Measles: Airborne Transmission
The disease described is measles, and it is transmitted primarily via the airborne route (Answer A). The clinical presentation of fever, cough, coryza (the "3 Cs"), conjunctivitis, maculopapular rash, and pathognomonic Koplik spots (whitish plaques inside the mouth) with household clustering is classic for measles 1, 2.
Why Airborne Transmission is the Answer
Measles virus spreads through airborne droplet nuclei that can remain suspended in air for extended periods and travel beyond the immediate vicinity of the infected person. This distinguishes it from simple droplet transmission 1.
Key Evidence Supporting Airborne Transmission:
Measles virus can survive in air for at least one hour after an infected person leaves a room, allowing transmission to individuals who never had direct contact with the source patient 1
In a documented pediatric office outbreak, children contracted measles despite never being in the same room as the source patient, with one child arriving an hour after the infected child had departed 1
Airflow studies demonstrated that droplet nuclei from a vigorously coughing measles patient dispersed throughout entire office suites via recirculated ventilation systems 1
Attack rates remain high even with intense exposure scenarios: unvaccinated infants had an 80% attack rate, and even properly vaccinated individuals showed substantial infection risk when exposed to high viral inocula in poorly ventilated spaces 2
Clinical Implications for This Case
The fact that three siblings developed the same illness strongly supports airborne transmission, as:
Household transmission of measles occurs readily through shared air spaces, not requiring direct face-to-face contact 1, 2
Modern homes with recirculated ventilation and tight insulation facilitate airborne spread by allowing viral particles to circulate throughout the dwelling 1
The highly contagious nature of measles (R0 of 12-18) reflects its efficient airborne transmission, making it one of the most transmissible human pathogens 3
Why Other Options Are Incorrect
Droplet transmission (Option B) is insufficient to explain measles spread because droplets typically travel only 1-2 meters and fall quickly to surfaces, which cannot account for transmission to individuals who were never in proximity to the source patient 1, 3
Fecal-oral and bloodborne routes (Options C and D) are not relevant transmission mechanisms for measles, which is a respiratory virus spread through the respiratory tract 3