Xenopsylla cheopis, the Oriental rat flea, is the principal vector of plague. The 'blocked flea' phenomenon in plague transmission refers to which of the following?

• A The flea's esophagus becomes blocked by blood meal coagulation
• B Yersinia pestis multiplies in the proventriculus forming a biofilm that causes regurgitation during feeding ✓
• C The flea's midgut epithelium is destroyed, preventing blood meal digestion
• D The flea's salivary glands are blocked by bacterial emboli

Explanation

In the blocked flea phenomenon, Yersinia pestis multiplies in the proventriculus of Xenopsylla cheopis forming a biofilm that obstructs the gut. When the flea attempts to feed on a new host, it regurgitates bacteria into the wound, transmitting plague. This mechanism is described in standard microbiology and Park's textbook. Option D incorrectly attributes the blockage to salivary glands rather than the proventriculus.

Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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