5-84
Assessment: This is a clinical diagnosis.
Differential Diagnosis
Typhoid fever - usually rose spots are few and short -lived, elevated WBC
Malaria - no rash; parasites seen on blood smears
Leptospirosis - generally have more intense conjunctival redness, may see jaundice, rash is more petechial
if present
Meningococcemia - petechial rash may progress to purpura, meningitis symptoms are common, rapid
progression
Dengue - prominent myalgias and fever (breakbone fever)
Others - syphilis (usually no fever), drug reaction or side effect, rubeola or rubella (different rash; see topics).
Plan:
Rocky Mountain Spotted Fever (and Boutonneuse fever): Treat early based on clinical considerations.
Treatment: Doxycycline 100mg bid x 7 days (or at least 48 hours afebrile), or chloramphenicol 500
mg po qid x 7 days
Zoonotic Disease Considerations for RMSF
Principal Animal Hosts: Rabbits, field mice, dogs
Clinical Disease in Animals: Fever, anorexia, lymphadenopathy, polyarthritis, coughing, dyspnea, abdominal
pain, edema of face or extremities
Probable Mode of Transmission: Bite of infected ticks, or crushing Dermacentor variabilis or andersoni
ticks on skin
Known Distribution: Western Hemisphere
Zoonotic Disease Considerations for Boutonneuse Fever
Principal Animal Hosts: Dogs, rodents
Clinical Disease in Animals: Tick paralysis
Probable Mode of Transmission: Bite of infected tick
Known Distribution: Europe, Asia, Africa
Typhus
Treatment: Doxycycline 200 mg po load then 100 mg po q day for 10 days (or until 48 hours afebrile),
or Tetracycline 25 mg/kg po in divided 6-8 hour doses until 48-72 hours afebrile, or doxycycline single
dose 5mg/kg. Alternatives are ciprofloxacin and azithromycin (since resistance in Thailand is being seen to
doxycycline and tetracycline). Use IV fluids cautiously.
Zoonotic Disease Considerations for Typhus
Principal Animal Hosts: Flying squirrels
Clinical Disease in Animals: Asymptomatic
Probable Mode of Transmission: Human louse; squirrel fleas or ticks suspected
Known Distribution: Worldwide; Eastern USA in squirrels
Scrub typhus
Treatment: Doxycycline 100 mg po bid for 7 days (resistance in Thailand to tetracycline and chloram-
phenicol)
Zoonotic Disease Considerations for Scrub Typhus
Principal Animal Hosts: Rodents
Clinical Disease in Animals: Asymptomatic
Probable Mode of Transmission: Bite of infected larval trombiculid mites
Known Distribution: “Typhus islands” in Asia, Australia, and East Indies
Murine typhus
Treatment: Doxycycline 100 mg/day until 2-3 days after defervescence