Differential Diagnosis for a 2-Day Tick Bite in Utah

Single Most Likely Diagnosis

• Lyme disease: Although less common in Utah compared to other parts of the United States, Lyme disease is still a significant concern following a tick bite. The risk is lower in Utah, but it cannot be ruled out without further testing and clinical evaluation.

Other Likely Diagnoses

• Rocky Mountain Spotted Fever (RMSF): This is a tick-borne illness caused by Rickettsia rickettsii, which is present in Utah. Symptoms can start within a few days of the tick bite and include fever, headache, and rash.
• Colorado Tick Fever: This viral disease is transmitted by the Rocky Mountain wood tick and can cause symptoms such as fever, headache, and body aches. It is more common in the mountainous regions of Utah.
• Tick-borne relapsing fever: Caused by Borrelia species, this disease is transmitted by soft ticks and can lead to recurring episodes of fever, headache, and muscle aches.

Do Not Miss Diagnoses

• Anaplasmosis: Although less common, anaplasmosis is a serious tick-borne disease that can cause severe symptoms, including fever, headache, and in severe cases, respiratory failure. Early diagnosis and treatment are crucial.
• Ehrlichiosis: Similar to anaplasmosis, ehrlichiosis is a potentially severe disease that can cause fever, headache, and fatigue, and can lead to life-threatening complications if not treated promptly.
• Tularemia: Also known as rabbit fever, tularemia is a bacterial infection that can be transmitted by tick bites. It can cause a range of symptoms from mild to severe, including fever, skin ulcers, and pneumonia.

Rare Diagnoses

• Babesiosis: A parasitic disease caused by Babesia microti, transmitted by the black-legged tick. It's rare in Utah but can cause severe anemia and other complications, especially in individuals with weakened immune systems.
• Powassan virus disease: A rare but potentially severe tick-borne viral disease that can cause encephalitis and meningitis. It is less common in Utah but should be considered in the differential diagnosis due to its severity.
• Southern tick-associated rash illness (STARI): Characterized by a distinctive rash, STARI is a rare condition associated with the bite of the lone star tick. It is less common in Utah and its presence is more associated with the southeastern United States.