Differential Diagnosis for Rash with Target Lesion after Tick Bite in Queensland
- Single most likely diagnosis + Southern Tick-Associated Rash Illness (STARI) is less likely in Queensland, however, a similar condition could be considered. The single most likely diagnosis in this context would be Lyme disease-like illness or a similar tick-borne illness endemic to Australia, such as Flinders Island Spotted Fever or Queensland Tick Typhus, given the geographical location and the presentation of a target lesion after a tick bite.
- Other Likely diagnoses + Erythema migrans: Although more commonly associated with Lyme disease, which is less prevalent in Australia, erythema migrans can still occur and presents with a similar target lesion. + Tick-borne spotted fevers: These include diseases like Rickettsial infections, which can present with rash and fever following a tick bite.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.) + Rocky Mountain Spotted Fever (RMSF): Although rare in Australia, RMSF is a potentially fatal disease if not treated promptly. It presents with fever, headache, and a characteristic rash. + Tularemia: Caused by Francisella tularensis, tularemia can be transmitted by tick bites and presents with fever, rash, and ulceroglandular symptoms.
- Rare diagnoses + Babesiosis: A parasitic disease transmitted by ticks, babesiosis can cause fever, hemolytic anemia, and occasionally rash, though it's rare in Australia. + Anaplasmosis: Another tick-borne disease that can cause fever, headache, and rash, though it's less common in the Australian context.
Each of these diagnoses should be considered in the context of the patient's symptoms, travel history, and the endemic diseases of the region. Laboratory testing and clinical evaluation are crucial for making an accurate diagnosis.