What is ehrlichiosis?

Ehrlichiosis is a tick-borne disease caused by bacteria named Ehrlichia. Ehrlichia bacteria are transmitted by lone star ticks and infect human white blood cells. Ehrlichiosis is a relatively new tick-borne disease; the first human case was identified in 1986. Next to Lyme disease, it is the second most common tick-borne disease to affect persons in Virginia.

Who gets ehrlichiosis?

Anyone can get ehrlichiosis, 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?

Ehrlichiosis may be mild to moderately severe, 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.

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.

How is the disease spread?

The bacteria are transmitted to humans by the bites of infected lone star ticks. Ehrlichiosis cannot be transmitted from person to person. 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.

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 can be a severe or fatal illness, so treatment should be given based on suspicion of illness, and not be delayed until laboratory results are complete.

How can I prevent ehrlichiosis?

Avoiding the bites from lone star ticks will prevent ehrlichiosis. Lone star 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 lone star 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; 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 because ehrlichiosis transmission can occur once ticks have been attached for more than 24 hours. 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?


May 2013