Airborne Precautions

Excerpt

An airborne disorder is any disease that is caused by a microorganism that is transmitted through the air. Various pathogens, including bacteria, viruses, and fungi, cause many clinically important airborne diseases. These organisms may be transmitted through sneezing, coughing, spraying of liquids, spreading dust, talking, or any activity that generates aerosolized particles. It is important to know that airborne diseases generally do not include disorders caused by air pollution, poisons, smog, and dust. According to the World Health Organization, “Airborne transmission of infectious agents refers to the transmission of disease caused by the dissemination of droplet nuclei that remain infectious when suspended in air over long distance and time.” Airborne transmission can be obligate or preferential depending on whether it is transmitted via droplet nuclei or has multiple other transmission routes.

The microorganisms transmitted by an airborne route may be spread via fine mist, dust, aerosols, or liquids. The aerosolized particles are generated from a source of infection, such as an infected patient or animal. In addition, aerosols may be generated from biological waste products that accumulate in garbage cans, caves, and dry arid containers. In aerosolization, microorganisms that are less than 100 micrometers in size float in the air. These microorganisms, contained in droplets, are then dispersed via air currents to varying distances and can be inhaled by susceptible hosts. Although most particles drop off within the vicinity, the infected aerosolized particles often remain suspended in the air and may even travel considerable distances. The transmission rate decreases as the distance between the source and susceptible individuals increases. Airborne transmission necessitates using available interventions in healthcare facilities to break the transmission of airborne particles from patient to patient and patient to healthcare workers. Airborne particles are considered highly infectious as they often remain suspended in the air and travel by air currents to different parts of the hospital, where there is a potential of them being inhaled by others. In some cases where there is inadequate ventilation, the airborne particle may remain in the hospital room for extended periods and may even be inhaled by a newly admitted patient. The control and prevention of airborne transmission of infections are not simple; they require airflow control with specially designed ventilation systems, antiseptic techniques, wearing personalized protective equipment (PPE), and performing basic infection prevention measures like hand washing.

Airborne Organisms

In almost all cases, airborne pathogens cause an inflammatory reaction of the upper airways, affecting the nose, sinuses, throat, and lungs. The involvement of these structures may result in sinus congestion, sore throat, and lower respiratory tract symptoms. Any coughing or sneezing activity may generate aerosolized particles, leading to airborne transmission. Some of the common pathogens that may spread via airborne transmission are:

1. Anthrax

2. Aspergillosis

3. Blastomycosis

4. Chickenpox

5. Adenovirus

6. Enteroviruses

7. Rotavirus

8. Influenza

9. Rhinovirus

10. Neisseria meningitidis

11. Streptococcus pneumoniae

12. Legionellosis

13. Measles

14. Mumps

15. Smallpox

16. Cryptococcosis

17. Tuberculosis

18. Bordetella pertussis

19. Severe acute respiratory syndrome (SARS)

20. Middle East respiratory syndrome

21. Coronavirus disease 2019 (COVID-19)

This non-exhaustive list only encompasses some of the common diseases implicated in airborne transmission. A special note to be made is regarding COVID-19, the 21st-century pandemic which is thought to spread through airborne routes (among other routes). Active measures to prevent airborne transmission have been shown to curb its spread. Airborne diseases are not exclusive to humans and can also infect animals. A notable example is poultry, often affected by an avian disorder (Newcastle disease), which is also transmitted via an airborne route. However, it is important to understand that exposure to an animal or a patient with an airborne disease does not automatically ensure disease transmission. The infection also depends on the host's immunity, the amount of exposure, and the duration of exposure to the infected patient.

Airborne Particles Generated from Medical Equipment

Besides patients, several medical and surgical procedures may also generate aerosolized infectious particles. These airborne particles are usually generated by manipulating the lung airways. These include:

1. Manual ventilation with a bag and mask

2. Intubation

3. Open endotracheal suctioning

4. Bronchoscopy

5. Cardiopulmonary resuscitation

6. Sputum induction

7. Chest physiotherapy

8. Lung surgery

9. Nebulizer therapy and steam inhalation

10. Non-invasive positive pressure ventilation (BIPAP, CPAP)

11. An autopsy of the lungs

Care must be taken while performing the above medical procedures on patients known to have diseases with high transmissibility through airborne routes.