Fever

What is fever?

A fever is an increase in body temperature above normal in response to an infection, inflammation, drug reactions, or other disease conditions such as cancer and arthritis.

In figure, an oral and rectal temperature measurements of 38ºC and 38.2ºC respectively or more is fever.

Fever is also called a high temperature, hyperthermia, or pyrexia.
It is a leading cause for seeking medical care globally.

In health, temperature is controlled within limits (in adults at a mean of 36.8C) with diurnal variations of about 0.5C.

Fever is elevation of body temperature that exceeds the normal daily variation and occurs in conjunction with an increase in hypothalamic set point.

In children younger than 5 years of age, fever is:

A rectal temperature greater than 38ºC
Oral temperature above 37.8ºC
Axillary temperature above 37.2ºC

Important points in the history are:

Chronology of symptoms
Occupational history
Travel history
Family history
Geographic region
Physical examination:
- Vital signs (axillary temperatures are unreliable)
Skin, lymph nodes, eyes, nail beds, CNS, chest, abdomen, cardiovascular, musculoskeletal and nervous systems
Rectal examination is imperative
Pelvic examination (for women)
The penis, prostate, scrotum and testes (for men)

Causes of fever

Fever is caused by the following;

Infections
Inflammation
Drugs hypersensitivity
Autoimmune diseases
Cancer
Allergy

Investigations

The number of investigations will depend on the clinical circumstances.

On occasions, patients may need to be extensively investigated.

1. General:

Full Blood Count
Differential white blood cell count
Urinalysis with examination of the urinary sediment
Examination of any abnormal fluid collection

2. Microbiology:

Smears and culture of specimens from the throat, urethra, anus, cervix, and vagina (as indicated)
Sputum smears; culture
Blood culture
Urine microscopy, culture and sensitivity
Cerebrospinal fluid examination
Abnormal fluid collection: specimens for microscopy, culture and sensitivity testing

3. Chemistry:

Urine examination
Serum urea, electrolytes and creatinine
Blood glucose
Liver function tests
Cerebrospinal fluid examination

4. Radiology:

Chest radiograph

Other investigations as may be indicated in the clinical circumstances

Complications of fever

Untreated or poorly treated fever may result in any of the following complications:

Heat stroke in adults
Febrile convulsions in children
Complications associated with underlying cause(s) of fever

Treatment for fever

Objectives

To lower the temperature
To treat underlying causes
To improve patient’s quality of life

Non-drug treatment

Tepid sponging
Liberal oral sips of water (if clinical state is not a contraindication)

Drug treatment

1. Paracetamol

Adult:

500mg – 1 g orally every 4 – 6 hours; maximum 4 g daily

Child:

3 months – 1 year: 60-125 mg;

1-5 years: 120 – 250 mg;

6 – 12 years: 250-500 mg; repeated every 4-6 hours if necessary to a maximum of 4 doses in 24 hours

Infants under 3 months should not be given paracetamol unless advised by a doctor

2. Aspirin: (acetylsalicylic acid)