An army jawan posted in a remote forest area had fever of 104F and headache. On examination he had an erythematous lesion of about 1 cm on the leg surrounded by small vesicles, along with generalized lymphadenopathy. His blood sample is collected to perform serology for the diagnosis of Rickettsial disease. Which one of the following results in Weil-felix reaction will be helpful in diagnosing this condition?

Patient in the question stem is showing features of scrub typhus infection. When a Weil Felix test is done it shows high titers of OX K agglutinins. Weil Felix is an agglutination test in which sera are tested for agglutinins to the O antigens of ceain nonmotile proteus strains OX 19, OX 2 and OX K. Basis of the test is the sharing of an alkali stable carbohydrate antigen by some rickettsiae and by ceain strains of proteus, P vulgaris OX 19, and OX2 and P.mirabilis OX K. Sera from endemic and epidemic typhus agglutinate OX 19 and sometimes OX2 In tick borne spotted fever both OX 19 and OX2 are agglutinated In scrub typhus only OX K agglutinins are only found. This test is negative in rickettsial pox, trench fever and Q fever Ref: Sherris Medical Microbiology, 5th Edition, Chapter 40; Textbook of Microbiology By Ananthanarayan and Paniker, Page 418