Ehrlichiosis
Pathogen
Ehrlichia chaffeensis, E. ewingii
Carried by
Lone star tick (Amblyomma americanum)
Ehrlichiosis is a bacterial infection carried mainly by the lone star tick. It infects white blood cells and can range from mild to serious, with a symptom picture that overlaps heavily with Anaplasmosis. In children, a rash is more common than in adults.
Symptoms
- Fever, headache, muscle aches
- Malaise and fatigue
- Rash (more common in children)
- Low white blood cell and platelet counts, elevated liver enzymes
Testing
PCR in the acute phase, paired antibody testing, and blood smear (bacteria form clusters called morulae inside monocytes).
Labs often used in the Lyme community:
See our Testing Guide to understand your options.
Geography
Most common in south-central and southeastern states, with expanding range into the Mid-Atlantic as the lone star tick spreads north.
Explore the Where Ticks Live map to see what's carried in your region.
Treatment overview
Doxycycline is first-line for all ages and is most effective started early.
Frequently asked questions
Which tick carries Ehrlichiosis?
Primarily the lone star tick (Amblyomma americanum), which is aggressive and widespread across the Southeast and increasingly the eastern US. A related Upper-Midwest form is carried by the blacklegged tick.