Question:medium

A propagated (progressive) epidemic showing multiple peaks separated by the incubation period is characteristically seen in which of the following diseases?

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Peaks one incubation period apart = serial person-to-person spread — think a contagious virus.
Updated On: Jun 25, 2026
  • Measles
  • Staphylococcal food poisoning
  • Typhoid fever (common-source)
  • Salmonella food poisoning (salmonellosis)
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The Correct Option is A

Solution and Explanation

The shape of the epidemic curve tells the story. A propagated epidemic is fuelled by one infected person passing the agent to the next, so cases arrive in successive waves; each wave sits about one incubation period after the previous one, giving a curve with several rising peaks rather than a single spike.

For that pattern to appear, the disease must spread directly between people. Measles fits exactly — an extremely transmissible droplet-spread virus that moves from case to case and generates the classic multi-peaked propagated curve.

The food-poisoning options behave differently. Staphylococcal and Salmonella food poisoning are point-source events: many people eat the same contaminated meal and fall ill together, producing one tight peak with no serial generations. Typhoid is likewise usually a water- or food-borne common-source outbreak, not the prototypical propagated epidemic.

$\text{Peaks} \approx 1 \text{ incubation period apart} \Rightarrow \text{person-to-person spread}$

\[\boxed{\text{Measles}}\]
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