Which is a characteristic of a person-to-person propagated epidemic?

• A. There are more cases of the disease than expected
• B. The disease must necessarily be transmitted through a vector
• C. The spread of the disease can be attributed to a common vehicle
• D. There is gradual build up of cases before we epidemic becomes easily noticeable

Answer: (D)

A person-to-person propagated epidemic spreads through direct contact, so transmission occurs in generations. Each infected person can pass the disease to others, who then pass it to yet more people, creating a slow, wave-like spread. Because new cases arise from successive generations, the total number of cases rises gradually and the outbreak becomes noticeable only after several transmission cycles. This gradual buildup is the hallmark of propagated epidemics, distinguishing them from outbreaks that spike quickly from a single source or a vector-driven transmission.

The other patterns describe different scenarios: a general surge in cases can occur in many outbreaks, not specifically due to person-to-person spread; vector transmission involves a disease carried by an intermediary organism; and a common vehicle indicates a single exposure source leading to a rapid rise.