Differential Diagnosis for Fever of 3 Days with Increase at Night

Given that malaria and dengue are negative, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Tuberculosis (TB): TB is a common cause of prolonged fever, especially in regions where it is endemic. The fever can be low-grade and typically increases at night, which aligns with the symptoms described. TB can affect various parts of the body, including the lungs, and its diagnosis requires a combination of clinical suspicion, imaging, and microbiological confirmation.
• Other Likely Diagnoses
  • Urinary Tract Infection (UTI): UTIs can cause fever that worsens at night. While they are more common in women, men and children can also be affected. The diagnosis is typically made through urinalysis and culture.
  • Pneumonia: Community-acquired pneumonia can present with fever, which may worsen at night, along with cough, sputum production, and shortness of breath. Diagnosis is made through clinical examination, chest X-ray, and sometimes blood cultures.
  • Typhoid Fever: Caused by Salmonella Typhi, typhoid fever is characterized by prolonged fever, headache, and abdominal pain. The fever typically increases in a stepwise fashion and can be worse at night. Diagnosis is through blood culture or the Widal test.
• Do Not Miss Diagnoses
  • Endocarditis: Infective endocarditis is a serious condition where the inner lining of the heart, particularly the heart valves, becomes infected. It can present with prolonged fever, among other symptoms. Diagnosis is crucial as it requires prompt antibiotic treatment and sometimes surgery.
  • Meningitis: Although less common, meningitis (inflammation of the protective membranes covering the brain and spinal cord) can present with fever, headache, and stiff neck. It is a medical emergency requiring immediate diagnosis and treatment.
  • Sepsis: Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Fever is a key component, and early recognition and management are critical.
• Rare Diagnoses
  • Brucellosis: A zoonotic infection that can cause undulant fever, among other symptoms. It's rare in many parts of the world but should be considered in individuals with exposure to infected animals or their products.
  • Lymphoma: Certain types of lymphoma can present with prolonged fever, known as "B symptoms" when accompanied by night sweats and weight loss. Diagnosis requires imaging and biopsy.
  • ** Familial Mediterranean Fever**: A genetic disorder that causes recurrent episodes of painful inflammation in the abdomen, chest, or joints, often accompanied by fever. It's rare and mostly found in populations from the Mediterranean region.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and appropriate diagnostic tests to confirm the cause of the fever.