Signs and Symptoms

  • Signs and symptoms of ehrlichiosis typically begin within 1-2 weeks after the bite of an infected tick.
    • Tick bites are usually painless, and many people do not remember being bitten.
  • See your healthcare provider if you become ill after being bitten by a tick or spending time in grassy, brushy, wooded areas.

Early Illness

Early signs and symptoms (the first 5 days of illness) are usually mild or moderate and may include:

  • Fever, chills
  • Severe headache
  • Muscle aches
  • Nausea, vomiting, diarrhea, loss of appetite
  • Confusion
  • Rash (more common in children)


Up to 1 in 3 people with ehrlichiosis report a rash; rash is more common in people with E. chaffeensis ehrlichiosis and generally occurs more often in children than adults. Rash usually develops 5 days after fever begins. If a person develops a rash, it can look like red splotches or pinpoint dots.

Late Illness

If antibiotic treatment is delayed, ehrlichiosis can sometimes cause severe illness. Early treatment can reduce your risk of developing severe illness.

Signs and symptoms of severe (late stage) illness can include:

  • Damage to the brain or nervous system (e.g. inflammation of the brain and surrounding tissue (called meningoencephalitis))
  • Respiratory failure
  • Uncontrolled bleeding
  • Organ failure
  • Death

Risk factors for severe illness:

  • Delayed antibiotic treatment
  • Age: being very young or very old
  • Weakened immune system: such as those receiving some cancer treatments, individuals with advanced HIV infection, people who have received organ transplants, or people taking certain medications