Differential Diagnosis for Fever, Pharyngitis, Headache, Rash, and Pain with Eye Movement

• Single Most Likely Diagnosis
  • Infectious Mononucleosis (Mono): This condition, caused by Epstein-Barr virus (EBV), often presents with fever, sore throat (pharyngitis), headache, and sometimes a rash, especially if the patient is taking ampicillin. The pain with eye movement could be related to the general malaise or specific involvement of the eyes in more severe cases.
• Other Likely Diagnoses
  • Streptococcal Pharyngitis: While primarily causing a sore throat, streptococcal infections can also lead to fever, headache, and sometimes a rash. The pain with eye movement might be less directly related but could occur due to the systemic nature of the infection.
  • Viral Exanthems: Various viral infections can cause rashes, fever, and systemic symptoms like headache and pharyngitis. The specific virus (e.g., enterovirus, adenovirus) might influence the exact presentation.
  • Influenza: Especially during flu season, influenza can present with fever, headache, sore throat, and body aches, which might include pain with eye movement due to the systemic nature of the illness.
• Do Not Miss Diagnoses
  • Meningitis: Although less common, meningitis (inflammation of the protective membranes covering the brain and spinal cord) is a critical diagnosis not to miss. It can present with fever, headache, and neck stiffness (which might cause pain with eye movement). A rash can be present in meningococcal meningitis.
  • Lyme Disease: In endemic areas, Lyme disease can cause fever, headache, rash (characteristic "bull's-eye" rash), and systemic symptoms. While less common, it's a diagnosis that should be considered to avoid missing a treatable condition.
  • Rocky Mountain Spotted Fever (RMSF): This tick-borne illness can present with fever, headache, rash, and sometimes pharyngitis. It's crucial to diagnose promptly due to the potential for severe outcomes if not treated early.
• Rare Diagnoses
  • Kawasaki Disease: An acute febrile illness of childhood that presents with fever, rash, conjunctivitis (which could cause pain with eye movement), and other systemic symptoms. It's rare but important to consider due to the risk of cardiac complications.
  • Ehrlichiosis/Anaplasmosis: These are tick-borne diseases that can cause fever, headache, rash, and systemic symptoms. They are less common but should be considered in patients with a history of tick exposure, especially in endemic areas.