Legionnaires' disease has been on the upswing across Michigan with cases confirmed in 33 Michigan counties including Wayne, Oakland and Macomb, state health officials said Monday.

There have been 135 cases of the disease by July 1, compared with 107 cases by the same time last year, according to the Michigan Department of Health and Human Services. 

The cases include 24 in Detroit, 19 in Macomb County, 16 in Oakland and 11 in Wayne County. 

Legionnaires' disease or legionellosis, is a type of pneumonia caused by legionella bacteria. The pathogen is found naturally in fresh water lakes and streams but also can be present in man-made water systems. Outbreaks have been linked to cooling towers, whirlpool spas and decorative fountains, which can be breeding grounds for the pathogen if not properly cleaned.

Transmission occurs when mist or vapor containing the bacteria is inhaled; it doesn't spread person-to-person.  

An epidemic of Legionnaires' disease in Flint and Genesee County in 2014 and 2015 sickened 91 people, including 12 who died. Some scientists have linked the outbreak to changes made to the city's water system in April 2014. The health department  has claimed McLaren Flint Hospital was the source. The  health system denies that claim. Several state officials face criminal charges related to the outbreak.  

Twenty-four of this summer's cases have been confirmed since July 1, and another 13 are pending confirmation. State health officials are coordinating with local health departments to inform them about the increase and share information about testing and treatment.

The uptick is part of a national trend, health officials said. The disease is most common in summer and early fall when warm, stagnant waters create an ideal environment for the bacteria. 

Symptoms of the respiratory infection are similar to other kinds of pneumonia and include fever, shortness of breath and coughing, the Centers for Disease Control and Prevention says. A milder form of legionellosis, Pontiac fever, is an influenza-like illness without pneumonia that resolves on its own.

Most healthy individuals do not become infected after exposure to Legionella.  People most at risk are the  elderly or those who have weakened immune systems, as well as those who have recently spent time in a hot tub, health care facility or hotel. 

Information on Legionella and Legionnaires’ disease can be found on the Centers for Disease Control and Prevention website.


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