Symptoms and Diagnosis How to Differentiate Between Viral Fever and Bacterial Fever

Fever refers to an increase in the body temperature when the body is dealing with an infection. It is the way the immune system screams that there is trouble; it can be at the cellular level or with an organ. However, no fever is the same. Knowing whether it is viral or bacterial is key to the management of the condition. When fever is mistaken for any other disease or treated wrongly, it may result in some consequences, particularly with a wrong prescription of antibiotics in treating viral diseases.

Symptoms of viral fever

Viral fevers are illnesses resulting from viruses, including but not limited to the flu virus, dengue fever virus or the cold virus. These fevers are usually moderate to within normal limits and commonly self-limiting. Here are the typical symptoms:

• Gradual onset: Viral fevers take time to develop, and this may take anything from one day to the next, depending on the specific virus.
• Low to moderate fever: In most cases, the temperature remains less than 102 °F (39 °C).
• Generalised symptoms: Same-day flu-like symptoms include body aches, fatigue, headache and chills.
• Upper respiratory symptoms: Headache, weakness and sleeplessness are also reported in persistent, steadfast viral fevers, often including cough, sore throat, stuffy nose and runny nose.
• Skin rashes: Certain viral fevers, including measles, chickenpox, etc., are characterised by rashes that are unique to them.
• Gastrointestinal symptoms: Vomiting, nausea or diarrhoea may be presented in severe viral infections.

Symptoms of bacterial fever

Bacteria infections tend to cause severe and specific symptoms compared to viral infections. Some of the distinguishing features include:

• Sudden onset: Bacterial fever usually has its onset in raised temperature.
• High fever: It is often above 102°F (39°C) and may often go for several days or weeks without being addressed.
• Localised symptoms: Like viral diseases, bacterial diseases are localised in certain parts of the body:
• Respiratory system: S. pneumoniae, a bacterial pneumonia, is likely to produce chest pain, productive cough and breathing difficulties.
• Urinary tract: UTIs cause dysuria, increased frequency and tenderness in the lower abdominal area.
• Skin and soft tissues: Redness, swelling and development of pus may indicate bacterial cellulitis or abscesses.
• Prolonged illness: As with other fevers, bacterial fevers can last longer than viral fevers if treated.
• Severe fatigue and weakness: Bacterial infections are always characterised by persistent and intense fatigue.

Key differences between viral and bacterial fevers

Onset:  

• Viral: Gradual
• Bacterial: Sudden

Severity of fever:

• Viral: Low to moderate
• Bacterial: High

Distribution of symptoms:

• Viral: Generalised  
• Bacterial: Localised  

Duration:  

• Viral: 3–7 days often self-limiting  
• Bacterial: Prolonged  

Diagnostic distinction between viral and bacterial fever

The division between viral and bacterial fevers is not always very clear and well-defined. Usually, physicians use a clinical approach by clinically assessing the patient and ordering tests in which the patient is suspected to have a particular disease.

• Medical history and physical examination: This was about reviewing symptoms, recent travels, exposures and physical findings to help define this.
• Complete blood count (CBC): High levels of white blood cells, particularly neutrophils, indicate bacterial infection as the body tries to fight it. An increase in the lymphocyte count is actually indicative of a viral infection.
• C-reactive protein (CRP) and procalcitonin tests: Higher concentrations of these enzymes are normally seen in bacterial infections.
• Blood, urine or sputum cultures: Bacterial cultures, in turn, help typecast the bacteria and know the type of antibiotic to use on them.
• Rapid diagnostic tests: An example of such tests that will provide quick results include the rapid strep test or flu antigen test.
• Imaging studies: Infections may require localisations with Chest X-rays or ultrasounds for infections in specific organs or CT scans.

Conclusion

The features of viral and bacterial fevers partially overlap, so how they are distinguishable can be crucial for treatment and stay complication-free. Recognising the patterns of the symptoms, going for regular check-ups and following the prescribed regimen are crucial. Be aware of your conditions to know the right time for you to seek help so that you receive the right treatment.