Differential Diagnosis for Tick Bite in a 6-Year-Old

Single Most Likely Diagnosis

• Lyme Disease: This is the most common tick-borne illness in the United States, particularly in children. The initial presentation often includes a distinctive "bull's-eye" rash (erythema migrans) at the site of the tick bite, along with possible symptoms like fever, headache, and fatigue.

Other Likely Diagnoses

• Southern Tick-Associated Rash Illness (STARI): Although less common than Lyme disease, STARI can present with a similar rash and is associated with the lone star tick. It's essential to consider this diagnosis, especially in regions where the lone star tick is prevalent.
• Ehrlichiosis: This bacterial infection, transmitted by the lone star tick and blacklegged tick, can cause fever, headache, and fatigue. It's more likely in areas where these ticks are common.
• Anaplasmosis: Similar to ehrlichiosis, anaplasmosis is a bacterial infection that can result from a tick bite, leading to symptoms like fever, headache, and muscle pain.

Do Not Miss Diagnoses

• Rocky Mountain Spotted Fever (RMSF): Although less common, RMSF is a severe and potentially life-threatening disease that requires prompt treatment. It's characterized by fever, headache, and a rash, and is transmitted by the American dog tick, Rocky Mountain wood tick, and brown dog tick.
• Tularemia: This rare but serious bacterial infection can be transmitted by tick bites. Symptoms include fever, skin ulcers, and swollen lymph nodes. Given its potential severity, it's crucial not to miss this diagnosis.
• Babesiosis: A parasitic infection that can be life-threatening, especially in individuals with weakened immune systems. It's transmitted by the blacklegged tick and can cause symptoms like fever, chills, and anemia.

Rare Diagnoses

• Powassan Virus Disease: A rare but potentially severe viral infection transmitted by the blacklegged tick. Symptoms can range from mild (fever, headache) to severe (encephalitis, meningitis).
• Tick-Borne Relapsing Fever (TBRF): Caused by various species of Borrelia spirochetes, TBRF is characterized by recurring episodes of fever, headache, and muscle pain. It's more commonly associated with soft ticks and is rare in the context of hard tick bites.
• Colorado Tick Fever: A viral infection transmitted by the Rocky Mountain wood tick, characterized by fever, headache, and body aches. It's relatively rare and mostly confined to the western United States.