Flint Water Still Under Investigation For Legionella

In April 2014, the city of Flint, Michigan, made the switch from their main water source supplier, the Detroit Water and Sewerage Department, to the Flint River, which has highly corrosive water. This switch led to wide-spread damage to the city’s water distribution system, and the damage is said to have caused increased incidence of elevated blood lead levels in children throughout the city. In addition, two major clusters of Legionnaires’ disease were reported in the summer months that followed the switch in water suppliers. These clusters resulted in 91 illnesses and 12 deaths.

During a press conference at the ASM Microbe 2016 meeting in Boston, Massachusetts, lead researcher from the Flint Water Study team, Otto Schwake, PhD, from the department of Civil and Environmental Engineering at Virginia Tech, stated that Legionnaires’ disease is “the leading cause of drinking-water-related outbreaks,” in America and most other developed countries, with a 9% mortality rate.

In an interview with Contagion, Dr. Schwake explained the factors that contribute to the proliferation of Legionella in buildings.

In October 2015, the city of Flint switched its main water supply back to the City of Detroit Water, and enforced a corrosion control plan, which has contributed to a steady improvement in the quality of the water in Flint. Nonetheless, Flint residents are still encouraged to drink, and cook with, bottled water or tap water that is filtered using lead-removing systems.

Research conducted by the Flint Water Study team has also revealed that DNA marker levels for Legionella in the city’s water supply have substantially decreased since the water supply switch in October 2015. However, according to Dr. Schwake, some sampled regions still contained pathogenic forms of the bacteria, including L. pneumophila even as recently as March 2016.

Since residents are cautioned against the use of tap water, the age of the water that resides in the pipes has contributed to its contamination. To solve this issue, the city implemented a program in May 2016 to encourage city residents to flush water through the pipes to clean them by suspending the cost for this water usage.

Dr. Schwake discussed the possibility of leftover Legionella from the Flint River occuring in Flint sewage pipes with Contagion.

Previously, the water was only tested for Legionella DNA, which failed to distinguish between live and dead cells. However, Dr. Schwake’s research team has managed to collect large amounts of cultured environmental samples, as well as Legionella isolates from Flint. These samples may aid in tracking Legionnaires’ transmission throughout the city.

The team plans to return to Flint this summer (2016) to analyze Legionella levels in the water. They believe that bacterial levels should not be as high as during the 2015 outbreak, due to the change in water supply, higher chlorine residuals, lower temperatures, and optimized corrosion control.

The Virginia Tech Institute for Critical Technology and Applied Science has funded this project in collaboration with the National Science Foundation, and the Alfred P. Sloan Foundation. Research findings were presented at ASM Microbe 2016 in Boston, Massachusetts.