Public Health Scotland has published the first presentation of Scottish Legionnaires’ disease data since the COVID-19 pandemic, covering the years 2017 to 2022, which shows a slight increase in cases and incidence in the most recent year.

Legionnaires’ disease is a severe form of pneumonia caused by legionella bacteria, which can be acquired if tiny droplets of water containing the bacteria are inhaled.

Symptoms can include a cough, difficulty breathing, chest pain, and a high temperature, often accompanied by vomiting and diarrhoea, and, in some cases, confusion.

The surveillance report indicates that case numbers were stable in 2017 (35), 2018 (37) and 2019 (36), before reducing during the COVID-19 pandemic years of 2020 (19) to 2021 (16), and then exceeding pre-pandemic activity in 2022 (44).

Factors that may possibly explain the notification increases include changes in national testing policies; maintenance of water systems used in buildings vacant during the pandemic and changing weather patterns. The increase in Legionnaires’ disease cases identified in Scotland is also reflected across Europe.

Legionella bacteria can be found in water sources, in both natural and man-made environments such as air-conditioning units, jacuzzies and showers.

Hazel Henderson, Consultant at Public Health Scotland, said:

“Legionella bacteria exposure most often occurs when a person breathes in tiny water droplets containing the bacteria. When travelling, running any showers and taps on hot for a few minutes and opening windows where possible, can help minimise any risk of infection. Only a minority of people go on to develop symptoms, however, those who smoke or have underlying medical conditions are at higher risk.

“A less common type of legionella bacteria can be found in damp potting compost or mud. It is advisable to ensure good hygiene in relation to gardening by wearing gloves, potting plants outdoors, and   a mask if the workspace is dusty, particularly if indoors. It’s important to wash hands immediately afterwards, especially before eating or drinking.”

View the ‘Legionnaires’ disease in Scotland surveillance report for 2017 to 2022’