key: cord-0050825-h686sxnf
authors: Dey, Rafik; Ashbolt, Nicholas J.
title: Legionella Infection during and after the COVID-19 Pandemic
date: 2020-09-23
journal: nan
DOI: 10.1021/acsestwater.0c00151
sha: b0cbc163b9fa32b9765ac2916009c6450b7df0b7
doc_id: 50825
cord_uid: h686sxnf

nan

T here were two key lessons from the past devastating influenza pandemics (The 1918 "Spanish flu ", 1957, 1968, and 2009 ). The first is that most fatalities were due to bacterial co-infections. 1, 2 Reports of co-infection with respiratory pathogens in the current coronavirus pandemic are also on the increase throughout the world. 3 Recently, Zhou and colleagues reported that 50% of patients with COVID-19 who died had secondary bacterial infections. 4 Legionella and COVID-19 co-infection has been also described in patients, which can be fatal if untreated. 3, 5 Legionella is a waterborne bacterium that is responsible for Legionnaires' disease (LD), a severe pneumonia that occurs most frequently in susceptible persons, and those with comorbid conditions or immunosuppression. Legionella grows best in building water systems that are not well maintained, with Legionnaires' disease outbreaks most often reported for hotels, long-term care facilities, and hospitals. 6 In fact, the bacteria can cause community and nosocomial acquired pneumonia, with some 85% being sporadic cases. Up to 50% of sporadic cases of hospital-acquired pneumonia are caused by legionellae, and LD most commonly occurs after inhalation of Legionella-containing aerosols from showerheads, certain medical equipment (e.g., respiratory equipment), cooling towers, hot tubs, hydrotherapy equipment, or decorative fountains. 7 During the current worldwide pandemic, we suggest that patients with COVID-19 should be screened for Legionella; this is particularly important because the signs and symptoms of both infections are similar. 8 The second lesson learned is that the mortality rate and severity scores were higher after the pandemics. 9, 10 COVID-19 infections can predispose patients to Legionella co-infections associated with subsequent waves of infections and consequently pose a serious threat to high-risk COVID-19 patients after the peak(s) of the pandemic, which can lead to an increase in disease severity and mortality.

Cases and outbreaks due to legionellae are expected to continue to be a major health burden as they were prior to the COVID-19 pandemic. 11 Exposure to these agents is particularly problematic, especially after building closures or reduced operations with fewer people returning to full-time building operations. The reduced consumption of water can cause water stagnation in building water systems, increasing the risk for growth and spread of Legionella and its natural environmental reservoirs, free-living amoebae. 8, 12 In addition, the warm season also brings with it the risk of LD, because risk factors (use of air conditioners, spray parks/ fountains, etc.) increase when weather is warm and humid. 13 It will remain important for people to continue to take prudent steps to protect themselves and follow the recommendations specific to reopening after prolonged shutdowns. 14−16 As described in the new Centers for Disease Control and Prevention guidance, the LD threat also applies to hot tubs, water fountains, sprinkler systems, and millions of water cooling towers atop commercial buildings. 14 Ideally, as was previously implemented during the H1N1 influenza pandemic, 17 new recommendations for the post-COVID-19 pandemic period will be important for preventing the consequences of bacterial pneumonia co-infections and avoiding unexpected increases in mortality.

Public Health (ProvLab), Alberta Health Services, Edmonton, AB T2N 4W4, Canada; orcid.org/0000-0002-3853-0096 Complete contact information is available at: https://pubs.acs.org/10.1021/acsestwater.0c00151

The authors declare no competing financial interest.

This work was supported by Alberta Innovates (Grant 201300490), Alberta, Canada.

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