Ehrlichiosis and anaplasmosis are similar tick-borne illnesses that cause flu-like symptoms, including fever, muscle aches and headache. Signs and symptoms of ehrlichiosis and anaplasmosis usually appear within 14 days after a tick bite.

If treated quickly with appropriate antibiotics, you'll likely recover within a few days. Untreated ehrlichiosis and anaplasmosis can result in serious or life-threatening complications.

The best way to prevent these infections is to avoid tick bites. Tick repellents, thorough body checks after being outside and proper removal of ticks are your best defenses against these tick-borne diseases.


Signs and symptoms of ehrlichiosis and anaplasmosis are generally the same, although they usually are more severe in ehrlichiosis. Symptoms of ehrlichiosis and anaplasmosis, which vary widely from person to person, include:

  • Moderate fever
  • Chills
  • Headache
  • Muscles aches or pains
  • General feeling of being unwell
  • Joint pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Loss of appetite

Additional signs and symptoms associated with ehrlichiosis but rarely with anaplasmosis include:

  • Confusion or changes in mental state
  • Rash

Some people may be infected and not develop symptoms.

When to see a doctor

The time from getting a bite to showing signs and symptoms is usually five to 14 days. If you develop any of the signs or symptoms after a tick bite or after a possible exposure to ticks, see your doctor.


Ehrlichiosis and anaplasmosis are caused by different bacteria.

Ehrlichiosis is caused by different species of ehrlichia bacteria. The Lone Star tick — found in south-central, southeastern and eastern coastal states — is the primary carrier of bacteria causing ehrlichiosis. Black-legged ticks, commonly called deer ticks, in the Upper Midwest are less common carriers.

Anaplasmosis is caused by the bacterium Anaplasma phagocytophilum. It's primarily carried by deer ticks in the Upper Midwest, northeastern states and central Canadian provinces. It's also carried by the Western black-legged tick in Western coastal states and other tick species in Europe and Asia.

The ehrlichia and anaplasma species belong to the same family of bacteria. Although each bacterium appears to have a specific target among immune system cells in the host, all of these infectious agents generally cause the same symptoms.

Tick bites and infection

Ticks feed on blood by latching onto a host and feeding until they're swollen to many times their normal size. Ticks can pick up bacteria from a host, such as a deer, and then spread the bacteria to another host, such as a human. The spread of the bacteria from the tick to the host probably occurs about 24 hours after the tick has begun feeding.

Other ways bacteria spreads

Spread of the bacteria causing ehrlichiosis or anaplasmosis is possible through blood transfusions, from mother to fetus, or through direct contact with an infected, slaughtered animal.

Risk factors

Ticks live near the ground in wooded or brushy areas. They do not fly or jump, so they can only reach a host who brushes up against them. Factors that increase your risk of a tick bite include:

  • Being outdoors in warm spring and summer months
  • Participating in activities in wooded areas, such as camping, hiking or hunting
  • Wearing clothes that leave your skin exposed in tick-friendly habitat


Without prompt treatment, ehrlichiosis and anaplasmosis can have serious effects on an otherwise healthy adult or child. People with weakened immune systems are at a higher risk of more-serious and life-threatening complications.

Complications of an untreated infection may include:

  • Kidney failure
  • Respiratory failure
  • Heart failure
  • Damage to the central nervous system
  • Seizures
  • Coma
  • Severe secondary infections


The best way to steer clear of ehrlichiosis or anaplasmosis is to avoid tick bites when you are outdoors. Most ticks attach themselves to your lower legs and feet as you walk or work in grassy, wooded areas or overgrown fields. After a tick attaches to your body, it usually crawls upward to find a location to burrow into your skin.

If you are going to be working or playing in an area that is a likely tick habitat, follow these tips to protect yourself.

Use tick repellents

  • Spray your outdoor clothing, shoes, tent or other camping gear with a repellent that has 0.5% permethrin. Some gear and clothing may be pre-treated with permethrin.
  • Use an insect repellent registered with the Environmental Protection Agency on any exposed skin, except your face. These include repellents that contain DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone.
  • Do not use products with OLE or PMD on children under age 3.

Dress for protection

  • Wear light-colored clothing that makes it easier for you or others to see ticks on your clothing before they bite.
  • Avoid open-toed shoes or sandals.
  • Wear long-sleeved shirts tucked into your pants and long pants tucked into your socks.

Check for ticks

  • Shower as soon as possible to wash off any loose ticks and check for ticks that may have burrowed.
  • Use a mirror to check your body thoroughly. Pay attention to your underarms, hair and hairline, ears, waist, between your legs, behind your knees, and inside your bellybutton.
  • Check your gear. Dry your clothes and gear on hot for at least 10 minutes to kill ticks before cleaning them.

Other tips

  • Do a daily inspection for ticks on any pet that spends time outdoors.
  • Stay on clear paths as much as possible in wooded and grassy areas.