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Tick Diseases: Ehrlichiosis and Anaplasmosis

Per the CDC website:

Ehrlichiosis and anaplasmosis are two tickborne diseases that might not be on your radar, but they should be. In fact, anaplasmosis is now the second most commonly reported tickborne disease after Lyme disease. Tickborne diseases are reported more frequently, and the ranges of certain tick species are expanding, placing more people at risk for tickborne disease. Being aware of the tickborne disease risk in your area and taking key steps to prevent tick bites can help keep you and your family safe this tick season.

Know about tickborne disease risk in your area.

Most of the country, including the Northeast, Midwest, South, and portions of the West are home to one or more tick species known to spread the germs that cause ehrlichiosis and anaplasmosis.

  • Blacklegged and Western blacklegged ticks spread the germ that causes anaplasmosis. Blacklegged ticks in Wisconsin and Minnesota have also been shown to spread an Ehrlichia germ called Ehrlichia muris eauclairensis.

  • Lone star ticks spread two kinds of Ehrlichia germs (Ehrlichia chaffeensis and Ehrlichia ewingii).

Signs and symptoms

Illness typically begins within 1–2 weeks following the bite of an infected tick. Tick bites are usually painless, and many people do not remember being bitten.

Early signs and symptoms of both ehrlichiosis and anaplasmosis usually include:

  • Fever or chills

  • Severe headache

  • Muscle aches

  • Nausea, vomiting, diarrhea, loss of appetite

  • Rash (more common in patients with ehrlichiosis)


Ehrlichiosis and anaplasmosis can become severe when not treated early. See your healthcare provider right away if you develop fever, headache, or rash. Be sure to tell your provider if you remember being bitten by a tick or spending time in areas where ticks may be found. When recognized and treated early, most patients with ehrlichiosis and anaplasmosis will recover fully within days to weeks. The CDC and the American Academy of Pediatrics (AAP) recommend doxycycline as the treatment of choice for ehrlichiosis and anaplasmosis in patients of all ages.

Ticks can be active year-round, but ticks are most active during warmer months (April–September). CDC’s new tick bite data tracker helps track tick bites by region, week, age, and sex.

To learn more visit:

Ehrlichiosis and anaplasmosis | Division of Vector-Borne Diseases | NCEZID | CDC

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