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Illness from Ticks: Human Ehrlichioses

Human ehrlichioses are rickettsial infections caused by at least 3 different species of bacteria called Ehrlichia that are spread to humans through the bites of infected ticks. Most cases occur in the spring and summer months. Infected ticks usually are found in specific areas of the country. The lone star tick is most common in southeastern and south central United States, while deer ticks are common in the northeast and north central United States.

Signs and Symptoms

Although the 3 types of human ehrlichioses are caused by different organisms (Ehrlichia chaffeensis, Ehrlichia ewingii, and Anaplasma), the infections they cause have similar signs and symptoms. These symptoms are similar to those of influenza.

  • Fever
  • Headache
  • Chills
  • Muscle and joint aches and pains
  • A general feeling of sickness (malaise)
  • Loss of appetite

Laboratory abnormalities include

  • Low red blood cell count (anemia)
  • Low white blood cell count (leukopenia)
  • Inflammation of the liver (hepatitis)

In some cases there may be a rash. Nausea and vomiting are common, as well as sudden weight loss because of lack of appetite. On rare occasions, these infections may cause stomach pain, cough, or confusion (a change in mental status).

These symptoms typically begin 5 to 10 days after the tick bite. It is important to remember that tick bites often go unnoticed. Many people with tick-borne infections do not realize that a tick has bitten them.

How Is the Diagnosis Made?

It can be difficult to make a diagnosis of ehrlichioses. There are blood tests that measure antibodies, but these are not generally available. Other blood tests do not give clear results.


Most often, human ehrlichioses is treated with an antibacterial called doxycycline. It should be started immediately after the disease is diagnosed and given orally or intravenously for 5 to 10 days. Although doxycycline and other tetracycline antibacterials are not normally used in children younger than 8 years, in this case, the need for treatment of the bacteria outweighs the small risk of staining the teeth. Currently, there is no effective alternate antibiotic.

What Is the Prognosis?

Most children infected with human ehrlichioses who are treated appropriately will recover without any lasting effects within 1 to 2 weeks. In children with severe cases of the disease, there may be damage to the brain. Without treatment, some patients die from ehrlichioses, although this is rare.


Limit your child’s exposure to ticks as much as possible. In tick-infested areas, he should wear clothing such as long-sleeved shirts and long pants that covers most of his body. Tuck his pants legs into his socks. Apply a repellant containing DEET to the areas of his skin that are exposed, and reapply it every few hours according to the instructions on the product label.

Last Updated
Immunizations & Infectious Diseases: An Informed Parent's Guide (Copyright © 2006 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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