An army jawan posted in a remote forest area had fever and headache. His fever was 104degF and pulse was 70 per min. He had an erythematous lesion of about 1 cm on the leg surrounded by small vesicles, along with generalized lymphadenopathy at the time of presentation to the referral hospital. His blood sample was collected to perform serology for the diagnosis of Rickettsial disease. Which one of the following results in Weil felix reaction will be diagnostic in this clinical setting?

The history and clinical features described are suggestive of scrub typhus. OX-K is specific for scrub typhus. Scrub typhus is transmitted by trombiculid mites which are found in areas of heavy scrub vegetation. The bite of this mite leaves a characteristic black eschar that is useful to the doctor for making the diagnosis. DIAGNOSIS: The cheapest and most easily available serological test is the Weil-Felix test, but this is notoriously unreliable. The gold standard is indirect immunofluorescence