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
Transovarian transmission is a feature of- 
Select and explain. 
A. Scrub fever, B. Epidemic typhus, C. Endemic typhus, D. Trench fever
A: Scrub fever
Answer: A: Scrub fever 
Explanation: The causative agent of scrub typhus: Rickettsia tsutsugamushi. It is the larva that feeds on veebrate hosts and picks up the rickettsias. The larval stage serves as both as a reservoir, through ovarian transmission and as a vector for infecting humans and rodents (refer pgno 300 park 23rd edition)