Differential Diagnosis for Tick-Borne Disease with Skin Ulcer in Florida

• Single Most Likely Diagnosis
  • Southern Tick-Associated Rash Illness (STARI): This condition is characterized by a distinctive rash that can resemble a bull's-eye and is often accompanied by an ulcer at the site of the tick bite. It's transmitted by the lone star tick, which is common in Florida.
• Other Likely Diagnoses
  • Lyme Disease: Although less common in Florida compared to other parts of the United States, Lyme disease can cause a skin rash (erythema migrans) that may resemble an ulcer. It's transmitted by the black-legged tick.
  • Tularemia: This bacterial infection can cause an ulceroglandular form, characterized by an ulcer at the site of the tick bite, along with swollen lymph nodes. It's found in Florida and is transmitted by various ticks, including the lone star tick and the American dog tick.
• Do Not Miss Diagnoses
  • Rocky Mountain Spotted Fever (RMSF): Although rare in Florida, RMSF is a potentially deadly disease that can cause a rash and, in some cases, an eschar (a dark, scab-like lesion) at the site of the tick bite. It's transmitted by the American dog tick, the brown dog tick, and the lone star tick.
  • Ehrlichiosis: This bacterial infection can cause severe illness and, in rare cases, may present with a rash or an eschar. It's transmitted by the lone star tick and the black-legged tick.
• Rare Diagnoses
  • Southern Tick-Associated Alpha-Gal Syndrome: This is a rare condition associated with the lone star tick, which can cause an allergic reaction to red meat. While it doesn't typically cause an ulcer, it's a consideration in patients with tick exposure in Florida who develop unusual symptoms after eating red meat.
  • Tick-Borne Relapsing Fever (TBRF): This disease is rare in Florida but can be transmitted by soft ticks. It's characterized by recurring episodes of fever and can cause a variety of symptoms, including rash, but is less commonly associated with skin ulcers.