Rocky mountain spotted fever: Difference between revisions
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**Begins as a blanching maculopapular rash that evolves to become a petechial rash | **Begins as a blanching maculopapular rash that evolves to become a petechial rash | ||
**Usually 2-5 days after fever subsides | **Usually 2-5 days after fever subsides | ||
**Starts on extremities and spreads inward | **Starts on extremities and spreads inward (centripetally) | ||
**Can involve palms and soles | **Can involve palms and soles | ||
===Complications=== | ===Complications=== | ||
*Secondary to host response against infected endothelial cells | *Secondary to host response against infected endothelial cells | ||
Revision as of 15:07, 4 January 2015
Background
- Most frequent rickettsial disease reported in the US.
- Caused by Rickettsia rickettsii
- Obligate intracellular, gram negative bacteria
- Predilection for vascular endothelial cells
- Spread by ticks
- American Dog Tick (Dermacentor variabilis) Most common vector
- Rocky Mountain Wood Tick (Dermacentor andersoni)
- Brown Dog Tick (Rhipicephalus sanquineus)
- Cayenne Tick (Amblyomma cajennense)
- Seasonal distribution with most infections occurring in the summer months
- Widely distributed in the US
- States with the highest incidence are Oklahoma, Nebraska, Arkansas, Tennessee and North Carolina
- Overall incidence is increasing while mortality is falling
Clinical Features
- Symptoms generally begin 2-14 days after inoculation from an infected tick
Early symptoms
- Non specific and highly variable
- Fever
- Nausea/Vomiting
- Abdominal pain
- Myalgias
- Headache
- Fatigue
- Conjunctivitis
Late symptoms
- Arthralgias
- Rash
- Begins as a blanching maculopapular rash that evolves to become a petechial rash
- Usually 2-5 days after fever subsides
- Starts on extremities and spreads inward (centripetally)
- Can involve palms and soles
Complications
- Secondary to host response against infected endothelial cells
- Vasculitis
- Myocarditis
- Interstitial pneumonitis
- Encephalitis
Diagnosis
- Immunofluorescence
- PCR
- Titers
Work-Up
- EKG (Myocarditis)
- Chem 7 (Hyponatremia)
- CBC (Thrombocytopenia)
Differential Diagnosis
- Other Tick Borne Illnesses
- Non-specific viral illness
Lower Respiratory Zoonotic Infections
- Psittacosis
- Anthrax (Bacillus anthracis)
- Brucellosis (Brucella species)
- Q fever (C. burnetti)
- Pasteurellosis (Pasteurella multocida)
- Melioidosis (Burkholderia pseudomallei)
- Rocky Mountain Spotted Fever (R. rickettsii)
- Pulmonic Plague (Yersinia pestis)
- Influenza A
- Hantavirus
Tick Borne Illnesses
- Babesiosis
- Colorado tick fever
- Ehrlichiosis
- Heartland virus
- Lyme
- Murine typhus
- Rocky mountain spotted fever
- Southern tick-associated rash illness (STARI)
- Tick paralysis
- Tularemia
Treatment
- Doxycycline 100mg BID for 5-7 days
- Children - 2.2mg/kg BID
- Chloramphenicol 50-100 mg/kg/day div Q6hr (Max dose = 4g/day)