1. Definition and normal thermoregulation
   • Normal body temperature and diurnal variation
   • Fever vs hyperthermia vs hyperpyrexia
   • Pyrexia of unknown origin (PUO/FUO)
2. Pathophysiology
   • Exogenous and endogenous pyrogens
   • IL-1, IL-6, TNF-alpha, PGE2, hypothalamic set-point
   • Stages of fever: chill, fastigium, defervescence
   • Mechanism of antipyretics
3. Clinical classification
   • By degree and duration
   • Continuous, remittent, intermittent, relapsing, hectic, step-ladder, biphasic patterns
   • Defervescence by crisis vs lysis
4. Approach to a patient with fever
   • Focused history
   • Examination, including danger signs
   • Initial investigations and targeted work-up
   • Differential diagnosis: infectious, inflammatory, malignant, drug-induced, thrombotic, endocrine
5. Fever with key associated findings
   • Fever with rash, lymphadenopathy, hepatosplenomegaly, jaundice
   • Fever with cough, diarrhea, dysuria, headache, altered sensorium, joint pain
   • Fever with thrombocytopenia
   • Fever in returned traveller
6. Special clinical entities
   • FUO/PUO
   • Fever of unknown origin in HIV or immunocompromised patients
   • Neutropenic fever
   • Nosocomial fever
   • Drug fever
   • Factitious fever
7. Management
   • When fever itself needs treatment
   • Non-drug measures and antipyretics
   • When to take cultures and when not to delay antibiotics
   • Sepsis recognition and initial management
   • Indications for admission and emergency referral
8. Special populations
   • Neonates and children
   • Older adults
   • Pregnancy
   • Immunocompromised patients
9. Common viva questions and one-line answers
   • “Why do chills occur?”
   • “Why does sweating occur during defervescence?”
   • “Why is fever useful?”
   • “Why should aspirin be avoided in children?”
   • “Differentiate fever from hyperthermia.”
   • “What is relative bradycardia?”
10. Practical bedside questions

• How to measure temperature correctly
• Temperature sites and their limitations
• Documentation of a fever chart
• Interpretation of fever patterns

50 rapid-fire fever viva questions with answers

1. What is fever?
   Fever is a regulated rise in body temperature due to an increase in the hypothalamic temperature set point, usually in response to pyrogens.
2. What temperature is generally considered fever?
   A measured temperature of 38.0°C or higher is commonly considered fever. Thresholds vary with site and method of measurement.
3. What is the normal body temperature?
   Approximately 37°C, with normal diurnal variation. It is usually lowest in early morning and highest in late afternoon or evening.
4. Which part of the brain regulates body temperature?
   The anterior hypothalamus, especially the preoptic area.
5. What is the difference between fever and hyperthermia?
   In fever, the hypothalamic set point is raised. In hyperthermia, the set point is normal but heat production exceeds heat loss or heat dissipation fails.
6. Give examples of hyperthermia.
   Heat stroke, malignant hyperthermia, neuroleptic malignant syndrome, serotonin syndrome, and sympathomimetic toxicity.
7. What is hyperpyrexia?
   A very high fever, conventionally above 41°C.
8. What are pyrogens?
   Substances that cause fever by raising the hypothalamic set point.
9. What are exogenous pyrogens?
   Pyrogens originating outside the body, classically bacterial products such as lipopolysaccharide or endotoxin.
10. What are endogenous pyrogens?
    Host cytokines released during inflammation, including IL-1, IL-6, TNF-alpha, and interferons.
11. What is the final mediator of fever in the hypothalamus?
    Prostaglandin E2 (PGE2).
12. Describe the mechanism of fever.
    Pyrogens stimulate cytokine release, which increases hypothalamic PGE2. This raises the set point, so the body conserves and generates heat until it reaches the new set point.
13. Why does a patient feel cold during the onset of fever?
    The actual body temperature is below the newly elevated hypothalamic set point, so the body behaves as if it is cold.
14. Why do chills and rigors occur?
    Vasoconstriction reduces heat loss and shivering generates heat to raise body temperature to the new set point.
15. What are the stages of fever?
16. Chill or onset stage
17. Plateau or fastigium
18. Defervescence
19. What happens during defervescence?
    The hypothalamic set point returns toward normal, leading to peripheral vasodilation and sweating to lose heat.
20. What is crisis?
    A sudden fall of fever to normal or subnormal levels, sometimes with marked sweating and possible circulatory collapse.
21. What is lysis?
    A gradual reduction of fever over several days.
22. How do antipyretics reduce fever?
    They inhibit cyclooxygenase and reduce PGE2 production, lowering the hypothalamic set point. Then vasodilation and sweating promote heat loss.
23. Name common antipyretic drugs.
    Paracetamol (acetaminophen) and NSAIDs such as ibuprofen.
24. Why should aspirin generally be avoided in children with viral illness?
    It is associated with Reye syndrome, an acute encephalopathy with hepatic dysfunction.
25. Does every fever require antipyretic treatment?
    No. Treat the patient’s discomfort, hydration status, and underlying cause. Fever itself can be part of an appropriate host response.
26. What are non-pharmacological measures in a febrile patient?
    Oral or intravenous fluids when indicated, light clothing, a comfortable ambient temperature, rest, and treatment of the underlying cause.
27. When is tepid sponging useful?
    It may provide temporary comfort, but it is not routinely necessary and may provoke shivering if the water is too cold.
28. What is fever of unknown origin, or FUO?
    Traditionally, fever of 38.3°C or more on several occasions, lasting more than 3 weeks, with no diagnosis after appropriate evaluation. Modern definitions vary by setting.
29. What are the broad categories of FUO?
    Infections, malignancies, noninfectious inflammatory diseases, and miscellaneous causes such as drug fever or thromboembolism.
30. What is the most important first step in evaluating fever?
    Assess for instability and red flags, then take a careful history and perform a focused examination for localizing signs.
31. What history is important in fever?
    Duration and pattern, travel, contacts, occupation, animal or insect exposure, food and water exposure, drug history, surgery, devices, immunosuppression, sexual history, and localizing symptoms.
32. What examination findings should be actively sought?
    Rash, lymphadenopathy, hepatosplenomegaly, cardiac murmur, joint swelling, spine tenderness, focal neurological signs, meningeal signs, wound infection, and indwelling-line infection.
33. What are red flags in a patient with fever?
    Altered mental status, hypotension, dyspnea, marked tachypnea or tachycardia, petechial or purpuric rash, severe headache with neck stiffness, temperature above 40°C, and immunocompromise.
34. What initial investigations may be considered in undifferentiated significant fever?
    CBC with differential, renal and liver function tests, urinalysis, cultures when indicated, chest radiograph if respiratory features exist, and targeted tests guided by history and examination.
35. When should blood cultures be obtained?
    Before antibiotics when bloodstream infection, sepsis, infective endocarditis, or severe unexplained fever is suspected, provided this does not delay urgently needed treatment.
36. Should antibiotics be prescribed for every fever?
    No. Antibiotics are indicated for suspected or confirmed bacterial infection, not for uncomplicated viral illness or fever without evidence of bacterial disease.
37. What is sepsis?
    Sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection.
38. What should be done if fever is accompanied by hypotension, confusion, or respiratory distress?
    Treat it as a potential emergency: assess airway, breathing, circulation, obtain urgent senior or emergency care, take cultures where feasible, measure relevant labs including lactate, give fluids when appropriate, and start timely antimicrobials if infection is suspected.
39. What is a fever pattern?
    The characteristic variation in temperature over time. It can suggest possibilities but is rarely diagnostic on its own.
40. What is continuous fever?
    Temperature remains above normal throughout the day with minimal fluctuation, classically less than 1°C in 24 hours.
41. What is remittent fever?
    Temperature fluctuates by more than 1°C in 24 hours but does not return to normal.
42. What is intermittent fever?
    Temperature rises for a period and returns to normal at least once within 24 hours.
43. What is relapsing fever?
    Febrile episodes alternate with afebrile intervals of days or weeks.
44. What is hectic fever?
    A fever with wide daily fluctuations, often accompanied by chills and sweating. It may occur in severe infections, abscesses, and some inflammatory disorders.
45. What is a step-ladder fever pattern?
    A progressive, stepwise daily rise in temperature. It is traditionally associated with enteric fever but is neither sensitive nor specific.
46. What is a saddleback or biphasic fever?
    Fever subsides and then recurs after a short afebrile interval. It can occur in some viral infections, including dengue, but is not diagnostic.
47. What is relative bradycardia?
    Pulse rate that is lower than expected for the degree of fever. It may be seen in typhoid fever, brucellosis, leptospirosis, psittacosis, drug fever, and some viral infections.
48. What is drug fever?
    Fever caused by a medication, often through hypersensitivity or idiosyncratic mechanisms, which resolves after withdrawal of the responsible drug.
49. Name drugs that can cause drug fever.
    Beta-lactam antibiotics, sulfonamides, anticonvulsants such as phenytoin and carbamazepine, procainamide, quinidine, amphotericin B, and interferons.
50. What clues suggest drug fever?
    Fever temporally related to a new drug, relative bradycardia, rash, eosinophilia, absence of a clear infective source, and resolution after stopping the suspected drug.
51. Why can fever be absent in serious infection in older adults?
    Older adults may have impaired thermoregulatory and immune responses, so sepsis may present with confusion, weakness, hypothermia, or functional decline instead.
52. Why is fever in a young infant important?
    Young infants can have serious bacterial infection with few localizing signs. A measured fever, especially in infants under 3 months, requires prompt medical assessment.
53. What is the key principle in management of fever?
    Treat the cause, not merely the temperature. Assess severity, identify or exclude dangerous infection and noninfectious causes, maintain hydration and comfort, and use antimicrobials only when clinically indicated.