Official State of Iowa Website Here is how you know
Iowa Department of Health and Human Services



Legionellosis is a disease caused by a bacterium. It causes two different forms of illness: Legionnaire’s Disease and Pontiac Fever. Legionnaire’s Disease is the more serious illness.

Legionellosis is reportable to the Iowa Department of Public Health by Iowa Administrative Code 641 Chapter 1.


Both Legionnaires' disease and Pontiac fever present with anorexia, malaise, muscle aches, headache and fever.  Abdominal pain and diarrhea are also common.  It will take between 2 to 10 days after being infected with this bacterium to show symptoms of Legionnaire’s Disease. Pontiac Fever takes 5 to 72 hours. Onset of symptoms can be rapid.

Pontiac fever is self-limited.  Patients recover spontaneously in 2-5 days without treatment.  

Legionnaires' disease is a more serious illness and requires treatment.  Symptoms progress to include:

  • Fever up to 105° F
  • Chills
  • Non-productive cough
  • Stomach pain
  • Diarrhea

Legionnaire’s Disease often turns into pneumonia and some people can die from this if not treated carefully.


Legionnaire’s Disease is caused by breathing in bacteria from sources of contaminated water. It is not spread person-to-person. This bacterium has been found in many different kinds of water systems, such as hot and cold-water taps and showers, creeks, ponds, whirlpool spas, cooling towers and evaporative condensers of large air-conditioning systems. Outbreaks have also been linked to decorative fountains, humidifiers, respiratory therapy devices and grocery store vegetable misters. These bacteria are more likely to reproduce in high numbers in warm, stagnant water and can be difficult to remove from a water supply.

Risk Factors

Not everyone exposed to legionella bacteria will become ill. You have an increased risk of becoming ill if you:

  • Smoke. Smoking damages the lungs and makes you more susceptible to all types of lung infections.
  • Have chronic lung diseases such as emphysema
  • Immunocompromised
  • Males become ill 2.5 times more than females
  • Adults >50 years old


  • If a water supply is thought to have caused disease in people, careful treatment of the water source is needed.
  • Stopping smoking reduces risk of this disease.
  • Hotels, cruise ships and other owners of whirlpool spas and decorative fountains should maintain them according to the manufacturer’s recommendations, have adequate levels of proper disinfectant at all times, and keep current on protocols for public health safety.
  • Tap water should not be used in respiratory therapy devices.


  • Legionnaire’s Disease is treated with antibiotics.
  • Pontiac Fever goes away on its own without treatment.


There were 44 cases of legionellosis reported to IDPH in 2021.

For more detailed information and statistics on all notifiable diseases, please see our current annual report located in the reports section of the CADE homepage.

Additional Resources


Public Health


Business and Childcare

Health Care Providers