A 32-year-old farmer presents with sudden-onset fever, painful inguinal bubo and prostration. Giemsa-stained smear of aspirate from the bubo shows small Gram-negative bacilli with intensely stained ends giving a 'closed safety pin' appearance. Which vector transmits this organism?
- A Xenopsylla cheopis rat flea ✓
- B Ixodes tick
- C Phlebotomus sandfly
- D Glossina tsetse fly
Correct answer: A. Xenopsylla cheopis rat flea
Explanation
Bipolar staining with darker stained ends producing the closed safety pin appearance on Wayson or Giemsa stain is classic for Yersinia pestis, the cause of bubonic plague. Transmission occurs through the bite of the rat flea Xenopsylla cheopis, whose proventriculus becomes blocked by multiplying bacilli, forcing infective regurgitation into the bite site. Ixodes ticks transmit Borrelia burgdorferi, sandflies transmit Leishmania and bartonellosis, and tsetse flies transmit trypanosomes.
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.