Murine typhus is a rickettsial infection caused by Rickettsia typhi, transmitted primarily by rat fleas (Xenopsylla cheopis). The disease is endemic in warm, coastal areas of the tropics and subtropics, with seasonal peaks (e.g., April–July in Texas). Key features include:

• Transmission:
  • Fleas infesting rats defecate near bite sites; infection occurs when humans scratch the bites or inhale aerosolized feces.
  • Rarely, human body lice (Pediculus humanus corporis) can transmit R. prowazekii (epidemic typhus), but not R. typhi.
• Symptoms:
  • Fever, headache, myalgia, and a macular rash (often sparing palms/soles) typically develop 6–14 days post-exposure.
  • Complications may include pneumonitis, encephalitis, or renal failure (rare).
• Diagnosis:
  • Serology (Weil-Felix reaction with OX-19 antigen) or PCR on blood/serum.
  • Clinical suspicion is critical due to nonspecific symptoms.
• Treatment:
  • First-line: Doxycycline (100 mg twice daily for 7 days) or chloramphenicol (500 mg every 6 hours for 7 days).
  • Pregnancy: Chloramphenicol is preferred; doxycycline may be used in the second/third trimester.
• Prevention:
  • Rat and flea control (insecticides, rat-proofing buildings).
  • No vaccine is available.
• Prognosis:
  • Mortality is low (~0.4%) with treatment; untreated, mortality may reach 10–30% in severe cases.