Ehrlichiosis ewingii infection

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Human ewingii ehrlichiosis
Classification and external resources
ICD-9-CM 082.4
eMedicine med/3391 ped/655 emerg/159

Ehrlichiosis ewingii infection[1] is an infectious disease caused by an intracellular bacteria, Ehrlichia ewingii.[2] The infection is transmitted to humans by the tick, Amblyomma americanum. This tick can also transmit Ehrlichia chaffeensis, the bacteria that causes human monocytic ehrlichiosis (HME).

Symptoms[edit]

Patients can present with fever, headache, myalgias, and malaise. Laboratory tests may reveal thrombocytopenia, leukopenia, and evidence of liver damage.

Mechanism[edit]

Humans contract the disease after a bite by an infected tick of the species Amblyomma americanum.[citation needed] Those with an underlying immunodeficiency (such as HIV) appear to be at greater risk of contracting the disease. Compared to HME, ewingii ehrlichiosis has a decreased incidence of complications.[3]

Like Anaplasma phagocytophilum, the causative agent of human granulocytic ehrlichiosis, Ehrlichia ewingii infects neutrophils. Infection with E. ewingii may delay neutrophil apoptosis.[4]

Diagnosis[edit]

In endemic areas, a high index of suspicion is warranted, especially with a known exposure to ticks. The diagnosis can be confirmed by using PCR.[5] A peripheral blood smear can also be examined for intracytoplasmic inclusions called morulae.

Treatment[edit]

The treatment of choice is doxycycline.

See also[edit]

References[edit]

  1. ^ Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1130. ISBN 1-4160-2999-0. 
  2. ^ Patnaik MM (June 2009). "Inclusion bodies in tick-borne diseases diagnosed in patients from northern Wisconsin". Clin Med Res. 7 (1-2): 45–7. doi:10.3121/cmr.2009.807.818. PMC 2705270Freely accessible. PMID 19574488. 
  3. ^ Paddock CD, Folk SM, Shore GM, et al. (November 2001). "Infections with Ehrlichia chaffeensis and Ehrlichia ewingii in persons coinfected with human immunodeficiency virus". Clinical Infectious Diseases. 33 (9): 1586–94. doi:10.1086/323981. PMID 11568857. 
  4. ^ Xiong Q, Bao W, Ge Y, Rikihisa Y (April 2008). "Ehrlichia ewingii infection delays spontaneous neutrophil apoptosis through stabilization of mitochondria". The Journal of Infectious Diseases. 197 (8): 1110–8. doi:10.1086/533457. PMID 18462160. 
  5. ^ Gusa, Aa; Buller, Rs; Storch, Ga; Huycke, Mm; MacHado, Lj; Slater, Ln; Stockham, Sl; Massung, Rf (Nov 2001). "Identification of a p28 gene in Ehrlichia ewingii: evaluation of gene for use as a target for a species-specific PCR diagnostic assay." (Free full text). Journal of clinical microbiology. 39 (11): 3871–6. doi:10.1128/JCM.39.11.3871-3876.2001. PMC 88457Freely accessible. PMID 11682500.