The secondary attack rate (SAR) of cholera in a household is 40%. This means:
- A 40% of the entire population develops cholera after an index case
- B 40% of susceptible household contacts develop disease after exposure to the index case ✓
- C 40% of all cases in the outbreak are secondary to the index case
- D The household transmission efficiency is 40% of the community attack rate
Explanation
Secondary attack rate (SAR) is the number of new cases among susceptible contacts of a primary case within the maximum incubation period, expressed as a percentage of all susceptible contacts. SAR measures the transmissibility of the pathogen in close contact settings (e.g., household). For cholera, household SAR varies but is typically lower than for airborne diseases. SAR is not the proportion of cases in the overall outbreak, nor does it include the index case in the denominator. It is distinct from the primary attack rate (which applies to the first wave of an outbreak) and from the overall attack rate.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.