| Table 4-7 Select Rickettsial Infections |
| | Disease | | Organism/Vector | | Clinical Findings | | Treatment |
| | Rocky Mountain Spotted Fever (RMSF) | | R. rickettsii
Vector: tick
Dermacentor andersoni (wood tick in Western US)
Dermacentor variabilis (dog tick in Eastern US) | | Fever, headache, myalgias → purpuric or hemorrhagic macules and papules on wrists/ankles initially → spreads to trunk, hands, feet (“spotless” in 10–20% cases)
Mortality 15–25% if untreated | | Doxycycline preferred treatment (in pregnant patients may use chloramphenicol) |
| | Mediterranean Spotted Fever (Boutonneuse fever) | | R. conorii
Vector: brown dog tick
Rhipicephalus sanguineus | | Two forms
-Tache noir: indurated papule at site of tick bite → necrotic ulcer
-Exanthem: erythematous papules mainly over lower limbs | | Doxycycline or
chloramphenicol |
| | Rickettsialpox | | R. akari
Vector: mouse mite Liponyssoides sanguineus (formerly Allodermanyssus) | | Initial papule or vesicle at site of bite
→ Eschar, regional lymphadenopathy
→ Sudden-onset fever, chills, headahce, diffuse vesicular rash (self-limited) | | Doxycycline or
chloramphenicol |
| | Epidemic Typhus (Louse-borne) | | R. prowazekii
Vector: body louse Pediculosis humanus var. corporis
Reservoir: flying squirrel | | Fever, chills, headache → pale red macules on trunk → evolve to petechiael papules, spread to rest of body (spare face, palms, and soles)
Vascular inflammation of skin, CNS, heart, kidneys, and muscle | | Doxycycline or
chloramphenicol |
| | Endemic Typhus
(Flea-borne)
(Murine typhus) | | R. typhi
Vector: rat flea
Xenopsylla cheopis | | Fever, headache, myalgias with transient truncal maculopapular exanthem | | Doxycycline or
chloramphenicol |
| | Scrub Typhus
(Mite-borne typhus) | | R. tsutsugamushi
(now Orientia )
Vector: chigger mites Trombiculid (larval stage) | | Headache, chills, malaise and eschar at site of inoculation with lymphadenopathy → maculopapular rash on turnk, ± pulmonary and cardiac problems | | Doxycycline or
chloramphenicol |
| | Ehrlichiosis
(Monocytic (M)
Ehrlichiosis)
(Granulocytic (G)
Ehrlichiosis) | | E. chaffeenis (M)
E. phagocytophilia (G)
Vector: tick
Ambyloma americanum (M); Ixodes scapularis, Ixodes pacificus (G) | | Highly variable exanthem | | Tetracycline or
doxycycline |
| | Q Fever | | Coxiella burnetii | | No skin findings; limited febrile illness, severe headache, ± pneumonia, hepatitis, endocarditis | | Doxycycline |
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