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
Epidemic typhus cause and vector is 
Select and explain. 
A. R. prowazki and louse, B. R. typhi and mite, C. R. conori and tick, D. R. akari and mite
A: R. prowazki and louse
Answer: A: R. prowazki and louse 
Explanation: Epidemic Typhus Is a type of rickettsial disease of typhus group : Recrudence form of Epidemic typhus : Brill Zinsser Disease Was the 'most formidable rickettsial disease in past' Causative agent: R.prowazekii Vector : Louse (p.capitis,p.corporis) Mode of Transmission: (Not by Louse bite) Scratching and inoculation with infected louse faeces Crushing infected louse on body Inhalation of infected louse faeces or dust Clinical picture : Prolonged febrile illness, Vasculitis Drug of choice : Tetracycline Under International Health Regulations (IHRs), "Louse borne typhus is a disease under surveillance" Ref: Park 25th edition Pgno : 316