Compared with Lyme disease, Rocky Mountain spotted fever may cause which of the following complications?

• A. Causes painful joint swelling after a few days or weeks.
• B. Can cause paralysis and cardiorespiratory collapse.
• C. May be confused with rheumatoid arthritis.
• D. Presents with flu-like symptoms and a bull's-eye rash.

Answer: (B)

Rocky Mountain spotted fever can cause widespread vasculitis from the infection, which can harm the nervous system and the heart–lung system. When the nervous system is affected, weakness or paralysis can occur; when the cardiovascular and respiratory systems are involved, it can lead to shock and respiratory failure (cardiorespiratory collapse). This pattern of potentially rapid, life‑threatening complications is more typical of RMSF than Lyme disease, whose late complications are usually arthritis and certain neurologic symptoms like facial palsy, and whose rash is classically erythema migrans rather than a petechial eruption. So the description of paralysis and cardiorespiratory collapse best reflects the severe complications RMSF can cause compared with Lyme.