Differential Diagnosis for Fever

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.
  • Lymphoma: Certain types of cancer, like lymphoma, can present with fever as an initial symptom. Justification: Although rare as a cause of fever, lymphoma is a significant diagnosis that should not be overlooked.
  • Autoimmune disorders (e.g., lupus, rheumatoid arthritis): These can cause periodic fevers. Justification: While not common causes of fever, autoimmune disorders can have a wide range of symptoms, including fever, and are important to consider in the differential diagnosis.
  • Factitious fever (induced by the patient themselves): This is a rare condition where a patient intentionally produces or falsifies fever. Justification: Important to consider, especially in patients with a history of factitious disorder.