New paper: Legionella DNA markers in tap water in Flint, Michigan

The Flint Water Crisis garnered national and international media coverage of elevated levels of lead in the water delivered to consumers’ taps. When the city of Flint began using the Flint River as its drinking water source without the addition of a corrosion inhibitor beginning in April 2014, the corrosive new water began to leach lead from service lines, lead solder, and brass plumbing fixtures. Our team predicted, based on our recently published laboratory studies, that the lack of corrosion control would also increase the likelihood of Legionnaires’ disease.  Early in 2016, it was acknowledged that two clusters of Legionnaires’ disease cases did, in fact, occur in the Flint area during the time Flint River water was used. A total of 92 cases and 12 deaths were recorded in Genesee County from June 2014 to October 2015, making it one of the largest outbreaks in US history.

Details on this study can be found at:

A new study published by our team at Virginia Tech demonstrates that tap water samples collected from large hospital buildings in Flint during fall of 2015 contained DNA markers for Legionella spp. and L. pneumophila in much greater abundance than is typically observed in surveys of U.S. tap water. This provides another line of evidence that the water switch in Flint likely contributed to the Legionnaires’ disease outbreak. Importantly, the paper highlights the critical role of municipal water supply and management in protecting public health against Legionnaires’ disease.  We hypothesize that the corrosive water contributed to the outbreak by releasing iron from pipes, which in turn accelerated decay of chlorine and served as a nutrient for Legionella. Based on our findings and other lessons learned from Flint, we advocate for coordination between utilities and building owners in monitoring and controlling Legionella at the tap. In the future, as urged in the Governor’s Task Force Report, municipalities should keep their eyes open to potential problems with Legionella when switching water sources.

The article is open access and may be obtained at

2 thoughts on “New paper: Legionella DNA markers in tap water in Flint, Michigan

  1. It has been my position that the “source” of the treated water inFlint had little to do w/ the initial outbreak in 2014. The corrosivity of the treated water after the switch may have exacerbated and contributed to the continuation in 2015. However, it was the mechanics of the “switching” that generated the initial outbreak in 2014 as in the process of “switching” a “dead-leg” condition was incorporated into the distribution flow and provided the initial and substatial inoculating dose of the distribution system as well as assist in the establishment of secondary reservoirs w/in individual building/systems that were vulnerable; McLaren Hospital is a glaring example of this. process. This is the “dead-leg” scenario.

    The “dead-leg” scenario is also the most likely cause of the outbreak in NYC/Bronx, summer of 2015 as well. The cooling tower at the Opera House Theater Hotel was but one of the resultant SECONDARY reservoirs established and NOT wholly responsible for the entire outbreak

  2. (continuation)
    What is most needed is to establish adequate protocol to identify and prevent the inclusion of “dead-leg” conditions when making such changes, if not done, we may witness a familiar occurrence when the ultimate connection to the Kerignondi consortium supply source is finalized.

    Let us investigate and learn from these examples and establish the appropriate protocols to avoid similar outbreaks in the future.

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