In Marshall County, Iowa, a sudden surge in Legionnaires’ disease cases has gripped the local community and drawn the attention of state and federal health officials. Over the span of just a few weeks, the number of confirmed cases has soared, raising both public concern and a flurry of investigative activity aimed at uncovering the root cause of the outbreak.
According to the Iowa Department of Health and Human Services (HHS), as of September 12, 2025, there have been 40 reported cases of Legionnaires’ disease in the county. The outbreak, which first came to light in early September, initially involved 21 infected individuals and, tragically, one death. Reverend Bernard "Bernie" Grady, a retired Catholic priest, remains the only reported fatality linked to the cluster as of the most recent update.
Legionnaires’ disease, as explained by the Centers for Disease Control and Prevention (CDC) and Iowa HHS, is a severe form of pneumonia caused by Legionella bacteria. The bacteria thrive in warm water environments and are typically spread through the inhalation of aerosolized water droplets. Common sources include cooling towers, hot tubs, and decorative fountains—places where water can become mist and be breathed in. Importantly, health officials emphasize that the disease is not contagious; it does not spread from person to person, which distinguishes it from many other respiratory illnesses.
The timeline of the outbreak is as striking as the numbers themselves. The Iowa HHS first announced the cluster in Marshall County earlier this month, with 21 cases and one death. Just days later, the count rose to 30, then 34, and by Tuesday, September 12, it had reached 40. This rapid increase has left residents anxious and demanding clear answers from public health authorities. The local Marshall County Public Health Department, alongside state officials and the CDC, has been working around the clock to investigate the outbreak’s source and prevent further spread.
Despite the intensity of the investigation, officials have yet to pinpoint the exact source of the Legionella bacteria responsible for the outbreak. On September 12, 2025, Marshalltown Water Works officials addressed growing concerns by stating unequivocally that the town’s treated drinking water is not the source. This reassurance, reported by KCCI, aimed to calm fears about the safety of the municipal water supply, though the search for the true origin continues.
Health officials are urging residents and business owners to remain vigilant about maintaining clean water systems, especially those that can produce mist or aerosolized water. The importance of regular cleaning and disinfection of hot tubs, cooling towers, and decorative fountains has been underscored repeatedly in public advisories. For those who may be at higher risk—such as individuals with weakened immune systems, chronic respiratory conditions, smokers, and people aged 50 and older—the warnings carry particular weight.
The symptoms of Legionnaires’ disease can be deceptively similar to other forms of pneumonia or respiratory infections, making early recognition critical. According to the Iowa HHS and CDC, common symptoms include fever, cough, shortness of breath, muscle aches, headaches, chest pain, and gastrointestinal symptoms like nausea or diarrhea. Officials have been clear: anyone experiencing these symptoms should seek medical care immediately. “Untreated, Legionnaires’ disease can be deadly,” health authorities have warned, pointing to the importance of prompt diagnosis and treatment.
The ongoing outbreak in Iowa is not an isolated event. This summer, New York experienced a significant outbreak of Legionnaires’ disease that resulted in seven deaths and 114 confirmed cases, as reported by KCCI. These incidents highlight the persistent risk posed by Legionella bacteria and the need for ongoing vigilance in monitoring water systems, particularly as climate patterns shift and infrastructure ages.
While the investigation in Marshall County remains active, the collaborative response from the Iowa HHS, Marshall County Public Health Department, and CDC underscores the seriousness with which public health officials are treating the situation. The CDC’s involvement brings additional expertise and resources to the table, including advanced laboratory testing and epidemiological support. Yet, the process of identifying the precise source of a Legionnaires’ outbreak is often painstaking. It can involve testing dozens of potential sites, from commercial cooling towers to residential water heaters, and requires cooperation from both public and private sectors.
For the residents of Marshall County, the uncertainty has been unsettling. Community members have expressed frustration and concern, particularly as the case count continued to rise over the past week. According to Metro News reports, local officials have faced mounting pressure to provide answers and actionable guidance as the investigation unfolds.
Despite the anxiety, health officials have consistently emphasized that most healthy people exposed to Legionella do not become ill. The disease primarily affects those with underlying health conditions or compromised immune systems. Still, the tragic death of Reverend Grady serves as a sobering reminder of the potential severity of the illness and the critical importance of public health vigilance.
In the meantime, the Iowa HHS has encouraged residents to stay informed through official channels and to consult the department’s website for the latest updates and guidance. The agency has also provided educational materials on Legionnaires’ disease, including prevention tips and advice for maintaining safe water systems.
As the investigation continues, one thing is clear: the Marshall County outbreak has put a spotlight on the importance of water safety, public health preparedness, and the need for rapid response in the face of emerging infectious disease threats. The lessons learned here will likely inform future efforts to prevent and respond to Legionnaires’ disease outbreaks, both in Iowa and across the country.
For now, local health officials, state agencies, and the CDC remain committed to identifying the source of the outbreak and protecting the health of Marshall County residents. Their work continues, even as the community waits for answers and hopes for an end to the alarming rise in cases.
