Differential Diagnosis for Fever of 3 Weeks
The differential diagnosis for a fever lasting 3 weeks can be extensive and varied, encompassing a wide range of infectious, inflammatory, and neoplastic conditions. Here's a categorized approach to the differential diagnosis:
- Single Most Likely Diagnosis
- Infectious Mononucleosis: Caused by Epstein-Barr virus (EBV), this condition often presents with prolonged fever, sore throat, lymphadenopathy, and fatigue. The duration of fever can vary but often lasts for several weeks.
- Other Likely Diagnoses
- Tuberculosis (TB): A chronic infection caused by Mycobacterium tuberculosis, which can present with fever, night sweats, weight loss, and cough. The onset can be insidious, and symptoms may persist for weeks or even months.
- Endocarditis: An infection of the heart valves, which can cause prolonged fever, new or changing heart murmur, and embolic phenomena. The fever can be persistent and may last for weeks.
- Osteomyelitis: A bone infection that can cause fever, bone pain, and swelling. The fever can persist for weeks if not adequately treated.
- Abscesses: Collections of pus in various parts of the body (e.g., liver, brain, lung) can cause prolonged fever until drained.
- Do Not Miss Diagnoses
- Malignancies (e.g., Lymphoma, Leukemia): Certain cancers can present with prolonged fever, night sweats, and weight loss. Early diagnosis is crucial for treatment and prognosis.
- HIV Infection: The acute retroviral syndrome can present with fever, rash, and lymphadenopathy, and it's critical to diagnose early for appropriate management.
- Brucellosis: A zoonotic infection that can cause undulant fever, night sweats, and joint pains. It's essential to consider in individuals with exposure to animals or their products.
- Fungal Infections (e.g., Histoplasmosis, Coccidioidomycosis): These can cause prolonged fever, especially in immunocompromised individuals or those with specific geographic exposures.
- Rare Diagnoses
- Whipple's Disease: A rare, systemic bacterial infection that can cause fever, weight loss, diarrhea, and arthralgias. Diagnosis is often delayed due to its rarity and nonspecific symptoms.
- Relapsing Fevers (e.g., Borreliosis, Tick-borne): Caused by various bacteria transmitted by ticks or lice, these conditions are characterized by recurring episodes of fever.
- Autoinflammatory Disorders (e.g., Familial Mediterranean Fever): Genetic conditions that cause recurrent episodes of fever and inflammation, often with specific ethnic or familial patterns.
- Kikuchi-Fujimoto Disease: A rare, self-limiting condition that presents with fever, lymphadenopathy, and night sweats, more commonly seen in young Asian women.
Each of these diagnoses requires careful consideration of the patient's history, physical examination, laboratory results, and imaging studies to guide further evaluation and management.