Fever in Emergency Care: Assessment, Differential Diagnosis and Management

1. Learning objectives

• Define fever, hyperpyrexia and hyperthermia and explain why they are different.
• Take a structured fever history, including travel, malaria, VHF, drug and occupational exposures.
• Recognise sepsis, shock, meningitis, severe malaria and other time-critical causes.
• Perform a safe ABCDE assessment and select focused tests without delaying resuscitation.
• Describe pre-hospital, emergency-department, pharmacological and nursing management.
• Adjust assessment for infants, pregnancy, older adults and immunocompromised patients.
• Give discharge advice, prevention counselling and a clear safety-net plan.

2. Definitions and physiology

Fever (pyrexia) is a regulated rise in the hypothalamic set-point, usually during infection or inflammation. The patient may feel cold and shiver while the set-point is rising. Hyperthermia is an uncontrolled temperature rise from excess heat production, impaired heat loss or drugs; the set-point is not reset. Heat stroke, serotonin syndrome, neuroleptic malignant syndrome and malignant hyperthermia are hyperthermic emergencies. Hyperpyrexia refers to an exceptionally high fever and requires urgent assessment, but the exact threshold and method depend on the guideline and measurement site.

Fever can improve host immune function, but excessive metabolic demand, dehydration, delirium, seizures or cardiorespiratory stress may make it dangerous. Treat the underlying cause and the patient’s physiological compromise, not the number alone.

3. Causes of fever in emergency practice

4. Triage: who needs immediate resuscitation?

At triage, record temperature using a validated device and method, but prioritise airway, breathing, circulation, disability and exposure. Use an early warning score if available and do not allow a waiting-room queue to delay unstable patients.

4.1 High-risk groups

• Neonates and young infants, especially those under 3 months.
• Children with malnutrition, sickle-cell disease or incomplete immunisation.
• Pregnant or recently postpartum patients.
• Older adults who may have delirium, hypothermia or few localising symptoms.
• People living with HIV, on chemotherapy, transplant medicines, long-term steroids or other immunosuppression.
• Patients with diabetes, renal disease, heart failure, chronic lung disease or severe anaemia.
• Recent travellers, healthcare workers, laboratory staff, animal handlers and contacts of outbreak cases.

5. Initial contact and infection prevention

1. Perform hand hygiene and offer a mask to a coughing patient if tolerated.
2. Screen for cough, diarrhoea, vomiting, rash, bleeding, travel, outbreak contact and VHF risk before placing the patient in a crowded area.
3. Separate patients with respiratory symptoms or a credible VHF exposure while maintaining dignity and confidentiality.
4. Use standard precautions and add droplet, contact, airborne or high-level VHF precautions according to the suspected syndrome and local policy.
5. Use gloves and eye protection for blood, vomit, diarrhoea, suction or other splash risk; do not use gloves as a substitute for hand hygiene.

6. Fever history: the questions that change management

6.1 Chronology and temperature

• When did fever begin? Was onset sudden or gradual?
• What was the highest measured temperature, at which site and with which device?
• Is the fever continuous, intermittent, periodic or associated with rigors or night sweats?
• Has the patient taken paracetamol, NSAIDs, antibiotics, antimalarials, steroids or traditional medicines?

6.2 Localising symptoms and exposure

• Headache, photophobia, neck stiffness, confusion, seizures or weakness.
• Cough, sore throat, pleuritic pain, breathlessness or sputum.
• Abdominal pain, diarrhoea, vomiting, jaundice or urinary symptoms.
• Rash, wound, skin infection, joint pain, muscle pain or bleeding.
• Malaria prevention, recent mosquito bites, travel, sick contacts, sexual history and vaccination status.
• Animal, tick, rodent, cave, occupational, healthcare, funeral or body-fluid exposure.
• Pregnancy possibility, last menstrual period, breastfeeding and recent delivery.

7. Examination: ABCDE plus a fever-focused survey

A – Airway

• Check speech, secretions, vomiting, facial swelling, stridor and ability to protect the airway. Prepare suction and a senior airway plan for reduced consciousness.

B – Breathing

• Count rate, effort and pattern; check SpO₂, chest signs, cyanosis and fatigue. Consider pneumonia, pulmonary oedema, metabolic acidosis and severe anaemia.

C – Circulation

• Measure pulse, blood pressure, capillary refill, skin temperature and urine output. Look for dehydration, bleeding, mottling, jaundice and signs of septic or hypovolaemic shock.
• Use weight or a paediatric length-based method for fluid and drug calculations; never guess a child’s dose.

D – Disability

• Assess AVPU/GCS, pupils, seizures and glucose. Delirium may be the first sign of sepsis in an older adult.

E – Exposure

• Inspect skin, rash, petechiae, purpura, wounds, joints, meningism, injection sites and hydration while preserving warmth and dignity.

8. Pattern recognition and differential diagnosis

9. Investigations and interpretation

10. Immediate and pre-hospital care

1. Move the unstable patient to a resuscitation area; do not delay for a complete history.
2. Position for airway and perfusion; use recovery position if unconscious and breathing with no contraindication.
3. Give oxygen for hypoxaemia or respiratory distress and monitor response.
4. Check glucose, treat hypoglycaemia under protocol and reassess consciousness.
5. For dehydration or shock, use oral rehydration if alert and able to drink; use isotonic IV fluid cautiously with frequent perfusion and lung reassessment.
6. Use paracetamol/acetaminophen within local dose limits for distressing fever; avoid aspirin/NSAIDs when bleeding, renal injury or dengue/VHF is possible.
7. Do not give antibiotics or antimalarials blindly when a trained diagnostic pathway is available, but never delay time-critical treatment in a patient meeting severe-malaria or sepsis criteria.
8. Call the receiving facility, state the suspected syndrome and transmit serial observations, treatments and exposure risks.

11. Hospital management of fever

11.1 Treat the physiology first

• Use an early warning score, sepsis screen or paediatric emergency triage tool where available.
• Repeat ABCDE after every intervention and document time, dose, route and response.
• Provide oxygen, airway support, cautious fluid resuscitation and vasopressors in critical care when indicated.
• Measure urine output and consider catheterisation only when essential and safe.
• Control seizures, hypoglycaemia, severe pain and agitation while investigating the cause.

11.2 Sepsis pathway

1. Recognise suspected infection plus organ dysfunction or deterioration; fever is not required.
2. Obtain cultures and lactate/other tests when this can be done safely without delaying treatment.
3. Give empiric antimicrobials according to local formulary and likely source, ideally promptly in shock or high-risk sepsis.
4. Give crystalloid for hypoperfusion with repeated assessment of blood pressure, capillary refill, lung sounds, mental status and urine output.
5. Escalate to senior/critical-care care for persistent hypotension, rising lactate, increasing oxygen requirement or organ failure.

11.3 Malaria pathway in Uganda

• Ask about residence/travel, prophylaxis, prior malaria, pregnancy and antimalarial use.
• Use an RDT or microscopy promptly where feasible. WHO recommends testing suspected malaria before treatment.
• Severe malaria features include impaired consciousness, repeated seizures, respiratory distress, shock, severe anaemia, hypoglycaemia, acidosis, jaundice with other severe features, haemoglobinuria, acute kidney injury or inability to drink.
• Severe malaria is a hospital emergency: activate the local parenteral artesunate and referral protocol, manage glucose and airway, and monitor for post-treatment haemolysis and other complications.
• Uncomplicated malaria should receive the nationally recommended oral antimalarial with adherence counselling; do not use leftover or incomplete courses.

12. Fever in children, pregnancy and older adults

Children and infants

• Measure temperature accurately and assess feeding, breathing, interaction, capillary refill, urine, rash, seizures and immunisation.
• Any young infant with fever, hypothermia, poor feeding, lethargy, fast breathing, apnoea or abnormal colour requires urgent assessment.
• Use weight-based or length-based medication and fluid calculations; avoid aspirin in children.
• Do not force oral fluids in a drowsy or vomiting child who cannot protect the airway.

Pregnancy and postpartum

• Ask about gestation, fetal movement, rupture of membranes, urinary symptoms, malaria risk, breast symptoms and postpartum wounds.
• Assess maternal ABCDE first while considering fetal assessment and obstetric referral.
• Use pregnancy-safe medicines and antimicrobials according to Uganda guidelines; avoid self-medication and tetracycline/other contraindicated drugs unless specifically directed.

Older or immunocompromised patients

• Fever may be absent; look for confusion, falls, weakness, tachypnoea, hypotension, reduced intake or functional decline.
• Review corticosteroids, chemotherapy, transplant medicines and recent hospitalisations.
• Have a lower threshold for cultures, observation, admission and senior review.

13. Pharmacological principles

14. Nursing interventions and monitoring

• Record temperature, pulse, respirations, blood pressure, SpO₂, pain, AVPU/GCS and urine output at the required frequency.
• Trend rather than merely record: a rising respiratory rate or falling alertness may precede hypotension.
• Maintain fluid balance, monitor stool/vomit losses and inspect IV sites.
• Provide tepid comfort measures, light clothing, ventilation and hydration; avoid ice baths or aggressive cooling in routine fever.
• Administer medicines safely, check allergies, observe response and document adverse effects.
• Use infection-control precautions, safe specimen handling and environmental cleaning.
• Prevent pressure injury, falls, delirium and aspiration in weak or confused patients.
• Explain the diagnosis uncertainty, testing plan, red flags and family communication pathway.

15. Discharge, admission and safety net

Discharge is appropriate only when the patient is clinically stable, can drink or has a reliable plan, serious causes have been considered, follow-up is available and the responsible clinician agrees.

• Give written instructions for dose, timing and maximum daily antipyretic amount.
• Explain return immediately for confusion, difficulty breathing, persistent vomiting, severe headache/neck stiffness, seizure, bleeding, jaundice, inability to drink, reduced urine, worsening weakness or fever that persists/returns.
• Use mosquito prevention, hand hygiene, respiratory etiquette, safe food/water and vaccination advice where appropriate.
• Advise against leftover antibiotics, incomplete antimalarial courses, aspirin/NSAIDs when contraindicated and unregulated injections.
• Arrange review for malaria, pregnancy, infants, immunocompromise, recurrent fever, abnormal tests or unresolved diagnostic uncertainty.

16. Clinical scenarios

17. Common mistakes

• Treating the temperature while ignoring shock, hypoxia or altered consciousness.
• Assuming every fever is malaria without testing or considering sepsis and VHF.
• Using a single normal temperature or blood pressure to declare a patient safe.
• Giving incorrect paediatric doses because weight was guessed.
• Using antibiotics without a source, review plan or attention to local resistance.
• Overcooling, ice bathing or withholding fluids from a stable patient who can drink.
• Missing pregnancy, immunosuppression, sickle-cell disease or recent hospital exposure.
• Discharging without return precautions, follow-up and documented patient understanding.

18. Quick revision questions

1. Differentiate fever, hyperthermia and hyperpyrexia.
2. List eight red flags in a febrile patient.
3. Why can sepsis exist without a high temperature?
4. What exposure questions raise concern for VHF?
5. When should a febrile patient be moved to resuscitation rather than a routine queue?
6. What does WHO recommend about malaria testing before treatment?
7. List severe-malaria features that require urgent hospital care.
8. How do you modify fever assessment for infants, pregnancy and older adults?
9. What should be documented after antipyretic, fluid or antimicrobial treatment?
10. Give six discharge safety-net instructions.

19. Key takeaways

References and further reading

• WHO: Sepsis fact sheet
• WHO: Malaria diagnostic testing
• WHO: Malaria treatment
• Uganda Clinical Guidelines 2023
• CDC: Caring for patients with sepsis
• WHO: Dengue and severe dengue
• CDC: Screening for viral haemorrhagic fevers