Ehrlichia ewingii - Microscopic exam; Molecular diagnosis (PCR).


Ehrlichia ewingii is a Gram - negative bacterium Ehrlichia genus, family Anaplasmataceae with a wide geographical distribution, although the Central, South and Southeast US are geographical regions with greater presence. Ehrlichia ewingii primarily affects dogs, but can also infect people. Ehrlichia ewingii cause canine granulocytic ehrlichiosis and human granulocytic ehrlichiosis (also called human granulocytic anaplasmosis -AGH-).

The life cycle of this microorganism involves intermediate host where mature, arthropod vectors usually infected ticks (Amblyomma americanum specifically and Rhipicephalus sanguineus), which transmit the infection during feeding. Direct transmission from a common host to an unusual host is considered rare, but can be transmitted through the use of needles or surgical material vaccinations. The organism colonizes the membrane surrounding the cytoplasmic vacuoles infected mammalian host eukaryotic leukocytes. Inside the vacuoles cytoplasmic, and divided resides within them, forming intracellular pools (morulae).

In infected animals Ehrlichia ewingii, associated clinical signs appear between 7 and 14 days after infection and include fever, lethargy, difficulty walking, poliartropía and neurological manifestations such as ataxia, paresis, proprioceptive deficits and vestibular dysfunction.

In people, ewingii Ehrlichia infection causes fever, chills, headache, muscle aches, nausea and thrombocytopenia. In addition, there may be diarrhea, petechial rash, maculopapular rash and malaise. Those immunosuppressed individuals, such as people infected with HIV / AIDS are at increased risk of contracting the disease.


Recommended tests for diagnosis:


The diagnosis is based on microscopic identification of clusters of intracellular bacteria (morulae) within the cytoplasm of neutrophils can be observed in blood smears; in detecting antibodies (ELISA) or by detecting its DNA molecular diagnostic methods (PCR).

Serologic tests, and take time to have desaarrollado antibodies to identify the genus Ehrlichia to cause infection but not the species, so the molecular diagnosis as the most sensitive method for identification of Ehrlichia is recommended ewingii .

Tests in IVAMI:


  • Microscopic examination for bacteria grouped observation intracellular (morulae) in neutrophils.
  • Molecular diagnosis (PCR), to detect DNA of Ehrlichia ewingii.

Recommended sample:


  • EDTA whole blood collected (1 to 2 mL).

Preservation and shipment of sample:


  • Refrigerated (preferred) for less than 2 days (essential for microscopic examination).
  • Frozen: over 2 days (for molecular diagnostic tests only).


Delivery term:


  • Microscopic examination: 24 hours.
  • Molecular diagnosis (PCR): 24 to 48 hours.

Cost of the test: