Differential Diagnosis for Fever after Tick Bite
- Single most likely diagnosis
- Lyme disease: This is the most common tick-borne illness in the United States, caused by the bacterium Borrelia burgdorferi. It typically presents with a distinctive rash (erythema migrans), fever, headache, and fatigue after a tick bite.
- Other Likely diagnoses
- Southern tick-associated rash illness (STARI): Characterized by a rash similar to erythema migrans but typically without the distinctive bull's-eye pattern. It's caused by the bite of the lone star tick.
- Ehrlichiosis: A bacterial infection caused by Ehrlichia species, transmitted by the bite of an infected tick. Symptoms include fever, headache, fatigue, and muscle aches.
- Anaplasmosis: Another tick-borne bacterial infection, caused by Anaplasma phagocytophilum. It presents with fever, headache, muscle aches, and can lead to more severe complications if not treated.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Rocky Mountain spotted fever (RMSF): A severe and potentially life-threatening disease caused by Rickettsia rickettsii, transmitted by the bite of an infected tick. Early symptoms include fever, headache, and rash, but it can progress to severe illness if not promptly treated.
- Tularemia: Caused by Francisella tularensis, this bacterial infection can be transmitted through the bite of an infected tick. It presents with fever, skin ulcers, and swollen lymph nodes, and can be life-threatening if not treated.
- Rare diagnoses
- Babesiosis: A parasitic infection caused by Babesia species, transmitted by the bite of an infected tick. It primarily affects red blood cells and can cause anemia, but is less common than other tick-borne illnesses.
- Tick-borne relapsing fever (TBRF): Caused by various Borrelia species, this infection is characterized by recurring episodes of fever, headache, and muscle aches. It's relatively rare and typically associated with the bite of an infected soft tick.
- Powassan virus disease: A rare but potentially severe viral infection transmitted by the bite of an infected tick. It can cause fever, headache, and encephalitis or meningitis in severe cases.