Which term describes the sequence of events that allows disease transmission?

• A. Chain of Infection
• B. Reservoir
• C. Infectious Disease
• D. Causative Agent

Answer: (B)

The sequence that describes how disease transmission occurs is the chain of infection. This concept maps out a linked series of factors: the infectious agent (the pathogen), a reservoir where it can live and multiply, a portal of exit from that reservoir, a means of transmission, a portal of entry into a new host, and a susceptible host who can be infected. Transmission happens only when all these links are present; disrupting any one link breaks the chain and prevents spread. Saying that the reservoir alone is responsible misses the bigger picture—the reservoir is just one part of the entire sequence. The other terms describe either the disease, the pathogen, or the disease-causing agent, rather than the full process that makes transmission possible. So the correct concept is the chain of infection.