Difference between revisions of "Ehrlichiosis"

(Disposition)
 
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*Spread by the Lonestar tick (Amblyomma americanum)
 
*Spread by the Lonestar tick (Amblyomma americanum)
 
**Eastern seaboard from Florida to Maine and as far west as Iowa and Texas
 
**Eastern seaboard from Florida to Maine and as far west as Iowa and Texas
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**States with the highest incidence:<ref>Sexton DJ and McClain MT.  Human ehrlichiosis and anaplasmosis.  UpToDate.</ref>
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***Rhode Island (36.5 cases per million)
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***Minnesota (3.9 to 12.3 cases per million)
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***Connecticut (8.1 to 15.9 cases per million)
 
**People often unaware they are bitten with case fatality rate of approximately 1.8%<ref>CDC http://www.cdc.gov/ehrlichiosis/stats/</ref>
 
**People often unaware they are bitten with case fatality rate of approximately 1.8%<ref>CDC http://www.cdc.gov/ehrlichiosis/stats/</ref>
**More severe disease in immunocompromised patients ([[HIV]], Elderly, '''Asplenic''')
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**More severe disease in immunocompromised patients ([[HIV]], Elderly, '''[[Asplenic]]''')
  
 
[[File:Lone Star Tick.jpg|thumb|Lone Star Tick (preserved]]
 
[[File:Lone Star Tick.jpg|thumb|Lone Star Tick (preserved]]
  
 
==Clinical Features==
 
==Clinical Features==
*Fever, chills, headache, malaise, myalgias, nausea, vomiting, diarrhea, conjunctival injection
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*Variable spectrum of severity of disease
**Up to 60% of children may have a rash (30% of adults)
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*[[Fever]]/chills (abrupt onset), malaise, myalgias
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*[[Headache]]
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*[[Nausea/vomiting]], [[diarrhea]]
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*Conjunctival injection
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*[[Rash]]
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**Up to 60% in children, 30% of adults
  
 
==Differential Diagnosis==
 
==Differential Diagnosis==
 
{{Tick borne illnesses DDX}}
 
{{Tick borne illnesses DDX}}
  
==Diagnosis==
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==Evaluation==
 
*'''Peripheral blood smear'''<ref>http://www.cdc.gov/ehrlichiosis/symptoms/index.html#diagnosis</ref>
 
*'''Peripheral blood smear'''<ref>http://www.cdc.gov/ehrlichiosis/symptoms/index.html#diagnosis</ref>
 
*Obligate intracellular organism
 
*Obligate intracellular organism
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==Management==
 
==Management==
===Doxycycline===
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{{Ehrlichiosis antibiotics}}
*Adults: 100mg PO/IV BID x 14 days
 
*Children: (under 45 kg): 2.2 mg/kg body weight twice a day
 
  
 
==Disposition==
 
==Disposition==
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[[Category:ID]]
 
[[Category:ID]]
[[Category:TropMed]]
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[[Category:Tropical Medicine]]

Latest revision as of 23:54, 30 September 2019

Background

  • Bacterial infection of the family Anaplasmataceae common in mammals such as cattle, dogs, sheep, goats, and horses[1]
  • Spread by the Lonestar tick (Amblyomma americanum)
    • Eastern seaboard from Florida to Maine and as far west as Iowa and Texas
    • States with the highest incidence:[2]
      • Rhode Island (36.5 cases per million)
      • Minnesota (3.9 to 12.3 cases per million)
      • Connecticut (8.1 to 15.9 cases per million)
    • People often unaware they are bitten with case fatality rate of approximately 1.8%[3]
    • More severe disease in immunocompromised patients (HIV, Elderly, Asplenic)
Lone Star Tick (preserved

Clinical Features

Differential Diagnosis

Tick Borne Illnesses

Evaluation

  • Peripheral blood smear[4]
  • Obligate intracellular organism
    • Smear shows intracellular parasites only 20% of time
  • PCR
    • Most sensitive in first week of illness
  • Indirect Immunoflorescence Assay'
    • Gold Standard
    • Negative 85% of time in first 7 days of illness
    • Compare 2 samples drawn at different times
    • 4 fold increase in titers of second draw is positive
  • Enzyme Immunoassay
    • Qualitative tests, not quantitative
  • Leukopenia, elevated transaminases, thrombocytopenia often present

Management

antibiotics should be continued for 5 days after the last recorded fever

  • Adults: Doxycycline 100mg PO/IV BID x 14 days
  • Pediatrics: under 45 kg use Doxycycline 2.2mg/kg PO/IV twice a day
  • Pregnant: Rifampin 300mg PO every 12 hours

Disposition

  • most cases of Ehrlichiosis are treated as an outpatient

See also

References

  1. CDC. Ehrlichiosis. http://www.cdc.gov/ehrlichiosis.
  2. Sexton DJ and McClain MT. Human ehrlichiosis and anaplasmosis. UpToDate.
  3. CDC http://www.cdc.gov/ehrlichiosis/stats/
  4. http://www.cdc.gov/ehrlichiosis/symptoms/index.html#diagnosis