Diphtheria is transmitted by which route?

• A. By skin contact
• B. By vector transmission
• C. By inhalation of respiratory secretions
• D. By fecal-oral route

Answer: (C)

This question tests how respiratory pathogens spread, specifically droplet transmission. Diphtheria is caused by Corynebacterium diphtheriae and is mainly transmitted when an infected person coughs, sneezes, or talks, releasing respiratory droplets that another person inhales or that contact mucous membranes. This mode of spread—droplets carried in close-range respiratory secretions—best explains why inhalation of respiratory secretions is the correct route. Other routes like vector transmission, fecal-oral spread, or transmission by skin contact are not the typical or most important means by which diphtheria spreads, though cutaneous diphtheria can occur in some settings.