A 28-year-old paddy field worker in Tamil Nadu presents with fever, eschar on the leg, maculopapular rash, and lymphadenopathy. Weil-Felix reaction: OXK positive, OX2 and OX19 negative. The most likely organism is:
- A Rickettsia rickettsii
- B Orientia tsutsugamushi (scrub typhus) ✓
- C Rickettsia prowazekii
- D Rickettsia conorii
Correct answer: B. Orientia tsutsugamushi (scrub typhus)
Explanation
Scrub typhus (Orientia tsutsugamushi) is transmitted by Leptotrombidium mites; it produces a characteristic eschar at the bite site, regional lymphadenopathy, fever, and rash. Weil-Felix OXK agglutination is positive in scrub typhus; OX2 and OX19 are negative. R. prowazekii (epidemic louse-borne typhus) gives OX19 positivity. R. rickettsii and R. conorii give OX2 and OX19 positivity. Treatment is doxycycline.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.