This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
Microfilaria endemicity index is - 
Select and explain. 
A. % of a persons showing MF in blood and diseased individual, B. % of persons showing MF in blood only, C. Number of MF in the blood, D. Average no. Persons with positive slides
A: % of a persons showing MF in blood and diseased individual
Answer: A: % of a persons showing MF in blood and diseased individual 
Explanation: <p> filarial indices 1. Microfilaria rate: percentage of persons showing microfilaria in their peripheral blood (20 cu. mm) in sample population, one slide being taken from each person. 2. Filarial endemicity rate: percentage of persons examined showing microfilaria in their blood/disease Manifestation / both. 3. Microfilarial density: number of microfilaria per unit volume of blood in samples from individual person. 4. Filarial disease rate. {Reference: park&;s textbook of preventive and social medicine, 23rd edition, pg no.274}</p>