Legionnaires' Disease Outbreak

Legionnaires’ disease symptoms include cough, fever, and shortness of breath. Most people with this serious type of pneumonia need care in a hospital, and 1 in 10 die. About 5,000 people are diagnosed with Legionnaires’ disease. Legionnaires’ disease most often affects older adults, current or former smokers, those with chronic lung disease, and those with weak immune systems.

People can get Legionnaires’ disease by breathing in small water droplets contaminated with Legionella germs from sources like decorative fountains, water used for showering, hot tubs, and cooling towers. Legionella grows in the warm water that does not have disinfectant to kill germs. Legionella can make people sick when the germs grow in the water and spread in droplets small enough for people to breathe in.

Outbreaks of Legionnaires’ disease are on the rise, and most occur in hotels, long-term care facilities, and hospitals. 9 in 10 Legionnaires’ disease outbreaks investigated by CDC were caused by problems that could have been prevented with more effective water management.

CDC investigated the first outbreak of Legionnaires’ disease, a serious lung infection (pneumonia), in 1976.

  • According to CDC The number of people with Legionnaires’ disease grew by nearly 4 times from 2000–2014.

  • Legionnaires’ disease is deadly for about 10% of people who get it.

  • 9 in 10. CDC investigations show almost all outbreaks were caused by problems preventable with more effective water management.

What causes the Legionnaires’ disease outbreaks that CDC investigates?

  • About 1 in 2 (48%) are due to more than one of the following problems.

  • About 2 in 3 (65%) are due to process failures, like not having a Legionella water management program.

  • About 1 in 2 (52%) are due to human error, such as a hot tub filter not being cleaned or replaced as recommended by the manufacturer.

  • About 1 in 3 (35%) are due to equipment, such as a disinfection system, not working.

  • About 1 in 3 (35%) are due to changes in water quality from reasons external to the building itself, like nearby construction.

Where do people get Legionnaires’ disease?

  • CDC investigations of building-associated outbreaks show the most common places for getting the disease are hotels, long-term care facilities, and hospitals. Cruise ships are another place where Legionnaires’ disease outbreaks can happen.

  • In these types of buildings, the most likely sources for spreading water droplets contaminated with Legionella include:

  • Showers and faucets.

  • Cooling towers, which are parts of large centralized air conditioning systems.

  • Hot tubs.

  • Decorative fountains and water features.

What Can Be Done
Healthcare providers can:
  • Tell patients if they are at increased risk for pneumonia, including Legionnaires’ disease, and to seek care quickly if they develop symptoms of pneumonia.

  • Test for Legionnaires’ disease in people with serious pneumonia, especially those requiring intensive care or who recently stayed in a healthcare facility or hotel or on a cruise ship. Use a urinary antigen test and a culture from a lower respiratory specimen (e.g., sputum).

  • Report positive Legionnaires’ disease lab tests to local public health authorities quickly.

The Federal government is:
  • Providing tools for building owners and managers to understand how to develop water management programs to reduce the risk of Legionnaires’ disease.

  • Working with health, academic, and industry partners to develop and evaluate guidelines and standards to prevent Legionnaires’ disease.

  • Working towards including Legionnaires’ disease prevention practices in national building and public health codes.

  • Improving healthcare for veterans by requiring plans for prevention of Legionnaires’ disease at Veterans Health Administration hospitals and long-term care facilities.

  • Tracking Legionnaires’ disease and responding to outbreaks to find the source and help prevent future infections.

State and local officials can:
  • Incorporate Legionella water management programs into licensing and accreditation requirements for healthcare facilities.

  • Consider changing building and public health codes to include Legionella water management programs.

  • Provide tools and information to help local building owners and managers carry out Legionella water management programs.

  • Investigate reports of Legionnaires’ disease promptly to prevent more people from getting sick.

Building owners and managers can:
  • Learn about and follow newly published standards for Legionella water management programs. http://bit.ly/1Ph3wQP

  • Determine if the water systems in their buildings are at increased risk of growing and spreading Legionella.

  • Develop and use a Legionella water management program as needed. www.cdc.gov/legionella/WMPtoolkit

  • Monitor and respond to changes in water quality.

Learn more about CDC’s Water management programs in buildings to help prevent outbreaks


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