NYC health authorities reported an outbreak of 58 cases (2 deaths) with Legionnaires’ disease in Central Harlem from 25 July to 4 August. Specific cooling towers are probably the source of transmission, but investigations of clinical and environmental isolates (including whole genome sequencing) are still ongoing. People >50, smokers, with chronic lung disease and/or weakened immune system are at high risk.
Outbreaks linked to cooling towers have occurred in NYC in the past with the largest (138 cases) occurring between July and September 2015. A cooling tower is a specialized heat exchanger that removes heat from a system by circulating water and exposing it to the atmosphere, primarily through evaporative cooling. This cooled water is then recirculated back into the system, while the heat is dissipated into the atmosphere.
Legionella multiply especially in hot water systems, humidifiers, cooling towers, whirlpools and hydrotherapeutic facilities at water temperatures below 50°C.
Particularly at risk of severe illness are people older than 50, smokers, people with chronic lung disease diabetes, or weakened immune system such as transplant recipients and tumor patients.