Background: The most common and most recognizable feature of Borrelia burgdorferi infection (Lyme disease) is the skin lesion erythema migrans (EM). An illness associated with an EM-like skin lesion, but which is not caused by B. burgdorferi, occurs in many southern states in the United States (southern tick-associated rash illness [STARI], also known as Masters disease).
Methods: Clinical features of 21 cases of EM-like skin lesions in 21 patients from Missouri were compared in a prospective study with those of 101 cases in 97 patients with EM-like skin lesions from New York.
Results: Among Missouri cases, the peak incidence of EM-like skin lesions occurred earlier in the year than it did among New York cases (P<.001). Case patients from Missouri were more likely to recall a tick bite than were case patients from New York (85.7% and 19.8%, respectively; P<.001), and the time period from tick bite to onset of the skin lesion was shorter among Missouri case patients (6.1+/-4.2 days and 10.4+/-6.1 days, respectively; P=.011). Missouri case patients were less likely to be symptomatic than were New York case patients (19.0% and 76.2%, respectively; P<.001), and Missouri case patients were less likely to have multiple skin lesions (4.8% and 26.7%, respectively; P=.042). EM-like lesions in Missouri cases were smaller in size than those in New York cases (8.3+/-2.2 cm and 16.4+/-11.5 cm, respectively; P<.001), more circular in shape (P=.004), and more likely to have central clearing (76.2% and 21.6%, respectively; P<.001). After antibiotic treatment, Missouri case patients recovered more rapidly than did New York case patients (P=.037).
Conclusion: Cases of EM-like skin lesion in patients from Missouri and New York have distinct clinical presentations.