Lyme disease has long been associated with the appearance of a circular rash radiating out from the site of an infected tick bite, known as an erythema migrans (EM) rash. The best-known EM rash is the so-called "bull's-eye" or target rash, which consists of concentric circles of redness around a central clearing. Unfortunately, not all patients notice any kind of rash. First, scientists believe that some strains of Lyme do not produce a rash at all. Second, ticks often bite the scalp, behind the ears, in the middle of the back, or other places that are hard for a patient to inspect. Finally, not all EM rashes look like the classic "bull's-eye" rash since many other variations are now being reported.
In fact, Harvard Medical School professor Dr. Jonathan Edlow reported in 2002 that the target or "bull's-eye" is no longer considered the most common type of rash associated with Lyme disease. EM rashes can be uniform in color, oozing, blistered, scaly, and in a variety of shapes. They can range from a pink color to shades of deep red, purple, or brown. Occasionally an EM rash is warm to the touch or burning, itching, or painful. A so-called mini-EM rash with a diameter of 5 cm or less has been reported in Europe. Some doctors think that multiple rashes appearing on different parts of the body is a sign of rapidly-spreading infection.
The EM rash may appear as a dark bruise on dark skin, as some of the pictures from the Lyme Disease Foundation demonstrate (please see http://www.lyme.org/gallery/em_patmas3.html and http://www.lyme.org/gallery/emmasters.html for examples. Other frequent misdiagnoses include ringworm, cellulitis, and spider bites.
According to the Centers for Disease Control, the EM rash is noticed in 70 to 80 percent of persons who contract Lyme disease. However, other studies have suggested that this percentage may be as low as 50 percent or less. EM rashes may appear in a few days or several weeks after the bite and may recur with antibiotic treatment.
Co-infections of Lyme can also cause rashes. Rocky Mountain Spotted Fever is famous for the spotted rash it produces on the hands and feet along with fever and virus-like symptoms. RMSF can be fatal if treatment is not given promptly. Bartonella or cat scratch disease can cause pink or purple streaks in the skin which resemble stretch marks. Finally, tularemia can cause ulcerated sores at the site of the tick bite. Other dermatological manifestations of these infections are possible.
Although not every tick-borne infection causes rashes, many do. Therefore, patients should seek immediate medical care if any kind of rash appears anywhere on the body after exposure to ticks.
A picture is worth a thousand words!
Now that you have read some facts about Lyme-induced EM rashes, please visit these sites to see the wide variety of forms the EM rash may take.
The Johns Hopkins University Dermatological Atlas
The Centers for Disease Control Lyme Disease Rash Photos The Lyme Disease Foundation Lyme Rash Photo Gallery
Please see the "Dermatologic findings" under the Physical Examination section of Dr. Jonathan Edlow's eMedicine article http://www.emedicine.com/emerg/topic588.htm
Images of Lyme disease rashes and other symptoms, compiled by the Hardin Library for the Health Sciences at the University of Iowa http://www.lib.uiowa.edu/hardin/md/lymediseasepictures.html
Please visit the LDF's photos of other manifestations of Lyme disease at http://www.lyme.org/gallery/other_symptoms.html
Download PDF Version: Rashes Associated With Lyme Disease
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