A recent Legionnaires’ disease outbreak in London has once again highlighted a critical truth about how this dangerous illness spreads—and, just as importantly, where it does not typically originate. According to the UK Health Security Agency (UKHSA), at least eight confirmed cases have been identified as of March 23, 2026, with an additional 13 cases under investigation. All confirmed cases share identical bacterial sequence types, suggesting a common environmental source rather than unrelated exposures. No Single Source Identified—But Patterns Are Clear Health officials have not yet identified a single exposure site. However, the investigation is focusing on environmental water systems,…