Dermatologic manifestations of arthropod-borne diseases.

The arthropod-borne rickettsial, borrelial, and bacterial diseases of North America are a diverse group of disorders that produce a wide variety of cutaneous abnormalities. These dermatologic abnormalities are often valuable clinical clues that may reveal or suggest the correct diagnosis to the astute clinician. We review the usual and unusual dermatologic manifestations of Rocky Mountain spotted fever, murine and sylvatic typhus, rickettsialpox, ehrlichiosis, Lyme disease, tick-borne relapsing fever, Colorado tick fever, and tularemia. In some of these diseases, skin manifestations may be diagnostic; in others, dermatologic findings may be the initial and only clues that leads to the initiation of life-saving therapy. In other arthropod-borne infections, the appearance or evolution of the skin rash may be characteristic enough to suggest the proper diagnosis.