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
Which one of the following ricketsial diseases is transmitted by louse - 
Select and explain. 
A. Epidemic typhus, B. Rockery mountain spotted fever, C. Q-fever, D. Endemic typhus
A: Epidemic typhus
Answer: A: Epidemic typhus 
Explanation: Epidemic typhus has louse as vector. REF. PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICAL 21ST EDITION. PAGE NO - 274