The Cardno ChemRisk View
Recent Outbreak of Legionnaire’s Disease in New York
Posted on behalf of the author, Yousuf Ahmad
An outbreak of Legionnaire’s disease in the South Bronx, New York, has resulted in two deaths and at least 46 cases since mid-July 2015. Legionnaire’s disease generally takes two to 10 days to develop after exposure to the Legionella bacterium. Initial symptoms include headache, muscle pain, chills and fever, followed by cough, shortness of breath, chest pain, and gastrointestinal symptoms including nausea and vomiting. New York City Mayor Bill de Blasio and Health Commissioner Dr. Mary T. Bassett have urged city residents to seek care if they believe they are experiencing symptoms as prompt treatment can help shorten the recovery period and prevent further health complications.
Legionnaire’sdisease is a respiratory infection that occurs when the bacterium Legionella is transmitted via aerosolized water sources. These water droplets containing the Legionella bacterium can come from mist from cooling towers, air conditioning systems, swimming pools or showers. The genus Legionella contains more than 50 species, about half of which have been associated with human infection. The Legionella pneumophila species in particular has been shown to fuse and replicate within macrophages and epithelial cells in the lung. Less than 5% of the people exposed to the bacterium develop Legionnaire’s disease, of which 10-15% of the cases can be fatal. A less severe, but more common form of infection, Pontiac Fever, is similarly caused by Legionella bacteria. However, the key difference between the two is that Legionnaire’s disease is accompanied with pneumonia.
As explained recently in the New York Times and elsewhere, investigators in the Bronx outbreak identified cooling towers as one potential source of the bacteria. In the article, Dr. Jay Varma, deputy commissioner for disease control at the New York City Department of Health and Mental Hygiene, stated that there were 15 cooling towers affected by this latest outbreak. However, Dr. Varma noted that the exact cause is yet to be determined as the cases were not clustered at a single site. The City of New York has a website that includes information regarding this disease, including how to identify symptoms.