Rocky mountain spotted fever: Difference between revisions

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==Background==
==Background==
[[File:American dog tick.jpeg|thumb|American dog tick]]
*Most frequent rickettsial disease reported in the US.<ref name="http://www.cdc.gov/rmsf/">http://www.cdc.gov/rmsf/</ref>
*Most frequent rickettsial disease reported in the US.<ref name="http://www.cdc.gov/rmsf/">http://www.cdc.gov/rmsf/</ref>
*Caused by Rickettsia rickettsii
*Caused by Rickettsia rickettsii
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*Widely distributed in the US
*Widely distributed in the US
**States with the highest incidence are Oklahoma, Nebraska, Arkansas, Tennessee and North Carolina
**States with the highest incidence are Oklahoma, Nebraska, Arkansas, Tennessee and North Carolina
*Overall incidence is increasing while mortality is falling
*Overall incidence is increasing while mortality is falling<ref>Columbia University Irving Medical Center. Rocky Mountain Spotted Fever. https://www.columbia-lyme.org/rocky-mountain-spotted-fever.</ref>
**Prior to the era of antibiotics, ~30% mortality
**Currently mortality is 3-5%


==Clinical Features==
==Clinical Features==
[[File:Rocky Mountain Spotted Fever Rash.jpg|thumb|Rocky mountain spotted fever rash]]
[[File:Rr6502a1f21.gif|thumb|Maculopapular rash with central petechiae associated with Rocky Mountain spotted fever.]]
[[File:Rr6502a1f22.gif|thumb|Late-stage petechial purpuric rash involving the sole of the foot in a patient with Rocky Mountain spotted fever.]]
*Symptoms generally begin 2-14 days after inoculation from an infected tick<ref>http://www.mayoclinic.com/health/rocky-mountain-spotted-fever/DS00600</ref>
*Symptoms generally begin 2-14 days after inoculation from an infected tick<ref>http://www.mayoclinic.com/health/rocky-mountain-spotted-fever/DS00600</ref>


===Early symptoms===
===Early symptoms===
*'''Non specific and highly variable'''
*'''Non specific and highly variable'''
*Fever
*[[Fever]]
*Nausea/Vomiting
*[[Nausea/Vomiting]]
*Abdominal pain
*[[Abdominal pain]]
*Myalgias
*[[Myalgia]]s (severe calf pain)
*Headache
*[[Headache]]
*Fatigue
*[[Fatigue]]
*Conjunctivitis
*[[Conjunctivitis]]


===Late symptoms===
===Late symptoms===
*Arthralgias
*[[Rash]]
*Rash
**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 (centripetally)
**Starts on extremities and spreads inward (centripetally)
**Can involve palms and soles (50% of cases)
**Can involve palms and soles (50% of cases)
*[[Arthralgia]]s
*Positive Rumpel-Leede test
*Positive Rumpel-Leede test
**Development of petechiae at the site of blood pressure cuff and distally after compression
**Development of petechiae at the site of blood pressure cuff and distally after compression
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===Complications===
===Complications===
*Secondary to host response against infected endothelial cells
*Secondary to host response against infected endothelial cells
**Vasculitis
**[[Vasculitis]]
**[[Myocarditis]]
**[[Myocarditis]]
**Interstitial pneumonitis
**Interstitial [[pneumonitis]]
**[[Encephalitis]]
**[[Encephalitis]]
==Diagnosis==
*PCR (initially)
*Serial serologic examinations by indirect fluorescent antibody confirm the diagnosis
*Titers
==Work-Up==
*ECG (Myocarditis)
*Chem 7 ([[Hyponatremia]])
*CBC (Thrombocytopenia)


==Differential Diagnosis==
==Differential Diagnosis==
*Other [[Tick Borne Illnesses]]
*Other [[Tick Borne Illnesses]]
*Non-specific viral illness
*Non-specific [[viral syndrome|viral illness]]


{{Lower respiratory zoonotic infections}}
{{Lower respiratory zoonotic infections}}


{{Tick borne illnesses DDX}}
{{Tick borne illnesses DDX}}
==Evaluation==
*PCR (initially)
*Serial serologic examinations by indirect fluorescent antibody confirm the diagnosis
*Titers
===Work-Up===
*[[ECG]] ([[Myocarditis]])
*Chem 7 ([[Hyponatremia]])
*CBC ([[Thrombocytopenia]])


==Management==
==Management==
*[[Doxycycline]] 100mg BID for 5-7 days<ref>Shandera WX, Roig IL: Viral & Rickettsial Infections, in Papadakis MA, McPhee SJ (eds): Current Medical Diagnosis and Treatment, ed 52. USA, McGraw-Hill, 2013, (Ch) 32: p 1412-1413.</ref>
{{Rocky Mountain Spotted Fever antibiotics}}
**Indicated also in children at 2.2mg/kg BID
 
*[[Chloramphenicol]] 50-100 mg/kg/day div Q6hr (Max dose = 4g/day)
==Disposition==
**Preferred agent in pregnancy. May cause [[aplastic anemia]] and [[Grey baby syndrome]]<ref name="http://www.cdc.gov/rmsf/">http://www.cdc.gov/rmsf/</ref>


==See Also==
==See Also==

Latest revision as of 18:17, 30 July 2025

Background

American dog tick
  • Most frequent rickettsial disease reported in the US.[1]
  • 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[2]
    • Prior to the era of antibiotics, ~30% mortality
    • Currently mortality is 3-5%

Clinical Features

Rocky mountain spotted fever rash
Maculopapular rash with central petechiae associated with Rocky Mountain spotted fever.
Late-stage petechial purpuric rash involving the sole of the foot in a patient with Rocky Mountain spotted fever.
  • Symptoms generally begin 2-14 days after inoculation from an infected tick[3]

Early symptoms

Late symptoms

  • 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 (50% of cases)
  • Arthralgias
  • Positive Rumpel-Leede test
    • Development of petechiae at the site of blood pressure cuff and distally after compression

Complications

Differential Diagnosis

Lower Respiratory Zoonotic Infections

Tick Borne Illnesses

Evaluation

  • PCR (initially)
  • Serial serologic examinations by indirect fluorescent antibody confirm the diagnosis
  • Titers

Work-Up

Management

  • Doxycycline 100 mg BID for 5-7 days[4]
    • Indicated also in children at 2.2mg/kg BID
  • Chloramphenicol (CAM) 50-100 mg/kg/day div Q6hr (Max dose = 4g/day)
    • Preferred agent in pregnancy. May cause aplastic anemia and Grey baby syndrome, more common in near term or 3rd trimester[1]
    • Consideration should be made for doxycycline over CAM in the 3rd trimester

Disposition

See Also

References

  1. ↑ 1.0 1.1 http://www.cdc.gov/rmsf/
  2. ↑ Columbia University Irving Medical Center. Rocky Mountain Spotted Fever. https://www.columbia-lyme.org/rocky-mountain-spotted-fever.
  3. ↑ http://www.mayoclinic.com/health/rocky-mountain-spotted-fever/DS00600
  4. ↑ Shandera WX, Roig IL: Viral & Rickettsial Infections, in Papadakis MA, McPhee SJ (eds): Current Medical Diagnosis and Treatment, ed 52. USA, McGraw-Hill, 2013, (Ch) 32: p 1412-1413.
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