New York City Outbreak: What Is Legionnaire's Disease?

At least seven people in New York City have died and 86 have been infected in an outbreak of Legionnaires' disease. The illness can cause high fevers and pneumonia.

But despite the current outbreak, most people in the region aren't at any increased risk of getting Legionnaires'. The disease is not communicable between people, and only those with weakened immune systems or other health impairments tend to fall ill. In addition, most people who do get Legionnaires' can be treated with antibiotics.

From its source to its treatment, here are some of the most important things to know about the disease and the current outbreak. []

1. What is Legionnaires' disease?amoebae. However, occasionally these bacteria may infect people, and can cause cough, high fever,  and death, said Dr. Victor Yu, a researcher at the Special Pathogens Laboratory at the University of Pittsburgh.

2. Is there treatment?

3. Who is at greatest risk of Legionnaires' disease?diabetes, said Janet Stout, a microbiologist and the director of the Special Pathogens Laboratory.

"It essentially infects older people, and the most common are elderly men who smoke cigarettes," Yu said.

In the current outbreak in New York, everyone who has fallen ill had some underlying medical condition or health problem, according to the New York City Department of Public Health.

4. When was Legionnaires' disease first identified?

5. How is it spread?

"The majority of cases of Legionnaires' disease occur as a result of the warm water system," Stout said.

The most common sources of outbreaks are drinking water systems in hospitals, hotels and other institutional facilities, she said. In those instances, people typically acquire the infection after breathing in a little bit of fluid, such as can happen when drinking something or taking a shower. Nowadays, more and more hospitals sanitize their water to prevent the spread of Legionnaires' disease, Yu said.

Most of these outbreaks last a long time, but involve only a few sporadic cases.

But when "explosive" outbreaks hit many people at once, water-cooling towers are often the culprits, Stout said. The current New York City outbreak is just such an explosive outbreak, as was , that sickened 170.

"These devices provide Legionella bacteria with everything they need to grow," Stout said. The towers provide a warm, wet environment, while filters suck in dirt from the environment that provides perfect food for the bacteria to multiply. The towers also give off an aerosolized mist that can transmit the disease to people passing by, she added.

In one unusual case, people contracted the disease from the water-mist devices that are used to keep produce fresh at the supermarket, said Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee.

6. What is the cause of the current outbreak in New York?cooling towers in the Bronx have tested positive for Legionella, and . However, it is common for water sources to test positive for Legionella, so the test result does not definitively point to these towers as the culprit of an outbreak, Yu said. For instance, 30 to 70 percent of three-story apartment buildings may test positive for Legionella, but do not necessarily cause disease, he said.

To be sure that the cooling towers were indeed the source of the New York outbreak, researchers will need to test the molecular fingerprint of the bacteria from patients, and compare it with environmental samples from the cooling towers. That should take about a week, Stout said.

7. Can officials stop the current outbreak?

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