Marshalltown Legionnaires’ disease cases expand to 54

The number of Marshalltown residents diagnosed with Legionnaires’ disease continues to climb as local and state public health experts reported last week they are working to identify the source of the outbreak.

Since late August, the state has confirmed 54 cases of Legionnaires’ disease, and one person has died from the infection. Previously, health officials have said all of the cases are in residents who live in the north central part of the city. It is unclear if that still is true.

Legionnaires’ disease is caused by Legionella bacteria, which thrive in warm water and typically spread when a person inhales aerosolized water droplets.

Last week, State Epidemiologist Matthew Donahue told the Marshall County Board of Supervisors that public health officials believe the source of the outbreak is a cooling tower.

As of last Wednesday, Donahue and Marshall County Public Health Director Sydney Grewell said they had tested nine of the cooling towers they believed could be responsible for the outbreak. Donahue declined to identify the towers’ locations or the companies that operate them.

Donahue said state officials were asking businesses to disinfect their cooling towers, which will kill the Legionella bacteria and decrease the risk of it spreading further. As of last Wednesday morning, four had completed the disinfection process, and Donahue expressed confidence that the others would do the same.

Legionnaires’ disease is not contagious and most healthy people who are exposed do not get sick, state health officials said. The person who died as a result of the Marshalltown infection had underlying health conditions, the state reported.

The Iowa Department of Health and Human Services is working with health care providers in Marshalltown to advise them to test for Legionnaires’ disease if a patient who lives in Marshalltown or has spent time there develops pneumonia.

Symptoms of Legionnaires’ disease include:

People who are more likely to experience severe illness from Legionnaires’ disease include individuals 50 years and older, those with weakened immune systems, those with chronic respiratory conditions such as asthma and COPD, and smokers.