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Legionnaires' disease has tripled nationwide: study

Legionnaires’ disease is far from a New York-only issue. Cases have tripled nationwide, and it's an incipient global problem as the planet warms.
New York City Mayor Bill de Blasio holds up a chart documenting the cases of Legionnaires' disease while speaking to reporters at Lincoln Hospital in the Bronx borough of N.Y. on Aug. 4, 2015. (Photo by Seth Wenig/AP)
New York City Mayor Bill de Blasio holds up a chart documenting the cases of Legionnaires' disease while speaking to reporters at Lincoln Hospital in the Bronx borough of N.Y. on Aug. 4, 2015.

Savor the blast of an air conditioner or down a glass of tap water and you might catch them: Legionella bacteria. 

The pellet-shaped micro-organisms are the source of Legionnaires' disease, a rapidly escalating public health threat, according to researchers. They live in warm, damp spaces, where they sometimes multiple into deadly airborne threats, as they have in New York City this summer.

Since July 10th, nearly 100 people have caught the bug in the Bronx. At least eight of them have died. It’s the worst outbreak in the city’s history. But reported cases of Legionnaires’ disease have more than tripled since 2001, according to a new study in the Journal of Public Health Management Practice. Worse, the country is poorly prepared to prevent a still greater outbreak, the authors argued. 

RELATED: 97 Sick, 8 dead in NYC Legionnaires' outbreak: Officials

That study and another published in March also suggested that the latest epidemic may signal an incipient global problem, possibly tied to climate change. “Legionnaires’ disease should now be added to the IPCC’s list of important climate sensitive health issues,” Japanese researcher Ryota Sakamoto argued in a recent paper published by the World Health Organization.

The IPCC, or Intergovernmental Panel on Climate Change, has already warned that hotter temperatures and heavier rains could stir up killers from the edges of civilization. That’s recognized to include well-known diseases like dengue fever, West Nile virus, and malaria. Sakamoto believes Legionnaires’ disease deserves the same level of scrutiny.

The number of incidents is certainly on the rise. There were 3,522 cases nationwide in 2009, according to the most recent detailed data from the Centers for Disease Control. That’s more than double the count from a decade earlier. And preliminary data shows a continued spike to 4,548 cases in 2013, the more recent year that numbers are available.  

New York City has seen a similar rise. The number of increased 230% from 2002 to 2009, with the greatest number in high-poverty neighborhoods, according to an October study in the CDC journal Emerging Infectious Diseases. The CDC now estimates that there are between 8,000 and 18,000 cases a year, nationwide. The Occupational Safety & Health Adminstration, meanwhile, provides an estimate of up to 50,000 cases annually.  

Exact counts are impossible to come by, because they depend on reporting from local hospitals and doctors. But the increase is mirrored in Canada and Europe, and it raises the question of whether longer, warmer summers and more torrential rainfall has spread the disease.

The rise has been particularly visible in the mid-Atlantic, northeast, and Great Lakes Region, where the worst clusters have been associated with cruise ships, health club hot tubs, decorative fountains, supermarket produce mist, old pipes, new air conditioners, and the machinery atop city buildings. Basically, the disease is possible anywhere there is warm standing water, blown or misted into the air, or leaked into sinks, taps or showers. The disease can’t spread person-to-person like a cold—but it is airborne.      

CDC officials have attributed the increase to an older, more vulnerable population and better record-keeping. But Dr. David N. Fisman, a professor at the Dalla Lana School of Public Health at the University of Toronto, told NBC New York that he doubted the increase was the result solely of improved testing. After all, he said the rise is linear and across all regions of the United States. 

The disease’s first appearance shocked health experts in the bicentennial summer of 1976, decimating an American Legion Convention in Philadelphia. Hundreds of World War II veterans became mysteriously ill, suffering fevers, coughs, and muscle aches. Doctors thought it was a normal outbreak of pneumonia or the flu. But then the disease invaded the lungs, and the veterans started dying: 34 of them in all.

“We don’t know what we’re dealing with,” said Pennsylvania’s health commissioner at the time. Federal health officials rush to investigate. Without an authoritative explanation, the media crackled with lies, rumors and half-truths. It was the KGB! It was the CIA!

Within a year an enterprising team of health researchers had isolated the problem: millions of bacterium, a fraction of a millimeter long, and covered in a fuzzy sweater of flagella. In the years since, they’ve come to understand the disease occurs naturally in soil, puddles, and mountain lakes. The trouble comes when it pools in humanity’s many modern contraptions, gathering into an unnaturally severe threat.

They’ve also figured out how to treat the disease with antibiotics, reducing the fatality rate to less than 5% if caught early. But Dr. Ruth Berkelman, a professor at Emory University’s Rollins School of Public Health, is worried. She's lead author of the new paper, the one that found a tripling in the number of reported cases. In the same report, she and co-authored revealed that there is no single set of widely accepted guidelines for primary prevention of legionnaires' disease. It's also been more than two decades since the last national review of the disease and the nation's level of readiness to stave off a wider problem.

 “Legionellosis deserves a higher public health priority,” she and her co-authors concluded. At the cost of dozens of sick people, the epidemic of New York City may have just given it one.