Legionellosis is the medical name for the infections caused by Legionella bacteria — principally Legionnaires’ disease, a severe pneumonia caused by Legionella pneumophila, and the milder Pontiac fever. It is not foodborne: infection comes from inhaling contaminated aerosols from cooling towers, evaporative condensers, showers, hot tubs or nebulizers — never from eating or drinking. Prevention centres on water-system design (avoiding dead legs and stagnation), temperature control (hot water above 60°C, cold below 20°C), disinfection (chlorine, chlorine dioxide) and monitoring — matters of concern for food factories with large water systems, bakeries’ humidifiers and produce wash lines.