Patient came from Nagaland and shows positive test with OXK antigen. Diagnosis is-

Ans. is 'b' i.e., Scrub typhus Weil felix reactiono This reaction is an agglutination test in which sera are tested for agglutinins to O antigens of certain nonmotile proteus strains OX - 19, OX - 2 and OX - K.o The basis of the test is the sharing of an alkali - stable carbohydrate antigen by some rickettsiae and by certain strains of proteus, P vulgaris OX - 19 and OX - 2 and P mirabilis OX - K.o The test is usually done as a tube agglutination, though rapid slide agglutination methods have been employed for screening.Weil feiix ReactionDiseaseOX-19OX-2OX-KRocky Mountain spotted fever++-Rickettsia] pox---Epidemic typhus+--Bril - Zinsser disease+/---Scrub typhus--+Endemic typhus+--Trench fever---Q fever---