Look out for Legionnaires’ Disease: 2023 Legionellosis Testing and Public Health Recommendations
This bulletin is being sent to local public health officers and nurses, Tribal health directors, infection preventionists, long-term care facilities, Wisconsin National Healthcare Safety Network (NHSN) users, and subscribers of the Division of Quality Assurance's Assisted Living Forum and Notifications and Updates lists.
This time of year, from summer through fall, is typically when an increase in legionellosis cases begins in Wisconsin. With warmer weather, people are more likely to be exposed to Legionella bacteria in aerosolized water droplets from showers, cooling towers (parts of large air conditioning systems), decorative fountains, hot tubs, and other human-made water systems.
We need your help with diagnosing and reporting cases of Legionnaires' disease to promptly determine sources of exposure to Legionella so that we can prevent further infections.
 Have a patient with pneumonia? You may need to test for Legionnaires’ disease.
Does your patient have a severe case of pneumonia? Do they have chronic underlying illnesses? Have they recently traveled? Have they had a recent potential exposure? Consider testing your patient for Legionnaires’ disease.
For a full list of situations in which you should test your patient for Legionnaires’ disease, visit the DHS Legionellosis webpage.
Order both a lower respiratory culture and a urinary antigen test.
When testing for Legionnaires’ disease, order both a lower respiratory culture and a urinary antigen test.
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Make sure you’re not missing some species and serogroups. Urinary antigen tests will only detect Legionella pneumophila serogroup 1, resulting in a missed opportunity to diagnose approximately 20% of all Legionnaires’ disease cases if not paired with a lower respiratory culture.
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Help us find the source of exposure. Lower respiratory cultures are very helpful in comparing the Legionella culture from patients to environmental samples.
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Don’t throw out lower respiratory specimens.
- Laboratories should not discard the sputum after a routine sputum culture for pneumonia if a Legionella culture or PCR has not been ordered, even if the patient has a positive urinary antigen test.
- Laboratories should not reject lower respiratory specimens for Legionella culture based on lack of white blood cells in the sample or contamination with other bacteria in the sample. Legionella can often be recovered on selective media.
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Send sputum to the Wisconsin State Laboratory of Hygiene for free PCR and culture testing.
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Legionella will not grow on standard media used for routine respiratory cultures. Legionella culture must be specifically ordered. See instructions for laboratories on how to ship specimens to the State Lab.
- You don’t need DHS approval for testing patients with positive urine antigen tests.
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Please report cases as soon as possible.
Legionnaires' disease is a Wisconsin Disease Surveillance Category II Disease. Report to the patient's local public health department electronically, through the Wisconsin Electronic Disease Surveillance System (WEDSS), by mail, or fax using an Acute and Communicable Disease Case Report, F-44151 or by other means within 72 hours upon recognition of a case.
For more information see the Case Reporting and Investigation Protocol (previously called EpiNet): Legionellosis, P-01895.
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Health care facility managers: You can prevent healthcare-acquired Legionnaires’ disease!
Legionnaires' disease can be prevented by minimizing growth in building water systems. One of the most effective ways to prevent healthcare-acquired Legionnaires’ disease is to implement a water management program compliant with American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Standard 188.
Resources
Thank you so much for your help preventing, diagnosing, and reporting Legionnaires' disease.
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