Airborne pathogens are microorganisms that can be transmitted through the air by small particles, droplets or dust and cause disease when inhaled or deposited on mucous membranes. They include viruses, bacteria and fungal spores that remain viable while suspended and can infect hosts over varying distances.
Explanation
Transmission of airborne pathogens occurs when an infected person or environmental source generates respiratory droplets or aerosols that contain infectious particles. Droplets larger than about 5 micrometres fall quickly and typically travel only short distances, whereas smaller aerosols can remain suspended and travel farther, creating opportunities for inhalation by others. Environmental factors such as humidity, temperature, ventilation and ultraviolet light affect the stability of airborne microbes and their potential to cause infection. Airborne viruses include measles virus, varicella‑zoster virus, influenza viruses, rhinoviruses and coronaviruses such as SARS‑CoV and SARS‑CoV‑2. Bacterial examples include Mycobacterium tuberculosis, which causes tuberculosis via fine droplet nuclei, and Legionella pneumophila, which grows in water systems and becomes aerosolized in cooling towers or showers. Other respiratory pathogens transmitted through the air are Streptococcus pneumoniae, Bordetella pertussis and Corynebacterium diphtheriae. Fungal spores from species like Histoplasma capsulatum, Coccidioides immitis and Aspergillus fumigatus can be dispersed by wind or construction activities and inhaled, causing pulmonary or systemic mycoses, particularly in immunocompromised individuals. Understanding airborne transmission is essential for infection control measures, including isolation rooms with negative pressure, use of respirators or masks, improved ventilation and air filtration, and vaccination where available. Host factors such as immune status and vaccination history influence susceptibility to airborne diseases, and super‑spreading events can occur when conditions favour accumulation and dissemination of aerosols.
Examples and control strategies
Measles is one of the most contagious airborne diseases; a single case can infect more than a dozen susceptible individuals in enclosed spaces. Tuberculosis continues to be a global health challenge due to airborne spread in overcrowded settings, necessitating long courses of therapy and public health monitoring. Outbreaks of Legionnaires’ disease have been traced to hotel cooling towers and building water systems that disseminate aerosols containing Legionella. During the COVID‑19 pandemic, recognition of SARS‑CoV‑2 aerosol transmission led to widespread adoption of face masks, indoor ventilation improvements and air filtration to reduce transmission. Fungal spores in dust from construction sites have caused clusters of invasive aspergillosis in hospitals, highlighting the need for environmental controls. Effective management of airborne pathogens relies on a combination of vaccination, respiratory hygiene, personal protective equipment and engineering controls to reduce exposure.
Airborne pathogens underscore the importance of respiratory infection control and environmental management. By understanding how these microbes spread through the air, public health systems can implement strategies to prevent outbreaks and protect vulnerable populations.
Related Terms: Droplet transmission, Aerosol, Respiratory infection, Infection control, Mask