A 60-year-old man who survived an epidemic of louse-borne typhus in his youth presents decades later with a mild febrile illness lasting about 10 days. Serology shows antibodies to Rickettsia prowazekii. What is the underlying mechanism of this illness?
- A Reinfection from a fresh louse bite
- B Reactivation of latent organisms persisting in reticuloendothelial tissue ✓
- C Cross-reactive immunity triggered by Proteus OX-19 antigen
- D Horizontal spread from a rodent reservoir through flea faeces
Correct answer: B. Reactivation of latent organisms persisting in reticuloendothelial tissue
Explanation
Brill-Zinsser disease is recrudescent epidemic typhus caused by reactivation of dormant Rickettsia prowazekii persisting for years in lymph nodes and other reticuloendothelial sites. It is milder than primary infection, the rash may be sparse or absent, and it can seed fresh epidemics if lice are present. Option A is wrong because no new exposure is required, and option D describes murine typhus caused by R. typhi.
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.