Unfortunately, you haven't provided the 3 symptoms for which I should provide a differential diagnosis. However, I can guide you through a general approach to how this would be structured once the symptoms are known. Let's assume we have three symptoms: headache, fever, and confusion.

Differential Diagnosis for Headache, Fever, and Confusion

• Single Most Likely Diagnosis:
  • Viral Meningitis - This is a common cause of headache, fever, and confusion, especially in younger adults. The symptoms align well with the presentation of viral meningitis, which is typically characterized by these symptoms along with stiff neck and photophobia.
• Other Likely Diagnoses:
  • Bacterial Meningitis - Similar to viral meningitis but often more severe and can lead to serious complications if not treated promptly. The presence of fever and confusion, along with headache, makes this a plausible diagnosis.
  • Encephalitis - Inflammation of the brain tissue, usually caused by viral infections. Symptoms can include headache, fever, confusion, and sometimes seizures or difficulties with speech and movement.
• Do Not Miss Diagnoses:
  • Subarachnoid Hemorrhage - Although less common, this condition is life-threatening and requires immediate medical attention. The sudden onset of a severe headache (often described as "the worst headache" ever experienced) along with fever and confusion could indicate a hemorrhage.
  • Brain Abscess - A rare but potentially life-threatening condition that could present with headache, fever, and confusion, especially if the abscess is large enough to cause increased intracranial pressure.
• Rare Diagnoses:
  • Autoimmune Encephalitis - A group of conditions that occur when the body's immune system mistakenly attacks healthy brain cells, leading to inflammation of the brain. Symptoms can include headache, fever, confusion, and sometimes psychiatric symptoms or seizures.
  • Neurosyphilis - A complication of untreated syphilis infection that can occur years after the initial infection, leading to a variety of neurological symptoms including headache, fever, and confusion.

This structure provides a systematic approach to considering potential diagnoses based on the symptoms provided. Each category helps in organizing the thought process, from the most likely to rare conditions, ensuring that critical diagnoses are not overlooked.