The STARI rash is red and expanding, but not as large as the erythema migrans of Lyme disease and fewer lesions are seen. Lyme disease erythema migrans lesions range from 6-28 cm, while STARI erythema migrans lesions are usually 6-10 cm. STARI lesions may be more likely to have central clearing and be more round than those of Lyme disease.
Symptoms of STARI mimic those of early Lyme disease with fatigue, headache, fever, and muscle pains being the most common. No systemic stage is seen in STARI: no cardiac, neurological, or arthritic phases.
The time period between the tick bite and symptoms is shorter with STARI than Lyme disease (about 6 days). Patients diagnosed with STARI erythema migrans have fewer symptoms than those with Lyme disease and patients with STARI recover more quickly after antimicrobial therapy, which is similar to that of Lyme disease (doxycycline and amoxicillin).
Diagnosis is based on symptoms and geography. There are no tests available for diagnosis because the etiological agent is unknown.