Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Ehrlichia is a genus of obligate intracellular bacteria that are transmitted by ticks and can cause the disease ehrlichiosis in humans and animals. These bacteria primarily infect white blood cells, leading to various clinical symptoms.
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Ehrlichia belongs to the Alphaproteobacteria class within the Proteobacteria phylum.
These bacteria are typically transmitted through tick bites, particularly from the Lone Star tick (Amblyomma americanum) in the United States.
Ehrlichiosis, caused by Ehrlichia species, often presents with flu-like symptoms such as fever, headache, muscle aches, and sometimes rash.
Commonly studied species include Ehrlichia chaffeensis and Ehrlichia ewingii.
Diagnosis of ehrlichiosis is often confirmed through serological tests or PCR (polymerase chain reaction) assays.