Bubonic plague — DTM&H MCQ

Correct answer: A — Bubo aspirate or blood culture with urgent reference laboratory testing

The correct answer is A, bubo aspirate or blood culture with urgent reference laboratory testing. In a child with a painful inguinal bubo, fever, and an antecedent rodent die-off in a plague-endemic area of Madagascar, bubonic plague is the leading diagnosis, and confirmation requires demonstrating Yersinia pestis by microscopy and culture of an appropriate specimen. UK guidance for suspected imported plague states that detection of Y. pestis by microscopy and culture in local laboratories, supported by reference laboratory testing, is the principal diagnostic method, with bubo aspirate obtained by careful needle aspiration and blood cultures as the key specimens. Because Y. pestis is a hazard group 3 pathogen requiring enhanced biosafety precautions and statutory notification, any suspected sample must be flagged and processed with urgent reference laboratory and public health involvement, mirroring the Imported Fever Service pathway used in England. This directly addresses the epidemiological clue (rat die-off, cluster of febrile contacts) and the clinical sign (bubo) that point specifically to plague rather than another febrile illness. Why the other options are wrong: E. Tuberculin skin test: This investigates latent or active tuberculosis exposure and has no role in an acute febrile illness with a tender bubo following a rodent die-off. D. Stool culture for Vibrio cholerae: Cholera causes profuse watery diarrhoea, not fever with a painful lymphadenitic bubo, so this specimen and organism are clinically irrelevant here. C. Thick blood film for malaria alone: While malaria must always be excluded in a febrile child in an endemic area, testing for it alone ignores the bubo and rodent die-off, which are the discriminating features pointing to plague, and could delay life-saving antibiotic treatment and notification. B. Urine microscopy for terminal-spined ova: This detects Schistosoma haematobium, a chronic parasitic infection causing haematuria, not an acute feverish illness with lymphadenopathy. Key point: A febrile illness with a painful bubo after a rodent die-off in an endemic area demands bubo aspirate or blood culture sent urgently to a reference laboratory for Yersinia pestis, with parallel notification and biosafety precautions.

Reference: UK Health Security Agency (formerly Public Health England), Plague: interim guidance for clinicians in England managing suspected cases, 2018 (https://assets.publishing.service.gov.uk/media/5baa55cced915d2baae4dd00/Plague_clinical_guidance.pdf)