Scrub typhus persists in nature because Orientia tsutsugamushi is maintained vertically within its arthropod host. Which stage of the vector transmits the infection to humans?
- A Larval mite (chigger) ✓
- B Adult trombiculid mite
- C Nymphal tick
- D Adult flea
Correct answer: A. Larval mite (chigger)
Explanation
Orientia tsutsugamushi is transmitted by the six-legged larval stage (chigger) of trombiculid mites, chiefly Leptotrombidium deliense in India. Only the larva feeds on humans; the nymph and adult feed on plant juices and never bite vertebrates. The organism passes transovarially through mite generations, so the mite is the true reservoir and rodents merely amplify it. Ticks transmit spotted fever rickettsioses, fleas transmit murine typhus.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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