A 68-year-old man who emigrated from Ethiopia 30 years ago, where he had lived in crowded conditions during an outbreak of louse-borne fever, now presents with 4 days of low-grade fever, myalgia, and a sparse macular rash. Blood cultures are negative. Serology shows rising IgG antibodies to Rickettsia prowazekii. What is the most likely diagnosis?

• A Primary epidemic typhus
• B Recrudescent typhus (Brill-Zinsser disease) ✓
• C Murine typhus
• D Scrub typhus

Explanation

Brill-Zinsser disease is reactivation of dormant Rickettsia prowazekii years to decades after untreated primary epidemic typhus. It is milder than primary disease, often without the classic truncal rash, and occurs without fresh louse exposure. Because rickettsiae persist in lymphoid tissue, the antibody response is predominantly IgG rather than the IgM response of primary infection. Murine typhus is caused by Rickettsia typhi and is flea-borne, and scrub typhus is caused by Orientia tsutsugamushi.

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.