In the Weil-Felix reaction, agglutination with Proteus vulgaris OX-2 strain is classically seen in infection with:

• A Rickettsia conorii ✓
• B Orientia tsutsugamushi
• C Rickettsia prowazekii
• D Rickettsia akari

Explanation

Weil-Felix exploits cross-reactive antigens shared between rickettsiae and certain Proteus strains. OX-19 reacts in epidemic and endemic typhus and spotted fever group infections, OX-2 reacts mainly in spotted fever group including Rickettsia conorii (Indian tick typhus), and OX-K reacts in scrub typhus caused by Orientia tsutsugamushi. Scrub typhus is the key distractor because OX-K, not OX-2, is its marker.

Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.