MARSHALLTOWN, Iowa — More cases of Legionnaires’ disease have been confirmed in Marshalltown.

Last week Iowa Health and Human Services announced it was investigating a cluster of Legionnaires’ disease in Marshalltown. On Thursday, Iowa HHS said that since August there have been 21 confirmed cases of the disease and one death. As of Monday, the number of confirmed cases in Marshall County had jumped to 30.

Legionnaires’ disease is caused by Legionella bacteria. According to Iowa HHS, the disease thrives in warm water environments and typically spreads through the inhalation of aerosolized water droplets like mist.

Iowa HHS says that most people considered healthy don’t get sick after being exposed to the bacteria. However, those who are 50 or older, have a weakened immune system, or have chronic respiratory conditions are more likely to fall ill.

Symptoms of Legionnaires’ disease include:

• Fever
• Cough
• Shortness of breath
• Muscle aches
• Headaches
• Chest pain
• Gastrointestinal symptoms such as nausea or diarrhea

Anyone with these symptoms in the Marshalltown area is encouraged to visit their primary health care provider. Iowa HHS says that the disease can be effectively treated with antibiotics when diagnosed early.

Iowa HHS, the Marshall County Public Health Department, and the CDC continue their investigation into the disease cluster.