Legionellosis 2023: What does the data tell us?

The following article has been rewritten from information originally presented by the njbassociates.co.uk. You can find a link to the original article at the bottom of the page.

In late November 2024, the “Legionellosis in Residents of England and Wales: 2017 to 2023” report was published, providing detailed statistics on Legionella cases for 2023.

The data reveals that 603 cases were confirmed in England and Wales during 2023. Over 70% of these occurred in males, and more than 60% affected individuals aged over 60. Thirteen cases (approximately 2%) were linked to healthcare settings. The total number of cases exceeded those reported in 2022 and surpassed pre-pandemic levels of confirmed infections.

The report highlights that cases are more frequent from June to October, suggesting that systems struggle to cope with higher external temperatures—a concern likely to escalate as UK temperatures rise. This seasonal trend is consistent across the data from 2017 to 2023.

Figure 2 underscores the impact of age on susceptibility, with over 35% of cases occurring in individuals aged 70 and older. Comparatively, cases in those under 50 illustrate how age and associated health conditions increase vulnerability. This trend is further reinforced by data in Figure 7, which shows that over two-thirds of cases involve smokers or former smokers.

The challenges in diagnosing Legionnaires’ disease remain significant. The Urinary Antigen Test (UAT) is the most commonly used diagnostic tool, with over 3,000 tests conducted between 2017 and 2023, accounting for 64.7% of tests performed. In 2023, the UAT identified 576 cases of Legionnaires’ disease. While effective in detecting over 90% of reported cases, the limitations of this method raise concerns about undetected infections. This is reflected in the species distribution, with over 97% of cases linked to L. pneumophila.

The report also reviews travel-associated cases of Legionnaires’ disease. Cases linked to international travel have returned to pre-pandemic levels, which saw a significant decline during the COVID-19 pandemic. Meanwhile, cases associated with domestic travel within the UK have remained steady, averaging around 50 annually with a flat trend line from 2017 to 2023.

To see the full report click here.

If you or your company requires a pre-commission disinfection please contact Black Sheep.