1. Morphology and Approximate Geographic Distribution of Tick Vectors in the Continental United States The enlarged tick illustrations are sized according to the same scale shown in each panel. The actual size of the ticks are shown in the circles. Top panel, tick vectors for Lyme disease. The morphology of I pacificus is similar to that of I scapularis (shown). Middle panel, tick vector (A americanum) for southern tick-associated rash illness (STARI). Erythema migrans is a manifestation of both Lyme disease and STARI. The ticks in the bottom panel are included for comparison; these ticks are the major vectors of Rickettsia rickettsii, the causative agent of Rocky Mountain Spotted Fever. The morphology of D andersoni is similar to that of D variabilis (shown). Geographic distributions are approximate and will vary over time. The distribution maps are based on data from the Centers for Disease Control and Prevention ( Distribution data for A americanum and D variabilis are updated based on information provided by John F. Anderson, PhD, The Connecticut Agricultural Experiment Station, New Haven (written communication, May 22, 2007).
Source: Erythema Migrans, The Rational Clinical Examination: Evidence-Based Clinical Diagnosis
Citation: Simel DL, Rennie D. The Rational Clinical Examination: Evidence-Based Clinical Diagnosis; 2016 Available at: Accessed: November 13, 2017
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