This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
'Prepatent period' in lymphatic filariasis is defined as the time interval between inoculation of infective larvae and - 
Select and explain. 
A. Blockage of lymphatics, B. First appearance of detectable microfilaria, C. Development oflymphoedema, D. Development of adult worm
B: First appearance of detectable microfilaria
Answer: B: First appearance of detectable microfilaria 
Explanation: Ans. is 'b' i.e., First appearance of detectable microfilaria o The time interval between inoculation of infective larvae and first appearance of detectable microfilaria is known as "prepatent period". o The time interval from invasion of infective larvae to the development of clinical manifestations is known as the "clinical incubation period" --> It is commonly 8-16 months.