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Acute Fever

Definition and Diagnosis

The average oral temperature for healthy adults is 36.8 ± 0.4°C, with a low point at 6 AM and a peak at 4-6 PM. A morning temperature above 37.2°C and an evening temperature above 37.7°C is often considered as fever. Fever may be continuous, intermittent or remittent. However, due to frequent self-medication with antipyretics, classic patterns are not generally seen.

It is crucial to identify the cause of fever. A detailed history of symptoms, any associated focal symptom(s), exposure to infectious agents and occupational history may be useful. A thorough physical examination repeated regularly may provide potentially diagnostic clues such as rash, lymphadenopathy, hepatomegaly, splenomegaly, abdominal tenderness, altered sensorium, neck stiffness, lung crepts, etc. Drug fever should be considered when the cause of fever is elusive.

Diagnostic Tests

The cause of fever may be from a wide range of diagnoses. If the history and physical examination suggest that it is likely to be more than a simple URI or viral fever, investigations are indicated. The extent and focus of diagnostic work-up will depend upon the extent and pace of illness, diagnostic possibilities and the immune status of the host. If there are no clinical clues, the work-up should include a complete haemogram with ESR, smear for malarial parasite, blood culture, Widal test and urine analysis including urine culture. If the febrile illness is prolonged beyond 2 weeks, an X-ray chest is indicated even in the absence of respiratory symptoms. Any abnormal fluid collection should be sampled. Ultrasonography is needed in some cases of acute fever such as in amoebic liver abscess.

Treatment

Routine use of antipyretics in low-grade fever is not justified as this may mask important clinical indications. However, in acute febrile illnesses suggestive of viral or bacterial cause, fever should be symptomatically treated.

Non-pharmacological: Hydrotherapy with tepid water, rest and plenty of oral fluids.

Pharmacological: Non-specific treatment includes 1. Tab. Paracetamol 500-1000 mg (max 4 g in 24 hours) 6-8 hourly. (Caution: Reduce dose in frail elderly, adults weighing <50 kg and those at risk of hepatotoxicity). And/Or if fever does not come down after 2 hours, 2. .Tab. Ibuprofen 400-600 mg 8 hourly. Specific treatment includes antibiotics/antimalarials depending upon the cause suggested by clinical and laboratory evaluation.

Outcome

In most cases of fever, the patient may either recover spontaneously or a diagnosis is reached after repeated clinical evaluation and investigations. If no diagnosis is reached in up to 3 weeks, the patient is said to be having fever of unknown origin (FUO) and should be managed accordingly.

Patient Education

  • Self-medication and over-medication should be avoided.
  • Avoid injectable paracetamol/NSAIDs.
  • Antibiotics should be taken only on advice of a physician.
  • Avoid covering the patient having high fever with blanket, etc.
  • Plenty of fluids should be taken. Stay in a cool environment. Washing/sponging of face and limbs should be done repeatedly.

References

  1. Alterations in Body Temperature. In: Harrison’s Principles of Internal Medicine. Jameson JL, Fauci AS, Kasper DL, et al (eds), 20th Edition, McGraw Hill Company Inc., New York, 2018; pp. 102-121.
  2. Clinical approach to patient with suspected infection. In: Oxford Textbook of Medicine. Firth J, Conlon C, Cox T (eds), 6th Edition, Oxford University Press, 2020.