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JAMA Patient Page
November 10, 2004


JAMA. 2004;292(18):2302. doi:10.1001/jama.292.18.2302

Ticks carry bacteria that can cause human disease. Ehrlichiosis, Rocky Mountain spotted fever, and Lyme disease are infectious diseases transmitted by tick bites. The Lone Star tick carries Ehrlichia chaffeensis (named to honor bacteriologist Paul Ehrlich), the bacteria that causes human monocytic ehrlichiosis. Another type of tick, the deer tick, carries the bacteria responsible for another type of ehrlichiosis, called human granulocytic ehrlichiosis. Deer ticks also carry the organism that causes Lyme disease. The November 10, 2004, issue of JAMA includes an article about ehrlichiosis.

Symptoms and signs of ehrlichiosis

  • Fever

  • Headache

  • Joint pain

  • Nausea or vomiting

  • Malaise (feeling ill)

Although redness of the skin is common in ehrlichiosis, there is no distinctive rash. In contrast, Lyme disease usually begins with a spreading rash, called erythema migrans. If not treated, ehrlichiosis can progress to a severe illness.

Testing for ehrlichiosis

The symptoms of ehrlichiosis are similar to those of viral illnesses and other bacterial infections. In addition to a careful medical history and physical examination, testing for ehrlichiosis may include blood counts (looking for a low white blood cell and low platelet count), and liver enzyme blood tests. Special staining of a blood smear can show the actual Ehrlichia organisms. More sophisticated laboratory testing may be done to confirm the diagnosis.


Antibiotic treatment, usually with doxycycline, is effective for ehrlichiosis. If recognized and treated early, the infection responds quickly to doxycycline therapy. Supportive care may be needed in advanced cases, including hospitalization and possibly intensive care. Pregnant women should not take doxycycline, which is a member of the tetracycline family of antibiotics. Other types of antibiotics may be used to treat pregnant women or individuals allergic to tetracycline.

Preventing ehrlichiosis

All tick-borne diseases can be prevented using the same measures. Wearing long pants and long sleeves, tucking pants into boots or socks, wearing light-colored clothing, and using hats and gloves are all ways to protect yourself against ticks. If you are outdoors in a known tick-infested area, check yourself for ticks and remove them as soon as you see them. Because there is a delay between the time of a tick bite and transmission of the disease-causing bacteria from the tick, removing ticks quickly may help prevent infection. Using an insect repellent containing DEET (diethyl-meta-toluamide) is an effective way to repel ticks. It is important to follow the instructions on the label of any DEET-containing product.

For more information

Inform yourself

To find this and previous JAMA Patient Pages, go to the Patient Page link on JAMA's Web site at http://www.jama.com. Many are available in English and Spanish. A Patient Page on Lyme disease was published in the February 2, 2000, issue.

Sources: Centers for Disease Control and Prevention, American Lyme Disease Foundation, National Institute of Allergy and Infectious Diseases

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. Any other print or online reproduction is subject to AMA approval. To purchase bulk reprints, call 718/946-7424.