Most serious form of Rickettsial disease -: (A) Scrub typhus, (B) Q-fever, (C) Trench fever, (D) Rocky mountain spotted fever
Answer is D. Ans. is 'd' i.e.,Rocky mountain spotted fever "Among the Rickettsial diseases, Rocky mountain spotted fever is the most common and the most serious"The microbial chalonge "R rickettsii (causative agent of RMSF) is the most virulent Rickettsia" -- Clinical microbiology