LegionellaInfectionDid you know that there was an unexplained spike in Legionnaire’s disease (pneumonia caused by Legionella pneumophila) during the 2009 H1N1 flu pandemic?

Since the flu season is rapidly approaching, I thought I would review what Legionnaire’s disease looks like. Yes, they will have a fever, cough, and pneumonia on CXR. These patients are generally pretty sick and almost always need hospitalization. What makes it unique? The trick is to look for extrapulmonary findings, which help to distinguish it from other atypical pneumonias. Relative bradycardia is a sure tip.

Why do we want to differentiate it from other pneumonias?

Legionnaire’s disease requires reporting to your state’s health department to help track for outbreaks.


Adapted from 1
Go to the ALiEM Cards site for more resources.

More information on Legionellosis from the CDC website.

1.
Cunha B. Legionnaires’ disease: clinical differentiation from typical and other atypical pneumonias. Infect Dis Clin North Am. 2010;24(1):73-105. [PubMed]
Michelle Lin, MD
ALiEM Editor-in-Chief
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD

@M_Lin

Professor of Emerg Med at UCSF-Zuckerberg San Francisco General. Founder of ALiEM @aliemteam #PostitPearls https://t.co/7v7cgJqNEn
Michelle Lin, MD