Fever Differential Diagnosis

The differential diagnosis for fever is extensive and can be categorized into several groups. Here's a breakdown of potential causes, organized by their likelihood and potential impact:

• Single Most Likely Diagnosis
  • Viral upper respiratory tract infection (e.g., common cold, influenza): This is often the most common cause of fever, especially in the absence of other specific symptoms. Justification: High prevalence in the general population, especially during seasonal peaks.
• Other Likely Diagnoses
  • Bacterial infections (e.g., pneumonia, urinary tract infections): These are common and can present with fever as a primary symptom. Justification: Fever is a hallmark of bacterial infections, and these conditions are prevalent.
  • Influenza: Especially during flu season, influenza can be a very likely cause of fever. Justification: Seasonal outbreaks and the contagious nature of the virus make it a common cause of fever during certain times of the year.
  • Gastroenteritis: Viral or bacterial infections of the gastrointestinal tract can cause fever. Justification: These infections are common and can lead to significant morbidity.
• Do Not Miss Diagnoses
  • Sepsis: A life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Justification: Although not the most common cause of fever, sepsis is potentially deadly and requires immediate intervention.
  • Meningitis: Infection of the protective membranes covering the brain and spinal cord, which can be viral, bacterial, or fungal. Justification: Meningitis is less common but can be fatal if not treated promptly.
  • Appendicitis: Inflammation of the appendix, which can lead to severe complications if not surgically treated. Justification: Appendicitis is a medical emergency that may initially present with fever and abdominal pain.
  • Endocarditis: Infection of the heart valves. Justification: This condition is less common but can have severe consequences, including heart failure and embolic events.
• Rare Diagnoses
  • Brucellosis: A zoonotic infection that can cause fever, among other symptoms. Justification: While rare, brucellosis can be missed due to its non-specific symptoms and requires specific diagnostic tests.
  • Tuberculosis: A bacterial infection that can affect various parts of the body, often presenting with chronic fever. Justification: Although more common in certain populations (e.g., immunocompromised individuals, those from endemic areas), TB is rare in the general population of many countries but is crucial to diagnose due to its treatability and public health implications.
  • Lymphoma: Certain types of cancer, like lymphoma, can present with fever as an initial symptom. Justification: While rare as a cause of fever, lymphoma is a significant diagnosis that would drastically alter patient management.
  • Factitious fever (Munchausen syndrome): A condition where individuals falsify or induce symptoms, including fever. Justification: Although rare, factitious fever can lead to extensive and unnecessary medical evaluations and treatments.