Tick-borne relapsing fever — DTM&H MCQ

Correct answer: C — Jarisch-Herxheimer reaction after treatment of relapsing fever

The correct answer is C, Jarisch-Herxheimer reaction after treatment of relapsing fever. Louse-borne and tick-borne relapsing fever (Borrelia species) classically present with cyclical high fevers every few days and a dense spirochaetaemia visible on a thick or thin blood film, exactly as described. Doxycycline is the treatment of choice, but rapid bacteriolysis releases large amounts of spirochaetal lipoprotein, triggering a cytokine surge (TNF-alpha, IL-6, IL-8) that produces the classic Jarisch-Herxheimer picture of rigors, high fever and hypotension within hours of the first dose. This reaction is well recognised in relapsing fever, where the spirochaete load and therefore cytokine release is particularly heavy, and management is supportive (fluids, monitoring, sometimes vasopressor support) rather than stopping the antibiotic or treating as sepsis of a different cause. Why the other options are wrong: E. Immediate doxycycline allergy: Doxycycline hypersensitivity typically causes urticaria, angioedema or anaphylaxis with bronchospasm, not a delayed fever and rigor pattern temporally linked to spirochaete clearance; there is no mention of rash, wheeze or airway compromise here. A. Progression to falciparum malaria: The blood film already explains the fever pattern as spirochaetaemia, not malaria parasites, and falciparum malaria does not classically recur every 5 days nor worsen specifically after starting doxycycline. B. Acute schistosomiasis: Katayama syndrome from schistosomiasis presents with fever, urticaria, eosinophilia and hepatosplenomegaly over days to weeks after freshwater exposure, not an acute post-antibiotic reaction in a patient with known spirochaetaemia. D. Serum sickness from antivenom: There is no antivenom administration in this stem, and serum sickness develops days after antigen exposure with rash, arthralgia and lymphadenopathy, not immediately after doxycycline in a spirochaetal illness. Key point: A brisk hypotensive, febrile rigor reaction shortly after starting doxycycline for a heavy spirochaetaemia is the Jarisch-Herxheimer reaction of relapsing fever, driven by cytokine release from rapid organism lysis, and requires supportive care, not antibiotic discontinuation.

Reference: Manson's Tropical Diseases, 24th edition, Chapter on Relapsing Fever (Borrelia spp.): Jarisch-Herxheimer reaction following antimicrobial treatment.