Legionnaires' disease in Scotland
Surveillance report 2023

About this release

This release by Public Health Scotland (PHS) reports Scottish Legionnaires' disease data for 2023. Last year's report was the first published since the pandemic and covered the years 2017 to 2022. Legionnaires' disease surveillance data reporting is now annual in Scotland, reports were previously biennial. We are continuing to develop this report and currently have plans for a review of relevant Legionella guidance.

Main points

• Case numbers and incidence increased in 2023 with 54 cases, an incidence of 9.9 per million population. This continues an increasing trend in Legionnaires' disease since 2021. The latest report from European Centre for Disease Prevention and Control (ECDC) describes increasing trends across European Union/European Economic Area countries to 2021
• This is the highest number of cases and incidence observed since 2012, with no outbreaks, common sources, exposures or links identified.
• Unlike previous years, most cases during 2023 were community-acquired (59.3%).
• Legionnaires' disease cases peaked in quarter three (July to September) of 2023, driven mainly by community-acquired cases. The highest number of community-acquired cases during 2023 was recorded in quarter three.
• During 2023, 94.4% of cases were aged 40 years and older; comparable to the age distribution reported for Europe by ECDC in 2021, where 91% of Legionnaires' disease cases were in those aged 45 years and older.
• In 2023, there were three reported deaths in Legionnaires' disease cases equating to a case fatality rate (CFR) of 5.6%. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

This figure is a line chart which shows annual Legionnaires’ disease cases in Scotland from 2000 to 2023. A peak in cases was observed in 2012 when there was a large Legionnaires’ disease outbreak in Edinburgh. Number of cases remained stable from 2017 to 2019, dropping in 2020 and 2021. As for 2023 where case numbers were at 54 cases, these are of the highest since 2013, when there were 48 cases.

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Annual total of cases of Legionnaires' disease in Scotland, 2000- 2023

Background

Legionella infections are notifiable under the Public Health etc (Scotland) Act 2008. Public Health Scotland (PHS) has conducted enhanced surveillance of Legionnaires' disease alongside the Scottish Microbiology Reference Laboratory (SMiRL) since 1994 collecting demographic data, clinical and microbiological information, and risk factors. This allows us to identify and monitor trends, detect outbreaks, identify potential sources of infection and inform measures to reduce the public health risk. Surveillance in Scotland is integrated with that of the rest of the UK.

Further information

The next release of this publication will be August 2025.