Officials: Marshalltown Legionnaires' Outbreak Linked to Cooling Towers
Understanding the Legionnaires’ Disease Outbreak in Marshalltown
A recent outbreak of Legionnaires’ disease in Marshalltown has raised concerns among residents and public health officials. The illness, which claimed one life and affected at least 34 others, is believed to be linked to cooling towers found in large buildings. This revelation came from state officials who presented their findings to the Marshall County Board of Supervisors.
Dr. Matthew Donahue, the state epidemiologist with Iowa Health and Human Services, emphasized that while there isn’t a definitive source, the evidence points toward cooling towers as the most likely cause. “We don’t have a smoking gun,” he stated during a meeting on September 10. “But we’re focusing on this area as the primary suspect.”
The outbreak was first identified in late August and quickly spread through north central Marshalltown. Public health agencies at the county, state, and federal levels responded urgently. According to Donahue, the pattern of cases suggests an airborne transmission rather than household exposure.
What Is Legionnaires’ Disease?
Legionnaires’ disease is a severe form of pneumonia caused by the Legionella bacteria. These bacteria are naturally present in natural water sources such as lakes, rivers, ponds, soil, and even gardens. However, they thrive in warm, stagnant water, which can accumulate in various systems within buildings.
The bacteria spreads when contaminated mist is inhaled, but it cannot be transmitted from person to person. Symptoms include cough, fever, shortness of breath, headaches, muscle aches, and sometimes nausea, diarrhea, or confusion. The incubation period ranges from two to 14 days, and the disease can be fatal, particularly for adults over 50, individuals with chronic lung diseases, or smokers.
The individual who died had underlying health conditions, according to Iowa HHS. Early detection and treatment with antibiotics can significantly improve outcomes.
The Role of Cooling Towers
Cooling towers, commonly found on the roofs of industrial or commercial buildings, play a crucial role in removing heat from air conditioning systems. These devices circulate water to cool down the building, but if not properly maintained, they can become breeding grounds for Legionella bacteria.
“Any device that heats water and sprays it or humidifies it could be a risk for Legionella,” Donahue explained. If the bacteria enter these systems, they can multiply in the warm water and be released into the air through evaporation.
So far, 10 cooling towers in Marshalltown have been identified as potential sources. Nine had been tested by the time of the board meeting, with one more scheduled for testing later that day. At least four of the towers had already undergone chemical disinfection, and the rest were expected to follow. The samples are being cultured at the State Hygienic Lab in Iowa City, with results potentially available within the week.
Steps Being Taken to Address the Outbreak
Marshall County Public Health Director Sydney Grewell has been actively involved in the response, collecting water samples from cooling towers herself. She noted that while the testing process is not difficult, it requires local knowledge and connections. “It helps to be Marshalltown local and grow up here to have those connections with people,” she said.
Grewell also mentioned that some businesses already had systems in place to treat and monitor their cooling towers, while others pledged to increase maintenance efforts after the outbreak. She emphasized the importance of implementing formal water management plans, which are recommended nationally and supported by CDC toolkits.
Donahue urged businesses in Marshalltown to ensure they have a water management plan in place. “That’s a main ask that we have now,” he said. “Businesses should establish formal water management plans that they’re following very closely.”
Public Risk and Community Response
Despite the outbreak, officials stress that the public risk remains low. The first cases were reported on August 24, and as more infections were confirmed, Iowa HHS issued a clinician advisory on September 3 and a public press release the following day.
Donahue defended the timeline of alerts, noting that identifying a local cluster required several days of interviews and patient tracing. “I think this was the system working exactly as it should,” he said. “And I don’t know if it would have been possible to have done anything earlier.”
Zach Maxfield, general manager of Marshalltown Water Works, addressed concerns about drinking water safety. He clarified that Legionnaires’ disease is not spread through drinking water. “If it was us, there’d be way more than 31 cases,” he said. His agency continues daily testing and aims to keep the public informed.
Residents are advised to consult their doctors if they experience pneumonia-like symptoms. Early detection and treatment are critical in managing the disease. Overall, the community remains vigilant, with ongoing efforts to prevent future outbreaks.
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