Test to rapidly identify Legionnaires’ disease designed by researchers

April 10 (UPI) — A DNA test allowed New York City health officials to rapidly identify the source of a Legionnaires’ disease outbreak, leading researchers to urge its widespread adoption.

New York City health officials identified the source of a Legionnaires’ disease outbreak in 2014, and then again during a larger outbreak in 2015, within hours of specimen collection by using a DNA test method called polymerase chain reaction. The researchers findings and recommendations were published in the April issue of the Journal of Environmental Health.

Legionnaires’ disease is a severe form of pneumonia that occurs from inhaling water droplets from manmade water systems contaminated with Legionella bacteria. In 1976, an outbreak of pneumonia caused 34 deaths at a 1976 American Legion Convention in Philadelphia, leading to the infection for this type of pneumonia to be named Legionnaire’s disease.

“In the United States, we have a very low tolerance for engineered systems to kill people,” Christopher Boyd, who led New York’s response to the 2014 Legionnaires’ outbreak as then-assistant commissioner of environmental sciences and engineering, said in a NSF press release. “We don’t allow elevators to fall and we expect fire sprinkler systems to work. So why is it that we continue to accept that failures in the maintenance of engineered water systems are addressed only when public health officials respond to significant increases in Legionnaires’ disease cases? There needs to be a paradigm shift among building owners, facility managers and public health officials — these outbreaks are preventable and the trigger for corrective action should no longer be sick and dead people.”

Nine in 10 outbreaks can be prevented with more effective water management, according to the Centers for Disease Control and Prevention. The CDC reported the number of people with Legionnaire’s quadrupled from 2000 to 2014. There are about 20 outbreaks reported each year, with 5,000 people diagnosed and about 10 percent fatalities.

“In an outbreak investigation, the ability to identify and mitigate possible sources of exposure is critical to preventing more people from becoming infected,” Boy said. “Our approach likely helped prevent more people from getting sick, because we were responding much sooner.”

In the test, fragments of DNA are run through a machine called a thermocycler, which heats and cools the sample, producing multiple copies of these DNA fragments in a few hours. By amplifying them, it makes them easier to analyze the samples.

The standard method of bacterial culture generally takes five to 10 days for a lab to detect the presence of Legionella bacteria.

“By using PCR, we were able to mitigate risks days earlier than if we had relied on traditional culture methods,” said Boyd, who is now general manager of Building Water Health for North America at NSF International, an independent, nonprofit public health and safety organization.

In late 2014, he and his team at the New York City Department of Health and Mental Hygiene suspected the outbreak of eight Legionnaires’ cases from a building’s cooling tower.

PCR water samples from the tower confirmed the presence of Legionella in a single day and the city ordered the cooling tower shut down and disinfected. Days later, results from a bacterial culture confirmed the bacteria was alive.

Then in 2015, they successfully investigated a much larger outbreak of Legionnaires’ disease that killed 16 people and sickened more than 100. A cooling tower also was confirmed as the source.

As a result, New York City instituted rules for the registration and oversight of all cooling towers.

“Very often in these outbreaks, health officials don’t know the source of exposure that is making people sick,” Boyd said. “It is critical that public health officials have an inventory of significant sources of risk and detailed response plans to speed the response to an outbreak.”

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