Rebound mortality rate of Legionella pneumonia in Japan.

Legionella pneumonia is a fatal disease caused by Legionella pneumophila, a bacterium belonging to the genus Legionella. The incidence of this disease has been increasing since 2005 and has continued to increase following the COVID-19 pandemic in Japan. Furthermore, Legionella pneumonia mortality rates have increased slightly since the pandemic due to some plausible reasons. The increased proportion of older patients with legionellosis might affect it because advanced age is a major risk factor for disease mortality. Additionally, physicians were focused on COVID-19 while examining febrile patients; therefore, they might have missed the early diagnosis of other respiratory infections, including Legionella pneumonia.