This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Which is propagative? 
Select and explain. 
A. Plague, B. Filaria, C. Malaria, D. All
A: Plague
Answer: A: Plague 
Explanation: (A) propagative:The agent merely multiplies in the vector but no change in the form e.g plague bacilli in rat fleas (B) cyclopropagative : The agent changes in number and form e.g malaria parasite in mosquito (C) cyclodevelopmental: The disease agent undergoes only developmental but no multiplication e.g microfilaria in mosquito (refer pgno:98 park 23 rd edition)