In a district with a population of 50,000, the Annual Blood Examination Rate is 8%. Of 4,000 blood smears examined during the year, 120 are positive for malarial parasites. What is the Annual Parasite Incidence (API) of this district?
- A 0.24
- B 2.4 ✓
- C 24
- D 80
Correct answer: B. 2.4
Explanation
API equals the number of positively confirmed cases per thousand population examined during one year: 120 divided by 50,000 multiplied by 1,000 gives 2.4. Slide positivity rate (120/4000 = 3%) measures positivity among smears taken, not among total population, so multiplying SPR by population would be wrong. The figure 80 comes from wrongly dividing smears by population without scaling, and 24 results from a decimal error.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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