostly concentrated in major urban centres and most affected individuals were working-age adults, frequently reporting South Asian ethnicity. The importance of international importation vs domestic transmission remains unclear. Implementing enhanced surveillance would help to identify risk factors and transmission routes to focus prevention efforts.

In 2025, an unprecedented number of autochthonous chikungunya transmission events occurred in mainland France. One of the largest outbreaks took place in Bergerac (south-west France). By 27 October, 100 locally acquired cases were identified. They had symptom onsets between June and October. Our data suggest that door-knocking surveys and vector control measures assisted in slowing the virus spread. Autochthonous outbreaks of mosquito-borne diseases are expected to become more frequent with climate change, so improving outbreak control is crucial.

Ralstonia mannitolilytica is a rare emerging, multidrug-resistant, opportunistic pathogen known to cause nosocomial outbreaks associated with hospital water sources and medical devices. In June 2024, the microbiology laboratory of Lausanne University Hospital alerted the Infection Prevention and Control Unit following the detection of R. mannitolilytica in clinical samples from two intensive care unit (ICU) patients. This triggered a comprehensive epidemiological investigation, including extensive environmental sampling and whole genome sequencing of the isolates. Between May and June 2024, R. mannitolilytica was detected in three ICU patients. Activation of the Swissnoso network led to the identification of an additional case in a rehabilitation centre. Environmental investigations traced the source to commercial cosmetic water mist sprays used for patient care. The sequences confirmed a genetic match between patient and spray isolates, prompting the immediate withdrawal of this product. This nosocomial outbreak of R. mannitolilytica revealed an unexpected and seemingly innocuous source of contamination – water mist sprays – highlighting the importance of considering cosmetics products used in patient care and questioning their use in patients with risk factors, such as those in ICU or with immunosuppression.