Human ehrlichiosis is caused by at least three distinct kinds of bacteria that are transmitted by tick bites: Ehrlichia chaffeensis, Ehrlichia ewingii, and Anaplasma phagocytophilum

Lone star ticks (Amblyomma americanum), called for the solitary white dot on their backs, are the principal source of ehrlichiosis in humans. Furthermore, lone star ticks are aggressive human biters, and they are the most frequent tick to attack people in the southern and south central United States. 

Moreover, dog ticks (Dermacentor variabilis) and deer ticks (Ixodes scapularis) may be infected with and transmit the bacterium that causes human ehrlichiosis.


Typically, signs and symptoms of ehrlichiosis manifest within one to two weeks following a tick bite.

Early Illness

Early signs and symptoms of Human Ehrlichiosis include:

  • Muscle aches
  • Severe headache
  • Muscle aches
  • Nausea
  • Chills
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Confusion
  • Fever
  • Rash 

Late Illness

Ehrlichiosis can occasionally result in serious illness if antibiotic treatment is postponed. Your chance of becoming seriously ill can be decreased by receiving early treatment.

Severe (late-stage) disease may manifest as the following signs and symptoms:

  • Brain damage
  • Uncontrolled bleeding
  • Organ failure
  • Respiratory failure
  • Death


Your medical professional will inquire about your symptoms and medical background. If you know that a tick recently bit you, tell your doctor. In regions of the country where these ticks are prevalent, your healthcare physician could inquire about how much time you spend outside. Also required is a physical examination.

To diagnose the problem, your healthcare professional will need the results of specific tests. These could consist of blood tests to look for:

  • Polymerase chain reaction. 
  • Indirect immunofluorescent assay 
  • Blood sample to examine white blood cells 
  • Antibody testing


If your doctor suspects ehrlichiosis, he or she may prescribe medicine before obtaining the test results.

For 10 to 14 days, an antibiotic will be administered. The most usually recommended antibiotic for ehrlichiosis is doxycycline (Acticlate). If you are pregnant, your physician may prescribe other antibiotics, like rifampin (Rifadin).

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