Differential Diagnosis for Fever

• Single most likely diagnosis
  • Influenza: This is often the first consideration for fever, especially during flu season, due to its high prevalence and contagious nature.
• Other Likely diagnoses
  • Upper Respiratory Tract Infection (URTI): Common colds and other viral infections are frequent causes of fever.
  • Pneumonia: Both bacterial and viral pneumonias can present with fever, cough, and other respiratory symptoms.
  • Urinary Tract Infection (UTI): Especially in women, UTIs are a common cause of fever and can range from cystitis to more severe pyelonephritis.
  • Gastroenteritis: Viral or bacterial infections of the gastrointestinal tract can cause fever, diarrhea, and vomiting.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Meningitis: Although less common, meningitis is a medical emergency that requires prompt diagnosis and treatment to prevent serious complications or death.
  • Sepsis: The body's response to an infection can lead to sepsis, a life-threatening condition that necessitates immediate medical intervention.
  • Appendicitis: Abdominal pain and fever can be symptoms of appendicitis, which requires surgical intervention to prevent rupture and peritonitis.
  • Endocarditis: Infective endocarditis, an infection of the heart valves, is rare but can be fatal if not treated promptly.
• Rare diagnoses
  • Brucellosis: A zoonotic infection that can cause fever, fatigue, and swelling, often related to contact with infected animals or their products.
  • Tuberculosis (TB): While not as common in some regions, TB remains a significant global health issue and can present with fever, weight loss, and cough.
  • Lymphoma: Certain types of lymphoma can present with prolonged fever, night sweats, and weight loss.
  • Autoimmune disorders: Conditions like lupus or rheumatoid arthritis can cause fever, though they are less common causes compared to infectious diseases.