Adult female and nymph (inset photo) Lone Star Ticks transmit Ehrlichiosis (Photo: Bill Eaker)
Adult female and nymph (inset photo) Lone Star Ticks transmit Ehrlichiosis (Photo: Bill Eaker)

What is Ehrlichiosis?

Ehrlichiosis is a tick-borne disease caused by bacteria named EhrlichiaEhrlichia bacteria are transmitted by lone star ticks and infect human white blood cells.  Ehrlichiosis is a relatively newly discovered tick-borne disease; the first human case was identified in 1986.  Next to Lyme disease, it is the second most confirmed tick-borne disease to affect persons in Virginia.  Ehrlichiosis cases are most common in the low elevation areas east of the Blue Ridge mountains (areas below 1,500 feet elevation) because lone star ticks are the predominant cause of tick bites in this parts of Virginia.

What is Anaplasmosis?

Anaplasmosis is a tick-borne disease similar to ehrlichiosis but it is caused by a different closely related bacterium (Anaplasmosis phagocytilum) and is transmitted to humans by blacklegged ticks (the same tick species that can carry Lyme disease).  Cases of anaplasmosis are not nearly as common as cases of ehrlichiosis in Virginia.

Adult female and nymph (inset photo) Blacklegged Ticks transmits Anaplasmosis (Photo: Graham Hickling)
Adult female and nymph (inset photo) Blacklegged Ticks transmits Anaplasmosis (Photo: Graham Hickling)

Who gets Ehrlichiosis/Anaplasmosis?

Anyone can get ehrlichiosis or anaplasmosis, but the majority of cases are seen in adults.  Anyone who spends time in tick-infested forest areas in the period from April through August is at greatest risk of exposure.

What are the symptoms of Ehrlichiosis/Anaplasmosis?

Ehrlichiosis may be a mild to moderately severe illness, but can be life-threatening or fatal.  Illness may cause a fever, and at least one or more of the following symptoms:  headache, chills, discomfort, muscle pain, nausea, vomiting, diarrhea, confusion, a rash and red eyes.  The rash may appear in up to 30% of infected adults and 60% of infected children.  The rash may be similar to the rash caused by Rocky Mountain spotted fever.  Patients with severe illness may develop difficulty breathing, bleeding disorders, or neurologic problems.  Patients often develop a low white blood cell count, a low platelet count, and elevated liver enzyme levels.  The initial symptoms of ehrlichiosis are very similar to those of anaplasmosis and Rocky Mountain spotted fever, so those illnesses should also be considered in the diagnosis.

Symptoms of anaplasmosis can include fever, headache, muscle pain, vomiting, general discomfort, malaise, chills, nausea, cough, and occasionally a rash (rashes are rare with anaplasmosis). If not treated, anaplasmosis can be severe and sometimes fatal. Severe illness symptoms are similar to those of ehrlichiosis: difficulty breathing, hemorrhage, renal failure or neurological problems.

When do symptoms appear?

Persons generally become ill about one to two weeks after an infectious tick bite.  Not every exposure to an infected tick results in infection.  Infected ticks must be attached for at least 24 hours to transmit either ehrlichiosis or anaplasmosis.

How is the disease spread?

The bacteria of both diseases are transmitted to humans by the bites of infected ticks. Anaplasmosis is spread by infected blacklegged ticks. Ehrlichiosis is spread by infected lone star ticks. Lone star ticks are the most common tick to bite people in Virginia, and as many as 1 in 20 lone star ticks (5%) may be infected with an Ehrlichia agent. Ehrlichiosis and anaplasmosis cannot be transmitted from person to person.

What is the treatment?

Prompt treatment (in the first five days of illness) with an appropriate antibiotic (doxycycline) will minimize the chances of a severe illness development, and usually results in a rapidly effective cure.   Ehrlichiosis  and anaplasmosis can be severe or fatal, so treatment should be given based on suspicion of illness, and not be delayed until laboratory results are complete.

How can I prevent Ehrlichiosis/Anaplasmosis?

Avoiding the bites from ticks will prevent ehrlichiosis and anaplasmosis.  Ticks primarily live in forest habitats (i.e., in forest leaf litter, along the edges of forest, or in fields under the shade of trees).  When working or playing in tick habitats, wear light-colored clothing, tuck pants into socks, and tuck shirt into pants; wear clothing, shoes and socks that have been treated with (permethrin) repellents for clothing; apply other repellents containing active ingredients such as DEET, Picaridin, oil of lemon eucalyptus, Bio-UD, or IR3535 to exposed skin (check the fine print at the bottom of a repellent label to determine the active ingredient).  Use “skin” repellents sparingly and avoid prolonged or excessive applications, especially on children.  Check clothes and body surfaces carefully to remove ticks soon after being in tick habitats.

How should a tick be removed?

Remove attached ticks as soon as possible.  Use fine-tipped tweezers to grab the tick’s head as close to the skin as possible and exert a steady pull until the tick lets go.  Do not jerk or twist the tick out, or squeeze the tick’s body when removing it.  The species identity of a tick will provide important clues as to what types of diseases it might carry, so you may want to save the tick for identification by placing it in a jar or plastic bag.  The tick may be frozen or placed in alcohol to preserve it.

How can I learn more about Ehrlichiosis and Anaplasmosis?

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You may also call your local health department if you have questions or concerns about ehrlichiosis. A directory of local health departments is located at: