This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
Epidemic typhus is cause by - 
Select and explain. 
A. R.typhi, B. R.prowazeki, C. R.rickettsii, D. R.tsutsugamushi
B: R.prowazeki
Answer: B: R.prowazeki 
Explanation: Ans. is 'b' i.e., R. prowazeki DiseaseAgentInsect vectorMammalian reservoir1.Typhus group a. Epidemic typhusR. prowazekiiLouseHumans b. Murine typhus (Endemic typhus)R. typhiFleaRodents c. Scrub typhusR. tsutsugamushiMiteRodents2.Spotted fever group a. Indian tick typhusR. conoriiTickRodents, dogs b. Rocky mountain spotted feverR. rickettsiiTickRodents, dogs c. Rickettsial poxR. akariMiteMice3.Others a. Q feverC. burnetiiNilCattle, sheep, goats. b. Trench feverRocholimaca quintanaLouseHumans