Southern tick-associated rash illness

Microbiology

• Unknown; although Borrelia lonestari has been proposed as the causative organism, this has not been confirmed

Epidemiology

• Transmitted by the Lone star tick, Amblyomma americanum, with a presumed deer reservoir
• Present in southern and south-east US

Clinical Manifestations

• Incubation period of 6 to 9 days
• Erythema migrans, similar to Lyme disease

Coinfections

• Human monocytic ehrlichiosis
• Heartland virus
• Q fever

Differential Diagnosis

• Lyme disease

Management

• Reasonable to treat similarly to Lyme disease
• Doxycycline for 10 to 30 days, or amoxicillin, or cefuroxime
• Longer treatment favoured for signs of disseminated disease