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Legionnaires' Disease and Legionellosis: Information for Providers

Legionnaires' Disease Cluster on the Upper East Side

The NYC Health Department is currently investigating a community cluster of Legionnaires' disease in the Upper East Side neighborhoods of Carnegie Hill and Yorkville (ZIP codes 10028, 10128, and 10075). Current information on this outbreak can be found on the main Legionnaires' Disease page.

Clinicians should maintain a high index of suspicion for Legionnaires’ disease in any patient with pneumonia who currently lives or works in this area, or who has visited the area since late June, and should test and treat empirically for Legionella. Parents experiencing flu-like symptoms, such as fever, cough, or difficulty breathing, are advised to seek care immediately.

Health care providers in New York City are required to report confirmed cases of legionellosis to the NYC Health Department online through PRISM (preferred), through the Provider Access Line (PAL) at 866-692-3641, or by mailing or faxing a Universal Reporting Form (PDF).

Providers may also call the PAL for timely consultation regarding public health management of Legionnaires’ disease.

NYC Health Alert #18: Cluster of Legionnaires’ Disease in Carnegie Hill/Yorkville (PDF, July 2)
NYS and NYC Health Advisory #13: Legionellosis (PDF, June 1)

Legionnaires' Disease: Update for Healthcare Providers Webinar

The NYC Health Department invites healthcare providers to join our medical epidemiologists and outbreak investigators for a webinar on this cluster.

Thursday, July 16, at 8 a.m.
Register on Zoom

Legionellosis is a bacterial disease caused by Legionella species and includes several forms of illness:

Legionnaires' disease: pneumonia diagnosed radiographically or clinically
Pontiac fever: a milder, self-limiting illness without pneumonia that does not require antibiotic treatment
Extrapulmonary legionellosis: a rare infection outside the lungs (e.g., endocarditis, wound infection)

Epidemiology

Legionnaires’ disease occurs year-round in New York City, with increased incidence during the summer and early fall (June to October), and with 200 to 700 cases reported every year. Clusters and outbreaks are common in both community and health care settings.

The estimated case-fatality proportion for Legionnaires' disease is about 10% for community-acquired cases and 25% for healthcare-associated cases.

Clinical Presentation

Clinical suspicion for Legionnaires' disease should be elevated in patients presenting with pneumonia, especially those who report:

Residence in or recent travel to an area with an ongoing outbreak
Recent hotel stays or cruise ship travel
Recent exposure to hot tubs
Recent inpatient care at a health care facility
Residence in a congregate setting, such as a skilled nursing facility or long-term care facility

Risk Factors

People at higher risk for Legionnaires' disease include those who:

Are age 50 years or older
Previously or currently smoke or vape
Are living with chronic lung disease, an immunocompromising condition, systemic malignancy, or comorbid conditions such as diabetes or renal/hepatic failure

Testing

Diagnostic testing for Legionella includes respiratory culture, PCR, and urine antigen testing (UAT) and can be performed through most clinical and commercial laboratories.

Respiratory specimens for Legionella culture should ideally be collected before antibiotics are started, but antibiotics should never be delayed to obtain a specimen — cultures can still be ordered after antibiotics have begun.
Clinicians must specifically request that the specimen be cultured for Legionella (not a general respiratory bacterial culture), since this requires specialized media (buffered charcoal yeast extract [BCYE] agar).
Culture remains the gold standard: it is the only method that allows clinical isolates to be compared with environmental isolates to identify a potential source.
PCR and urine antigen testing offer faster turnaround but have limitations (see NYS and NYC Health Advisory #13: Legionellosis (PDF, June 1).

Treatment

Patients suspected or confirmed to have Legionnaire’s Disease should be treated with antibiotics with adequate Legionella coverage regardless of the need for hospitalization, using either:

A macrolide (e.g., azithromycin), or
A respiratory fluoroquinolone (e.g., levofloxacin)

Empiric treatment of community-acquired pneumonia in hospitalized patients should always include adequate coverage for Legionella and can then be tailored based on the results of diagnostic tests.

For detailed clinical guidance, see the American Thoracic Society/Infectious Diseases Society of America Guidelines for Diagnosis and Treatment of Adults with Community-Acquired Pneumonia.

Public Health Reporting

Health care providers and laboratories are required to promptly report legionellosis cases to the Health Department where the patient resides.

NYC Residents: Report to the NYC Health Department by calling the Provider Access Line (PAL) at 866-692-3641.

Laboratories should submit all confirmed Legionella isolates for serotyping and whole genome sequencing. Send isolates for NYC residents to the NYC Public Health Laboratory (PHL) using PHL eOrder. Select Legionella serotyping and send isolates to 455 1st Avenue, New York, NY 10016.