Question
Identify the graph below:
| A. |
Common-source epidemic due to a single (point-source) exposure
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| B. |
Common-source epidemic due to continuous exposure
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| C. |
Common-source epidemic due to intermittent exposure
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| D. |
Propagated epidemic due to person-to-person transmission
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Show Answer
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Correct Answer » C
Explanation
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The graph is an epidemic curve:
- X-axis: Date of onset of illness
- Y-axis: Number of cases
- It shows multiple irregular peaks, separated by periods with fewer cases.
This pattern is characteristic of an intermittent common-source epidemic, in which exposure to the same source occurs repeatedly but irregularly.
Why not the others:
- A. Point-source epidemic: Usually shows a single sharp peak following one-time exposure.
- B. Continuous exposure epidemic: Shows a prolonged plateau or sustained occurrence of cases due to continuous exposure.
- D. Propagated epidemic: Shows successive waves, usually separated by approximately one incubation period, due to person-to-person transmission.
