Legionnaire's Disease Outbreaks Hit Minnesota and Washington

State health departments in Minnesota and Washington are on the alert after recent outbreaks of Legionnaire’s disease. With one person now dead in Minnesota and two dead in Washington due to these bacterial infections, local health officials are investigating these clusters.

According to the Centers for Disease Control and Prevention (CDC), Legionella bacteria can cause Legionellosis, a serious type of pneumonia, or lung infection. The bacteria are most commonly found in freshwater sources such as lakes and streams, but can spread to hot tubs, large plumbing systems, hot water heaters, cooling towers, and decorative fountains. While drinking infected water won’t cause Legionellosis, people become exposed to the bacteria and can develop pneumonia by breathing in tiny droplets of water containing Legionella. Aspiration of infected water—when it goes “down the wrong pipe” into the lungs instead of the digestive tract—can also lead to Legionnaire’s disease. Symptoms of the infection typically begin 2 to 10 days after Legionella exposure, and include cough, fever, muscle aches, shortness of breath, and headaches. About 1 in 10 individuals who become infected die due to complications. A milder and pneumonia-free infection with the bacteria is known as Pontiac fever, which has fewer symptoms and lasts less time. Legionella infections are typically treated successfully with antibiotics.

In the Minnesota town of Hopkins, a recent outbreak of Legionnaire’s disease has reached 17 confirmed cases. According to the Minnesota Department of Health, which is investigating this cluster, the outbreak began in early August. The DOH noted that about 50 to 60 cases are typically reported each year, but this new cluster of infections will push the reported cases for this year over the typical amount. While state health officials have yet to pinpoint the cause of this recent outbreak, they say that all 17 cases involve individuals who live in, work in, or have visited the town of Hopkins. Most of the cases have occurred in individuals 50 years of age or older and many of those infected have been hospitalized. On September 21, the outbreak claimed the life of an elderly patient, the first and only death so far in this Legionnaire’s disease cluster.

“We continue to investigate potential sources for the outbreak, but have not confirmed nor ruled out any at this point,” Minnesota Department of Health information officer Doug Schultz told Contagion. “However, every day that brings us new information, whether on cases or potential sources, brings us closer to finding the source. We have several lab results from case patients that match for a specific Legionella strain by DNA fingerprinting; we are hopeful that we may be able to find a matching strain in environmental samples from suspect sources. However, growing Legionella in the laboratory takes a long time, so we are still waiting on those results.”

In another ongoing investigation in Washington state, local health officials have confirmed six recent Legionella pneumonia cases at two different health treatment facilities. Doctors have diagnosed five patients at Seattle’s University of Washington Medical Center with Legionnaire’s disease. Two of those patients, both in their 50s, have died, in an outbreak believed to be linked to contamination inside a tower of the facility’s water system. In addition, heater-cooler units used there during heart surgeries tested positive for the presence of Legionella bacteria. Two of the four patients infected were exposed to these machines and one of them has died. However, officials at the hospital claim that because the patients were protected by ventilators and were not exposed to the devices during the incubation period, they have ruled out the heater-cooler units as the source of the outbreak. The medical center’s water system has since been flushed with chlorine and new filters have been installed on faucets and showers. One additional case of Legionnaire’s disease was also recently reported at Overlake Hospital Medical Center in Bellevue, Washington, though state health officials say the cases appear to be unrelated.

While there is no vaccine for Legionella infections, the CDC notes that local water testing and infrastructure management can greatly prevent outbreaks related to the bacteria. Proper maintenance and cleaning of hot tubs, large plumbing systems, fountains and other water systems can greatly reduce the risk of growing and spreading Legionella.