Jojy Cheriyan MD,MPH- July 30, 2015

The New York City health department reports that two patients have died and dozens have been sickened in an outbreak of Legionnaires' disease centered in South Bronx. Thirty-one cases of the flu-like disease have been reported since mid-July 2015 in the South Bronx.

Legionnaire's disease is a respiratory bacterial disease (pneumonia-like) that spreads through mist from water sources including air conditioning and cooling towers, and chance of death is 5% to 30%. City officials have said the city water supply is not at risk, but they urge people with symptoms to get tested at the earliest.

Symptoms of Legionnaires' disease are similar to those of pneumonia which makes it difficult to diagnose. Signs of the disease can include: a high fever, chills, cough and fatigue or weakness. Some people may also suffer from muscles aches and headaches. Symptoms usually begin 2 to 14 days after exposure.

The New York city health department continues to investigate by testing water from potential sources in the area.

It is not transmitted person to person. People get Legionnaires' disease when they breathe-in a mist or vapor (small droplets of water in the air) that has been contaminated with the Legionella bacteria. Outbreaks occur following the exposure of many individuals to a common source of the bacteria in the environment.

In 2012 two people at a hotel in downtown Chicago were killed after being diagnosed with Legionnaire's disease. An estimated 8,000 to 18,000 hospitalized cases of Legionnaires' disease occurs each year in the United States (according to CDC).

The bacteria got its name in 1976, when many people who went to a Philadelphia convention of the American Legion suffered from an outbreak of this disease, which was initially diagnosed as an unknown-type of pneumonia. Subsequently, the bacterium causing the illness was named Legionella pneumophila and the name of the illness was changed to Legionellosis or Legionnaires' disease.

Legionella bacteria naturally exist in the environment, usually in water. The bacteria grows best in warm water, and are most commonly found in water sources such as hot and cold water taps, hot water tanks, and water in air conditioning systems. They have also been found in misting systems, decorative fountains and whirlpool spas.

People most at risk of getting sick are older people, as well as people who smoke or drink heavily, or those who have chronic lung disease (like COPD).

People who have weak immune systems from diseases, such as cancer, diabetes or kidney failure are also likely to get sick from Legionella bacteria.

People who take drugs to suppress (weaken) the immune system (like after a transplant operation or chemotherapy) are also at high risk. The disease is treated with common antibiotics like Levaquin, Moxiflox, Erythromycin etc.