Fever is a common symptom in children and can be caused by both viral and bacterial infections. Understanding the difference between the two is crucial for ensuring the correct treatment, especially to avoid the unnecessary use of antibiotics, which are ineffective against viral infections and contribute to antibiotic resistance.
This guide is designed to help healthcare professionals and parents differentiate between viral and bacterial fevers using clinical history, examination findings, and the Centor Scoring System, particularly useful for diagnosing bacterial pharyngitis. The goal is to minimise inappropriate antibiotic use and ensure accurate diagnosis and treatment.
Why It’s Important to Distinguish Between Viral and Bacterial Fevers
– Antibiotics are ineffective for viral infections: Most viral infections resolve on their own, and the unnecessary use of antibiotics can lead to side effects and contribute to antibiotic resistance.
– Accurate diagnosis leads to appropriate treatment: Timely identification of bacterial infections ensures prompt antibiotic treatment, reducing the risk of complications.
– Reducing anxiety in parents: Educating parents about the difference helps to alleviate anxiety and promotes understanding about why antibiotics are not always necessary.
Viral vs. Bacterial Fever: Key Differences
1. Viral Fever
Viral fevers are caused by infections such as the common cold (rhinovirus), influenza, or respiratory syncytial virus (RSV).
– Duration: Viral fevers typically last 3 to 5 days and resolve without specific treatment.
– Common Symptoms: Runny nose, cough, sore throat, and body aches are often present. Fevers are generally mild to moderate, peaking in the evenings.
2. Bacterial Fever
Bacterial fevers result from infections such as strep throat (streptococcal infection), urinary tract infections (UTIs), or bacterial pneumonia.
– Duration: Bacterial fevers often persist and do not resolve without antibiotic treatment.
– Common Symptoms: High, persistent fever, frequently exceeding 39°C (102°F), often accompanied by specific symptoms like severe throat pain, earache, or abdominal pain.
Clinical History: Key Factors for Differentiating Viral vs. Bacterial Fevers
Viral Infections
– Onset: Symptoms develop gradually, starting with mild fever and progressing to cold-like symptoms.
– Pattern: Fever fluctuates throughout the day and is typically low to moderate in intensity.
– Associated Symptoms: Cold symptoms such as sneezing, nasal congestion, watery eyes, and general body aches are common.
Bacterial Infections
– Onset: Bacterial infections often present with an abrupt onset of high fever and significant localised pain (e.g. sore throat or ear pain).
– Pattern: The fever is typically high and sustained, with the child appearing ill throughout the day.
– Associated Symptoms: More severe, localised symptoms, such as swollen lymph nodes, pus in the throat, or abdominal pain, may be present.
Clinical Examination: Identifying Viral and Bacterial Fevers
A thorough physical examination can provide vital clues for distinguishing between viral and bacterial infections.
General Appearance
– Viral Fever: The child may appear well between fever episodes and remain fairly active.
– Bacterial Fever: Children with bacterial infections are more likely to appear lethargic, irritable, or acutely unwell.
Throat Examination
– Viral Infection: Mild redness without pus or exudate is usually observed.
– Bacterial Infection: The tonsils may be swollen with white or yellow exudate, particularly in cases of streptococcal pharyngitis.
Ear Examination
– Viral Otitis Media: The eardrum may appear mildly red with minimal swelling.
– Bacterial Otitis Media: The eardrum is often bulging, with pus behind the tympanic membrane.
Lung Examination
– Viral Infection: Diffuse wheezing or rhonchi may be heard throughout both lungs.
– Bacterial Infection: Localised crackles or decreased breath sounds are typical of bacterial pneumonia.
Centor Scoring System: Diagnosing Bacterial Pharyngitis
The Centor Scoring System is a valuable tool to assess the likelihood of streptococcal pharyngitis (strep throat), a common bacterial cause of fever in children. It helps guide decisions about the need for antibiotics based on clinical features.
Centor Criteria (1 point for each):
1. Tonsillar Exudate: White or yellow pus on the tonsils.
2. Tender Anterior Cervical Lymph Nodes: Swelling and tenderness in the front of the neck.
3. Fever: Temperature above 38°C (100.4°F).
4. Absence of Cough: The absence of a cough is a sign of bacterial infection.
Scoring:
– 0-1 Points: Low likelihood of bacterial infection. Antibiotics are not recommended; likely viral.
– 2-3 Points: Moderate risk of strep throat. Consider a rapid antigen test or throat culture before prescribing antibiotics.
– 4-5 Points: High likelihood of strep throat. Empirical antibiotic therapy or confirmatory testing is appropriate.
Application in Paediatrics: The Centor score is most useful in children over 3 years old. In younger children, bacterial pharyngitis is less common, so clinical judgement is essential.
Investigations: Diagnostic Tools
If clinical history and examination are inconclusive, investigations can assist in determining the cause of fever.
– Blood Tests:
– Viral Infection: Normal or mildly elevated white blood cell (WBC) count, with a predominance of lymphocytes.
– Bacterial Infection: Elevated WBC count, particularly with an increase in neutrophils.
– C-Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR): Raised levels suggest bacterial infection, although they may also increase in severe viral infections.
– Procalcitonin: Elevated levels are more specific to bacterial infections and can help in differentiation.
– Throat Swab or Rapid Strep Test: These are essential if streptococcal pharyngitis is suspected.
– Urine Test: Urine dipstick or culture can help diagnose bacterial infections, such as UTIs.
Management Guidelines: Viral vs. Bacterial Fevers
Viral Infections
– No Antibiotics Required: Most viral infections resolve with supportive care, including hydration, rest, and fever-reducing medications like paracetamol or ibuprofen.
– Monitor Symptoms: If the fever lasts beyond 5 days or worsens, re-evaluation may be necessary to rule out a secondary bacterial infection.
Bacterial Infections
– Antibiotics Required: Once a bacterial infection is confirmed, antibiotics are needed for recovery.
– Common Antibiotics:
– Strep Throat: Amoxicillin or penicillin is typically prescribed.
– Pneumonia or UTIs: Antibiotics are chosen based on the specific bacterial cause.
Key Points for Parents and Healthcare Professionals
– Most Fevers are Viral: Viral infections are self-limiting, typically resolving in 3–5 days with supportive care. Antibiotics are not necessary and may cause harm if used improperly.
– Centor Scoring System: This system is helpful for distinguishing between viral and bacterial causes of sore throats, reducing unnecessary antibiotic use.
– Consult a Doctor: If in doubt, especially with young children or those with underlying health conditions, consult a healthcare professional for a proper diagnosis and treatment plan.
Reducing Antibiotic Overuse
Unnecessary use of antibiotics for viral infections contributes to the growing problem of antibiotic resistance. Educating both parents and healthcare professionals about the differences between viral and bacterial infections is key to addressing this issue and ensuring appropriate treatment.
