Question:easy
The number of susceptible persons who develop the disease within the range of the incubation period after contact with a primary case is the:
The number of susceptible persons who develop the disease within the range of the incubation period after contact with a primary case is the:
Show Hint
New cases among contacts of the index case within one incubation period.
Updated On: Jun 23, 2026
- Secondary attack rate
- Case fatality rate
- Primary attack rate
- Tertiary attack rate
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: Identify the key phrases - contacts of a primary case, becoming ill within the incubation period. Disease spreading from an index case to susceptible contacts defines the secondary attack rate. Step 2: Its formula divides the number of contacts who fall ill within one incubation period by all susceptible contacts exposed, multiplied by 100: $SAR = \dfrac{\text{contacts who become cases}}{\text{susceptible contacts}} \times 100$. Step 3: Clinically SAR quantifies how readily an organism spreads among close contacts, so a high SAR signals high communicability. Step 4: Eliminating alternatives, case fatality rate is about deaths, primary attack rate is about first-generation cases in the community, and tertiary attack rate is not a recognised index, leaving the secondary attack rate as correct. \[\boxed{\text{Secondary attack rate}}\]
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