Despite it being 50 years since Legionnaires’ disease was first discovered, people are still contracting it and dying from it. In scary fact, it seems like more cases are being found with each passing year. Most recently, a woman died and over 70 other people were infected after staying at the Sheraton Atlanta Hotel in July of 2019. And here’s a few harrowing statistics: between the years 2000 and 2017, reports of Legionnaires' disease has increased over 500 percent in the United States and each year over 6,000 people are infected with the disease with 250 people dying from the infection. What exactly is—or perhaps isn’t—going on?
As we covered in a previous post about a subsidized housing building in Harlem where 50 people in the surrounding area were hospitalized with Legionnaires' Disease and 2 died after inhaling microscopic droplets of water contaminated with Legionella Pneumophila, the disease can easily spread if ineffective filtration technologies are employed. That particular outbreak was connected to the housing project's improperly filtered cooling tower, similar to what transpired when the disease was first discovered in 1976 at the American Legion convention in Philadelphia. We now know that this dangerous bacteria can be commonly found in fresh water all over the world – making preventing outbreaks a difficult challenge. Other man-made water systems such as hot tubs, misters, fountains, hot water tanks, and even the complex plumbing systems in big buildings can also grow and spread Legionella.
Building owners and managers aren’t the only ones responsible for preventing Legionnaires' Disease. Regulations that require the implementation of a comprehensive water management program need to become more stringent and sophisticated. Commercial buildings that have miles of pipe where water may sit for long periods of time must be efficiently maintained to prevent Legionella growth. But current water treatment practices do not effectively address these waterborne bacteria, and even though the EPA has issued drinking water regulations, there are no requirements for testing of Legionella and no regulatory limit.
Legionella grows very well in water distribution and re-distribution systems. The pathogens grow in biofilm on pipe walls which trap nutrients from water flows and protect the thriving bacterial community from disinfectants. Once biofilms are formed, pathogens are released into the drinking water, and chlorine treatments intended to remove biofilm also strip large quantities of bacteria from the pipe walls which eventually flow into downstream water tanks.
Therefore, waterborne infections can only be significantly reduced if a concerted effort is made to address water distribution systems. One effective way to minimize this growth is to maintain a high level of chlorine throughout the distribution system. However, disinfection by-products—formed when high quantities of chlorine react with organics—are also dangerous. The only sensible solution, then, is to filter the organics out of the water before adding the chlorine. The state of New York has among the lowest requirements for disinfectant residual in the nation, and the result is insufficient chlorine levels in many sections of the water distribution system, but acceptable disinfection by-products. It is in this water distribution system with very low levels of chlorine that Legionella bacteria can flourish. Is it coincidental that the implementation of disinfection by-product regulations in the United States occurred over the same timeframe as a four-fold increase in the incidence of Legionnaires’ Disease?
As we start to better assess outbreaks like the ones in Washington Heights and Atlanta, responsible building owners and operators will need to seek expert consultation on the necessary protections for all places where bacterial growth can collect — and infect.
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