Southern Tick-Associated Rash Illness (STARI), produces an expanding bull’s eye rash similar to the rash of Lyme disease. It is sometimes referred to as Masters Disease, in honor of Edwin Masters, the Missouri family physician who first reported these cases to his state’s Department of Health. This disease has been described in humans following bites of the Lone Star tick (Amblyomma americanum). The distribution, range and abundance of the lone star tick has increased over the past 20-30 years, and Lone Star ticks have been recorded in large numbers in the southern United States; as far north as Maine and as far west as central Texas and Oklahoma. All three life stages of A. americanum aggressively bite people. The causative pathogen of STARI has not yet been determined, though Borrelia lonestari has been suspected in past research.
The lone star tick is considered a rare visitor in Colorado. STARI is not a reportable disease in Colorado and no cases of STARI have been documented in Colorado to date.
The primary diagnostic symptom of STARI is a red, expanding “bull’s-eye” lesion that develops around the site of a Lone star tick bite. The rash usually appears within 7 days of tick bite and expands to a diameter 3 inches or more. The saliva from lone star ticks can be irritating; redness and discomfort at a bite site does not necessarily indicate an infection.
In addition to rash, symptoms may also include:
- Muscle pain
In a study that compared physical findings from STARI patients in Missouri with Lyme disease patients in New York (Wormser et al, 2005), several key differences were noted:
- Patients with STARI were more likely to recall a tick bite than were patients with Lyme disease.
- The time period from tick bite to onset of the skin lesion was shorter among patients with STARI (6 days, on average).
- STARI patients with an Erythema Migrans (EM-bull’s eye) rash were less likely to have other symptoms than were Lyme disease patients with erythema migrans rash.
- STARI patients were less likely to have multiple skin lesions, had lesions that were smaller in size than Lyme disease patients, and had lesions that were more circular in shape and with more central clearing.
- After antibiotic treatment, STARI patients recovered more rapidly than did Lyme disease patients.
STARI is diagnosed on the basis of symptoms, geographic location, and possibility of tick bite. Because the cause of STARI is unknown, no diagnostic blood tests have been developed. Researchers have hypothesized that STARI was caused by the spirochete, Borrelia lonestari; however, further research has not confirmed. Despite vigorous efforts, the causative agent of STARI has never been cultured.
There are currently no diagnostic tests available for STARI as the pathogen responsible for this illness has not been conclusively identified.
It is not known whether antibiotic treatment is necessary or beneficial for patients with STARI. However, because STARI resembles early Lyme disease, physicians will often treat patients with oral antibiotics.