Differential Diagnosis for a 9-year-old female with a tick bite and bullseye pattern rash, allergic to clav and sulfa abx
- Single most likely diagnosis:
- Lyme disease: This is the most likely diagnosis given the classic bullseye rash (erythema migrans) following a tick bite, which is a hallmark symptom of Lyme disease.
- Other Likely diagnoses:
- Southern tick-associated rash illness (STARI): Although less common than Lyme, STARI can also present with a similar rash after a tick bite, primarily in the southern United States.
- Tick-borne relapsing fever: This condition, caused by various Borrelia species, can present with fever, headache, and a rash, but the rash is not typically a bullseye pattern.
- Do Not Miss diagnoses:
- Rocky Mountain spotted fever (RMSF): Although the rash in RMSF is typically more widespread and petechial, it's crucial to consider this diagnosis due to its high mortality rate if untreated. The presence of a fever, headache, and rash after a tick bite warrants consideration of RMSF.
- Ehrlichiosis/Anaplasmosis: These tick-borne illnesses can present with fever, headache, and sometimes a rash, and can be severe if not treated promptly.
- Rare diagnoses:
- Babesiosis: A parasitic disease transmitted by ticks, babesiosis can cause fever, fatigue, and sometimes a rash, but it's less common and typically presents with more systemic symptoms.
- Tularemia: Caused by Francisella tularensis, tularemia can be transmitted by tick bites and presents with a skin ulcer, fever, and lymphadenopathy, but it's relatively rare and the rash is not typically a bullseye pattern.