May 24, 2018

Taking a Strand

WQP Managing Editor writes about DNA testing for Legionnaires' source detection in her June 2018 editorial letter

WQP Managing Editor Amy McIntosh's June editorial letter

On any given evening you can find me on my couch consuming some kind of true crime content, from podcasts to Netflix specials and everything in between. If I’ve learned anything from the hours I’ve spent absorbing these stories, it’s that forensic technology—and more specifically, DNA—is somewhat of a miracle science when it comes to solving crimes.

This technology recently was an asset in tracking down the elusive Golden State Killer, and, according to a study in the Journal of Environmental Health, it also can be an asset in determining the source of Legionnaires’ disease. For crime fighters, this forensic technology offers the ability to match DNA with criminals or their relatives. For the water industry, it offers a method of identifying the source of Legionnaires’ disease significantly quicker than the traditional bacterial culture.

The methods used in both instances is called polymerase chain reaction (PCR), in which DNA fragments are run through a thermocycler, producing multiple copies of the DNA for analysis. The process takes just a few hours, compared with the several days necessary for a bacterial test.

Unlike bacterial tests, the PCR method cannot determine whether the Legionella in a water sample is dead or alive, but it can detect its presence, which is helpful during outbreaks.

The study’s authors know this from experience. During a 2014 outbreak in New York City, water from a building’s cooling tower was tested using the PCR method, and Legionella was determined to be present. The cooling tower was shut down, and days later the bacterial test confirmed the Legionella bacteria in the cooling tower was alive and the source of the outbreak. The test was used on a larger outbreak in 2015, again correctly identifying the source.

The researchers, including Christopher Boyd, general manager of building water health for North America at NSF Intl. and former assistant commissioner of environmental sciences and engineering for the NYC Department of Health and Mental Hygiene, believe use of this technology is imperative.

“In an outbreak investigation, the ability to identify and mitigate possible sources of exposure is critical to preventing more people from becoming infected,” Boyd said in an NSF press release. “By using PCR, we were able to mitigate risks days earlier than if we had relied on traditional culture methods.”

When it comes to crime, prevention is always the goal. Likewise in the water realm, having a detailed building water management plan is vital in preventing health issues.

“Very often in these outbreaks, health officials don’t know the source of exposure that is making people sick,” Boyd said in the release. “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.”

About the author

Amy McIntosh | Managing Editor | [email protected]

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