��vlog Investigates: Marshall County cases of Legionnaires' disease rise as hunt for elusive source continues

LITTLE BIT. STACEY. THANKS, ZANE. RIGHT NOW, STATE HEALTH OFFICIALS ARE TRYING TO FIGURE OUT WHAT IS CAUSING MORE CASES OF LEGIONNAIRES DISEASE IN MARSHALL COUNTY. THERE HAVE NOW BEEN 30 CONFIRMED CASES AND ONE DEATH. THE DISEASE SPREADS BY INHALING CONTAMINATED WATER DROPLETS. AT THIS TIME, A SOURCE OR SOURCES HAVE NOT BEEN IDENTIFIED. ��vlog CHIEF INVESTIGATIVE REPORTER SUZANNE BEHNKE TALKED WITH A PURDUE UNIVERSITY SCIENTIST ABOUT HOW YOU CAN PROTECT YOURSELF FROM EXPOSURE. SUZANNE. STACEY. THE CHARACTERISTICS OF THE LEGIONELLA BACTERIA CAN MAKE IT HARD TO TRACK. SO PROFESSOR KATELYN PROCTOR TELLS ��vlog INVESTIGATES THAT THERE ARE A FEW WAYS TO REDUCE EXPOSURE. SEARCHING FOR A SOURCE OF LEGIONNAIRES DISEASE. SOUNDS A LITTLE LIKE HIDE AND SEEK. WE CAN BE IN, LIKE, INVESTIGATING SYSTEMS AND IN ONE BUILDING IN THE SYSTEM HAS A LEGIONNAIRES PROBLEM AND THE NEXT DOOR BUILDING DOES NOT. YOU KNOW, LIKE IT’S VERY. OR ONE FLOOR OF A HOSPITAL HAS A PROBLEM AND THE NEXT FLOOR DOES NOT. PROFESSOR KATELYN PROCTOR SAYS THE BACTERIA THAT CAUSES THIS ILLNESS SEEMS TO LIKE THE WARMER TEMPERATURES IN LATE SUMMER AND EARLY FALL. THAT’S WHEN MORE CASES APPEAR. THE IOWA DEPARTMENT OF HEALTH AND HUMAN SERVICES CONFIRMS AT LEAST 30 CASES IN MARSHALL COUNTY SINCE AUGUST. ONE PERSON HAS DIED, SO THERE’S A LOT OF DIFFERENT POSSIBILITIES HERE AT THIS POINT THAT I HOPE THE INVESTIGATION NARROWS IT DOWN. PROCTOR SAYS. INVESTIGATORS WILL LOOK FOR A PARTICULAR STRAIN OF LEGIONELLA. THESE THINGS TAKE TIME TO ACTUALLY CONFIRM THAT THINGS ARE THE THINGS THAT INFECTED PEOPLE. AND, YOU KNOW, YOU DON’T WANT TO COME OUT AND SAY THE WHOLE WATER SYSTEM IS INFECTED IF LIKE, AGAIN, JUST BECAUSE YOU FIND LEGIONELLA IN THE SYSTEM DOESN’T MEAN THAT IT’S THE SAME THAT’S GETTING PEOPLE SICK OR, OR YOU COULD FIND LEGIONELLA IN YOUR SHOWER, BUT IT’S ACTUALLY FROM THE COOLING TOWER THAT PEOPLE ARE GETTING SICK. SO FAR, THERE’S BEEN NO SIGN OF BACTERIA IN MARSHALLTOWN’S WATER TREATMENT FACILITY. WE LEARNED THAT THIS AFTERNOON. PROCTOR DID SHARE SOME WAYS TO LIMIT EXPOSURE, INCLUDING RUNNING THE HOT WATER IN A SHOWER FOR 30S OR SO BEFORE GETTING IN THE SHOWER. SHE ALSO SAYS HOT WATER HEATERS COULD BE TURNED UP TO 140°F. BUT TO TAKE CARE WHEN DOING THAT SO YOU DON’T GET SCALDED. HEALTH OFFICIALS WANT TO STRESS LEGIONNAIRES DISEASE IS NOT CONTAGIOUS. IT TAKES BETWEEN 2 AND 10 DAYS AFTER BEING INFECTED TO SHOW SYMPTOMS. THAT CAN ALSO MAKE IT HARD TO FIND A SOURCE. SYMPTOMS WOULD LOOK LIKE A HEADACHE, FEVER AND MUSCLE ACHES, AMONG OTHERS, AND HEALTH OFFICIALS HAVE SAID IF YOU HAVE PNEUMONIA LIKE SYMPTOMS TO SEEK MEDICAL HELP. ��vlog INVESTIGATES ASKED THE STATE HEALTH DEPARTMENT AND THE CDC IF THEY ARE WORKING ON INVESTIGATING THE SOURCE. THE STATE HEALTH DEPARTMENT SAYS IT’S WORKING WITH FEDERAL PARTNERS, BUT D

Updated: 4:53 PM CDT Sep 9, 2025

Editorial Standards ⓘ

��vlog Investigates: Marshall County cases of Legionnaires' disease rise as hunt for elusive source continues

Updated: 4:53 PM CDT Sep 9, 2025

Editorial Standards ⓘ

Searching for a source of Legionnaires' disease sounds a little like hide and seek.State health officials are trying to figure out what's causing more cases of the illness in Marshall County where, as of Tuesday, there have been 34 confirmed cases, including one death.The disease spreads by inhaling bacteria-contaminated water droplets.At this time, a source or sources have not been identified."There's a lot of different possibilities here at this point, and I hope the investigation narrows it down," said Caitlin Proctor, assistant professor at Purdue University.The nature of Legionella, the bacteria that cause the illness, can make it tricky to track down. Legionella seems to prefer late summer and early fall, when temperatures are warmer. It can also be fickle in its location."We can be in investigating systems and, and one building in the system has a Legionnaires' problem, and the next-door building does not ... or one floor of a hospital has a problem and the next floor does not," Proctor said.Another factor that can lengthen the investigation is looking for and testing for the strain that is causing the illnesses.So far, there's been no sign of the bacteria in Marshalltown's water treatment facility, said its director, Zach Maxfield.Proctor did share some ways to limit exposure.They include running the hot water in a shower for 30 seconds or so before getting in the shower.She also said hot water heaters could be turned up to 140 degrees Fahrenheit.Health officials want to stress that Legionnaires' disease is not contagious. It takes between two and 10 days after being infected to show symptoms. That can also make it hard to find a source.Symptoms include headache, fever and muscle aches, among others. Health officials have said that if you have symptoms to seek medical help.How will officials find the source of the outbreak? According to Proctor, most city water treatment systems will kill the Legionella bacteria, but cannot stop it from growing further down the water distribution system in areas like cooling towers or individual service lines. "Even in the best managed systems, it happens," Proctor said. "It's kind of a natural thing... It's bound to grow there." But once the investigating authorities find the bacteria, it's still not guaranteed to be the source causing the sickness. If a growth of the bacteria is found, authorities will need to consider that the bacteria may have originated further up the service system.There are also potential causes for the outbreak besides water contamination, such as large air-conditioning systems, open bodies of water, and more that authorities will consider in the investigation. Watch: Learning more about Legionnaires' diseaseWatch: Legionnaires' disease cases up to 30 in Marshall County, HHS says» Subscribe to ��vlog's YouTube page» Download the free ��vlog app to get updates on the go: Apple | Google Play

MARSHALLTOWN, Iowa —

Searching for a source of Legionnaires' disease sounds a little like hide and seek.

State health officials are trying to figure out what's causing more cases of the illness in Marshall County where, as of Tuesday, there have been 34 confirmed cases, including one death.

The disease spreads by inhaling bacteria-contaminated water droplets.

At this time, a source or sources have not been identified.

"There's a lot of different possibilities here at this point, and I hope the investigation narrows it down," said Caitlin Proctor, assistant professor at Purdue University.

The nature of Legionella, the bacteria that cause the illness, can make it tricky to track down. Legionella seems to prefer late summer and early fall, when temperatures are warmer. It can also be fickle in its location.

"We can be in investigating systems and, and one building in the system has a Legionnaires' problem, and the next-door building does not ... or one floor of a hospital has a problem and the next floor does not," Proctor said.

Another factor that can lengthen the investigation is looking for and testing for the strain that is causing the illnesses.

So far, there's been no sign of the bacteria in Marshalltown's water treatment facility, said its director, Zach Maxfield.

Proctor did share some ways to limit exposure.

They include running the hot water in a shower for 30 seconds or so before getting in the shower.

She also said hot water heaters could be turned up to 140 degrees Fahrenheit.

Health officials want to stress that Legionnaires' disease is not contagious. It takes between two and 10 days after being infected to show symptoms. That can also make it hard to find a source.

Symptoms include headache, fever and muscle aches, among others. Health officials have said that if you have symptoms to seek medical help.

How will officials find the source of the outbreak?

According to Proctor, most city water treatment systems will kill the Legionella bacteria, but cannot stop it from growing further down the water distribution system in areas like cooling towers or individual service lines.

"Even in the best managed systems, it happens," Proctor said. "It's kind of a natural thing... It's bound to grow there."

But once the investigating authorities find the bacteria, it's still not guaranteed to be the source causing the sickness. If a growth of the bacteria is found, authorities will need to consider that the bacteria may have originated further up the service system.

There are also potential causes for the outbreak besides water contamination, such as large air-conditioning systems, open bodies of water, and more that authorities will consider in the investigation.

Watch: Learning more about Legionnaires' disease

Watch: Legionnaires' disease cases up to 30 in Marshall County, HHS says