The Weil-Felix reaction is an agglutination test used for serodiagnosis of rickettsial infections, based on cross-reactivity between rickettsial antigens and somatic antigens of Proteus species. Which Proteus strain is used to diagnose scrub typhus?

• A Proteus OXK ✓
• B Proteus OX2
• C Proteus OX19
• D Proteus OX5

Explanation

Scrub typhus caused by Orientia tsutsugamushi gives agglutination with Proteus OXK. Proteus OX19 is elevated in epidemic and endemic typhus, while Proteus OX2 rises in spotted fever group infections. The pattern of agglutination with these three strains allows presumptive differentiation of rickettsial groups, although the test lacks specificity because Proteus urinary tract infection can also give positive results.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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