Why are males more susceptible to Legionellosis?
Males are consistently reported to have a higher incidence of Legionnaires’ disease than females — typically 2–3 times higher. This is due to a combination of behavioural, biological, and environmental factors:
1. Higher exposure risk
- More likely to work in high-risk environments (cooling towers, construction, water systems)
- Greater exposure to aerosolised water sources
- Higher rates of smoking, which damages lung defence mechanisms
2. Pre-existing health conditions
- Increased prevalence of:
- Chronic lung disease (e.g. COPD)
- Cardiovascular disease
- Alcohol-related illness
These reduce the body’s ability to fight infection.
3. Biological / immune differences
- Hormonal effects:
- Oestrogen may enhance immune response
- Testosterone may suppress aspects of immunity
- Females generally mount a stronger immune response, aiding bacterial clearance
4. Lung capacity (possible contributing factor)
- Males typically have larger lung volumes than females
- This may result in:
- Slightly greater inhalation of aerosolised particles during exposure
- However, this is considered a secondary factor, and evidence is limited compared to other risks
5. Health-seeking behaviour
- Men are more likely to:
- Delay seeking medical attention
- Present with more advanced disease
Bottom line
The increased risk in males is mainly driven by:
- Exposure
- Lifestyle factors (especially smoking)
- Underlying health conditions
- Immune differences
Lung capacity may play a small role, but it is not a primary driver of increased susceptibility.
