Ehrlichiosis and Anaplasmosis Fact Sheet

The Diseases and Transmission

  • Ehrlichia and Anaplasma are related bacteria that are transmitted by ticks. These bacteria infect white blood cells in humans.
  • There are three different bacteria that cause disease in humans: 


Ehrlichia Chaffeensis

Ehrlichia ewingii

Anaplasma Phagocytophilum

(formerly ehrlichichia phagocytophilia)


Human moncytic ehrlichiosis (HME)

Ehrlichiosis ewingii

Human granulocytic anaplasmosis (HGA, formerly HGE)

Tick Vector

Amblyomma Americanum (lone start tick)

Ixodes scapularis (black legged tick)


Southeast and south central US

Northeast and upper Midwest US

  • Animal reservoirs for E. chaffeensis and E. ewingii are white-tailed deer and dogs. The reservoirs for A. phagocytophilum include cattle, deer and rodents. You cannot get the diseases directly from animals.
  • The diseases are not spread between humans other than through blood transfusions.
  • Maryland is home to both the lone star tick and the black-legged tick. 

Symptoms and Treatment


Clinical Features


Ehrlichiosis ewingii

·         Symptoms appear 1 to 2 weeks after a tick bite.

·         Symptoms include fever, headache, muscle aches, nausea, vomiting, diarrhea, confusion, chills and malaise.

·         Conjunctival infection (red eyes)

·         Development of a rash may occur in up to 60% of children and Mountain spotted fever.



·         Symptoms appear 1 to 2 weeks after a tick bite.

·         Symptoms include fever, headache, cough, nausea/abdominal pain, chills, malaise, confusion and muscle aches.

·         Rash is rare



  • Most infections occur when tick activity is highest, in late spring and summer.
  • If left untreated, HME and HGA may be severe.
  • Co-infection with more than one tickborne disease is possible.
  • Persons with compromised immunity caused by immunosuppressive therapies (e.g., corticosteroids, cancer chemotherapy, or longterm immunosuppressive therapy following organ transplant), HIV infection, or splenectomy appear to develop more severe disease.
  • Contact your health care provider if you develop any of these symptoms after a tick bite or after being in tick habitat. Your health care provider may order a blood test to help diagnose the disease.
  • The diseases are effectively treated with antibiotics, most commonly doxycycline.

Prevention Tips

  • Ticks are most active from late spring through early fall
  • Insect repellent containing 20-30% DEET is receommended to prevent tick or fly bites.
  • Repellents with up to 30% DEET can safely be used on children over 2 months of age.
  • Treat clothes with permethrin (don't use permethrin directly on skin).
  • Long pants and long sleeves help keep ticks off of skin, and tucking pant legs into socks and shirts into pants keeps ticks on outside of clothing.
  • Light colored clothing lets you spot ticks more easily.
  • Talk to your veterinarian about tick control products for your pets.
  • When enjoying the outdoors, avoid wooded or brushy areas with tall grass and leaf litter and walk in the center of trails.
  • Check yourself, your kids and your pets daily for ticks when spending time in tick habitat.
  • Bathe or shower as soon as possible after coming indoors (within 2 hours) to wash off ticks.
  • Tumble dry clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothes after you come indoors.

To Remove Ticks

  • Use fine-tipped tweezers.
  • Grab the tick close to the skin; do not twist or jerk the tick.
  • Gently pull straight up until all parts of the tick are removed.
  • Wash your hands with soap and water or an alcohol-based rub.
  • Clean the site of the tick bite with soap and water or an antiseptic.
  • Do not use petroleum jelly, a hot match, nail polish, or other products to remove ticks.

For more information on tick borne diseases, visit: