Which of the following features distinguishes Coxiella burnetii from the other rickettsial organisms?
- A It is transmitted to humans primarily by the bite of an arthropod vector
- B It characteristically produces a maculopapular rash involving palms and soles
- C It typically does not produce a rash and is acquired by inhalation of infectious aerosols ✓
- D It replicates freely in the cytoplasm rather than within host cells
Correct answer: C. It typically does not produce a rash and is acquired by inhalation of infectious aerosols
Explanation
Coxiella burnetii, the agent of Q fever, is atypical among rickettsiae: humans acquire it mainly by inhaling aerosols contaminated with placental material from cattle, sheep or goats, and it does not cause a rash because vascular endothelium is not its principal target. It is an obligate intracellular organism that survives within the phagolysosome and forms a resistant spore-like small cell variant. Tick transmission occurs in nature but is not the usual route to humans.
Reference: Jawetz, Melnick & Adelberg's Medical Microbiology, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.