Ehrlichiosis ewingii infection

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).

Human ewingii ehrlichiosis
SpecialtyInfectious disease

Symptoms and signs

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

Mechanism

Humans contract the disease after a bite by an infected tick of the species Amblyomma americanum. 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

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

The treatment of choice is doxycycline.

See also

References
  1. Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1130. ISBN 978-1-4160-2999-1.
  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 2705270. 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". Journal of Clinical Microbiology. 39 (11): 3871–6. doi:10.1128/JCM.39.11.3871-3876.2001. PMC 88457. PMID 11682500.
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