Approach to Fever and Infection

What can change body temp

Time of day, menstruation, anatomy, hormone

Rank temperature taking location by accuracy

Rectal > oral > axillary > tympanic

Mechanism of heat loss

• Evaporation: sweating and panting

• Convection: increase blood flow

• Conduction: being in contact with colder surface

• Radiation: higher surface area

What is fever

Elevation of body temp that exceed normal variation + increase in hypothalamic set point

What is hyperpyrexia

Fever >41.5C in severe infection and CNS hemorrhage + symptom of organ or system dysfunction

What is hyperthermia

Uncontrolled increase in body temp that exceed ability to lose heat (heat stroke); does NOT respond to antipyretic

Pyrogens

IL1, IL6, TNF alpha, IFN gamma

Autoimmune diseases with fever

Still’s, Behcet, MAS/HLH, gouty arthritis

Associated features of fever

• Rigor, chill or shivering followed by sweating

• Night sweat

• Excessive sweating (TB, infective endocarditis)

• Weight loss TB (consumption)

• Severe headache (meningitis sign)

• Delirium

• Myalgia occur with influenza and meningococcal sepsis

• Joint pain

• Shock (can come with either fever or hypothermia)

What pattern is this

Sustained → Caused by pneumonia, meningitis, UTI, brucella

What pattern is this

Step Ladder (gradually gets higher) → Typhoid and typhus

What pattern is this

Intermittent → caused by deep seated infection, abscess, kala-azar, malignancy, drug fever

What pattern is this

Remittent → Caused by TB, infected endocarditis,

What pattern is this

Relapsing → caused by malaria, borrelia, TB, lymphoma

What pattern is this

Quartan fever → Caused by plasmodium strains every 48, 72 hrs

Clinical symptoms with fever and rash

General maculopapular eruption, confluent desquamative erythema, pustular/vesiculobullous eruption, urticaria like eruption

Factitious fever clues

Patient looks well, bizarre temp, body temp >41, normal ESR and CRP, no sweat, normal temp during observed measurement

What is intermittent fever pattern

Normal circadian exaggeration → Large variation between high and low

What is remittent fever pattern

Temperature spike fall daily with diurnal variation of >2C but doesn’t go down to normal

What is quotidian pattern of fever

Double = two spikes of fever in a day (morning and evening)

Tertian = spike every 48 hr

Quartan = spike every 72 hr