How Measles is Transmitted
Measles spreads primarily through the airborne route, with viral particles remaining suspended in air for extended periods and capable of traveling long distances to infect susceptible individuals—making it one of the most contagious infectious diseases known. 1
Primary Transmission Mechanism
Airborne transmission is the predominant mode by which measles spreads, distinguishing it fundamentally from typical droplet-transmitted infections like influenza that require close proximity (≤1 meter). 1
The virus can remain suspended in aerosol particles and infect individuals who were never in the same room as the infected person at the same time, behaving similarly to tuberculosis or varicella rather than typical respiratory droplet infections. 1
Among unimmunized individuals exposed to measles, over 90% will develop disease, reflecting the extraordinary efficiency of airborne spread. 1
Evidence from Real-World Outbreaks
A documented pediatric office outbreak demonstrated that measles virus survived in the air for at least one hour after the source patient left, with secondary cases occurring in children who arrived after the infected child had departed. 2
In this outbreak, airflow studies showed that droplet nuclei generated in one examining room dispersed throughout the entire office suite, confirming long-distance airborne transmission. 2
The source patient was coughing vigorously, and three children who contracted measles were never in the same room with the source patient. 2
Contagious Period
Infected individuals remain contagious from 4 days before rash onset through 4 days after rash onset. 3, 1
The virus is transmitted by aerosols through human-to-human contact during this highly contagious period. 4
Critical Infection Control Implications
Airborne infection isolation rooms (negative pressure) are mandatory for suspected or confirmed cases, and N95 respirators—not simple surgical masks—are required for all healthcare personnel entering patient rooms, regardless of immunity status. 1
Hand hygiene practices, while essential for many infectious agents, are of secondary importance for measles because the virus is transmitted predominantly through the air rather than by contact. 1
Modern office design with tight insulation and recirculated ventilation may predispose to airborne transmission, making proper ventilation and airborne precautions critical. 2
Common Pitfall to Avoid
Do not treat measles like a standard droplet-precaution illness (such as influenza). The virus's ability to remain airborne for extended periods and travel long distances requires full airborne precautions with negative pressure rooms and N95 respirators, not just surgical masks and standard droplet precautions. 1