Understanding the True Prevalence of Legionella Bacteria and Common Myths Debunked

Legionella bacteria are often misunderstood, with many believing they are only found in air conditioning systems and water towers. However, recent research by Griffith University reveals that exposure sources are more diverse and include soil. Associate Professor Lara Herrero from Griffith's Institute for Biomedicine and Glycomics conducted a study analyzing blood samples from Queensland donors to assess exposure levels to Legionella bacteria, which can cause Legionnaire's disease, a serious form of pneumonia. The study compared samples collected in 2016 and 2023, covering periods before and after a noted increase in disease incidence. Findings indicated that while overall Legionella prevalence remained stable, the specific species L. pneumophila, commonly associated with air conditioning units, decreased, whereas L. longbeachae, typically found in soil, increased. This aligns with public health data showing that L. longbeachae-related cases have dominated in recent years. Since this species is prevalent in soil, especially potting soil, individuals engaged in gardening should be cautious—wearing masks can significantly reduce exposure risk. Vulnerable groups, including the elderly and immunocompromised, should exercise extra care. Legionnaire's disease, which is infectious through inhalation and not person-to-person, presents symptoms such as fever, chills, cough, and breathing difficulties. Though relatively rare, it can be life-threatening, accounting for up to 15% of community-acquired pneumonia cases. The research emphasizes the importance of understanding diverse exposure routes to better prevent and manage Legionella infections.

Source: https://medicalxpress.com/news/2025-09-de-mystifying-common-misconception-prevalence.html