Differential Diagnosis for Tick Bite with Small Red Rash/Bull's Eye Around Site
- Single most likely diagnosis
- Lyme disease: This is the most likely diagnosis due to the characteristic bull's eye rash (erythema migrans) that appears at the site of the tick bite, which is a hallmark symptom of Lyme disease.
- Other Likely diagnoses
- Southern tick-associated rash illness (STARI): This condition also presents with a rash similar to erythema migrans, but it is not caused by the bacteria that causes Lyme disease.
- Tick-borne relapsing fever: Although less common, this disease can cause a rash and is transmitted by ticks, making it a possible diagnosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Rocky Mountain spotted fever: This disease is transmitted by ticks and can be fatal if not treated promptly, making it a critical diagnosis not to miss, despite its lower likelihood.
- Tularemia: Another tick-borne disease that can be severe and even fatal if not treated, thus it should not be overlooked.
- Rare diagnoses
- Babesiosis: A rare disease caused by a parasite transmitted by ticks, which can cause a rash among other symptoms, but is less common than other tick-borne illnesses.
- Ehrlichiosis: A bacterial infection transmitted by ticks that can cause a rash, though it is less frequently associated with a bull's eye rash compared to Lyme disease.