Michigan Launches Statewide Investigation After Increase In Legionellosis Cases

July 06, 2019 - 12:04 pm

LANSING (WWJ) - The Michigan Department of Health and Human Services is coordinating with local health departments across the state to investigate an increase in cases of legionellosis this summer.

To date in 2019, there have been 140 confirmed cases of legionellosis reported in 38 counties, compared to 135 confirmed cases during the same timeframe in 2018. Confirmed cases include 19 in Oakland County, 16 in Wayne County, 13 in Macomb County, 11 in Genesee County and 10 cases each in the City of Detroit and Kent County.

Health officials say the increase corresponds with national increases in legionellosis -- a respiratory infection caused by Legionella bacteria. The infection is most common in the summer and early fall when warming, stagnant waters present the best environment for bacterial growth in water systems.

Legionellosis occurs in two forms:

  • Legionnaires' disease -- an infection with symptoms that include fever, cough and pneumonia
  • Pontiac fever -- a milder form of legionellosis; an influenza-like illness without pneumonia that resolves on its own

Health departments are working to inform healthcare providers of the increase in cases and share information regarding testing and treatment.

Legionella bacteria are found naturally in fresh water lakes and streams but can also be found in man-made water systems. Potable water systems, cooling towers, whirlpool spas and decorative fountains offer common environments for bacterial growth and transmission if they are not cleaned and maintained properly. Warm water, stagnation and low disinfectant levels are conditions that support growth in these water systems.

Transmission to people occurs when mist or vapor containing the bacteria is inhaled. Legionellosis does not spread person to person. Risk factors for exposure to Legionella bacteria include:

  • Recent travel with an overnight stay
  • Recent stay in a healthcare facility
  • Exposure to hot tubs
  • Exposure to settings where the plumbing has had recent repairs or maintenance work

Most healthy individuals do not become infected after exposure to Legionella. Individuals at a higher risk of getting sick include the following:

  • People over age 50
  • Current or former smokers
  • People with chronic lung disease
  • People with weakened immune systems from diseases, such as cancer, diabetes or liver or kidney failure
  • People who take immunosuppressant drugs

Individuals with any concerns about Legionnaires’ disease or exposure to the Legionella bacteria should talk to their healthcare provider. More information can be found on the Centers for Disease Control and Prevention website.