Is driving a car a risk for Legionnaires' disease?

Area of Science:

• Environmental microbiology
• Public health
• Infectious diseases

Background:

• Legionnaires' disease (LD) is a severe form of pneumonia often acquired in the community.
• The transmission sources for sporadic Legionnaires' disease cases are frequently unclear.
• Car air-conditioning (AC) systems have not been widely investigated as potential reservoirs for LD pathogens.

Purpose of the Study:

• To investigate the presence of Legionella species in motor car air-conditioning systems.
• To explore a potential association between car AC usage and Legionella pneumophila antibodies in healthy individuals.

Main Methods:

• Swabs were collected from air-conditioning evaporator compartments of scrapped cars.
• Legionella species detection using loop-mediated isothermal amplification (LAMP).
• Antibody testing for Legionella pneumophila serogroups 1-6 in human subjects via microplate agglutination, coupled with questionnaires on car AC use.

Main Results:

• Legionella species were identified in 11 out of 22 (50%) of the sampled car AC systems.
• A significantly higher prevalence of microplate agglutination titres (≥1:32) was observed in subjects who reported using car AC systems.
• No direct causal link was proven, but findings suggest a potential association.

Conclusions:

• Car air-conditioning systems can harbor Legionella species.
• Usage of car AC systems may be associated with increased exposure to Legionella pneumophila.
• Further research is warranted to confirm car AC systems as a source of Legionnaires' disease transmission.