How to know if an infection has been caused by a virus or bacteria

At some point, you've probably sat across from a doctor who looked at your tired face and said, “It’s just a viral fever.” And if you're like most people, you've probably nodded and secretly wondered, ‘What exactly does that mean?’ How is it different from something bacterial? After all, the symptoms often feel the same: fever, sore throat, fatigue. Well, though some illnesses may share similar traits, a viral infection is different from one caused by bacteria. Let’s take a look at the difference between viral and bacterial infections, symptoms, and diagnostic methods to find them.

Both these infections are caused by microbes, which differ in structure, behaviour, and treatment. Bacterial infections are caused by bacteria, which are tiny microorganisms made up of a single cell. They can live independently in the body or the environment. Many bacteria are harmless or even helpful. However, some can cause diseases like strep throat, urinary tract infections, and tuberculosis. These infections are usually treated with antibiotics.

Viral infections, on the other hand, are caused by viruses, that are much smaller microorganisms compared to bacteria. Viruses are parasitic, which means they cannot survive or reproduce without a host cell. Viruses invade healthy cells and use them to multiply, often leading to illnesses such as the common cold, flu, COVID-19, and chickenpox. However, the worst part about viral infections is that they do not respond to antibiotics.

Both bacterial and viral infections share similar symptoms, so it could be difficult to distinguish between the two. However, some differences offer hints. For instance, viral infections often have a combination of symptoms such as cough, runny nose, sore throat, fatigue, and body aches, which usually come on gradually and improve within a week to 10 days.

Bacterial infections, on the otherhand, are more localised and intense. Bacterial infections often lead to a higher, more persistent fever and can worsen over time without treatment.

The doctor can diagnose based on physical exam, medical history, and symptoms. When symptoms alone aren’t conclusive, diagnostic tests are essential.

For instance, conditions such as measles or chickenpox can be diagnosed from a simple physical exam; however, fever, especially seasonal, amidst COVID-19 might require further examination. Samples of either blood, mucus, urine, or stool, among others, will be taken to determine the cause of your condition.

What sample to take really depends on your illness. A throat swab can detect Streptococcus bacteria in strep throat cases, while blood tests or cultures identify bacteria in UTIs or bloodstream infections. For respiratory infections, chest X-rays or sputum cultures may distinguish bacterial pneumonia from viral bronchitis. Advanced tools, like polymerase chain reaction (PCR) tests, can detect specific viral or bacterial DNA, and also provide high accuracy.

Treatment is based on the infection type. Viral infections typically resolve with rest, hydration, and over-the-counter symptom relief, because antibiotics are ineffective against viruses.

Bacterial infections, on the other hand, require antibiotics, but only when confirmed.

• Practice washing hands with soap and water.

• Keep your hands away from your face.

• Stay away from people who are sick and avoid others if you are sick.

• Personal hygiene.

• Follow food safety rules.

• Take precautions during the seasonal influenza season and also follow the guidelines provided by the authorities.