Viral Illness vs. Bacterial Infection

Difference Between Viral and Bacterial Infections

Bacteria are tiny living organisms that exist throughout the world. They are present in the home, on the skin, everywhere. Probiotics for example are bacteria that live in our intestines all the time and help with digestion. Other bacteria such as strep cause illness in people and require antibiotics to help the body’s immune system fight them off.

Viruses are even tinier organisms that are also everywhere. Some of them can cause illnesses with as much fever and discomfort as bacterial infections. Unlike with bacteria, antibiotics are not effective against viruses. The body’s immune system has to fight viruses off on its own, and usually they resolve with little more than rest, fluids and patience.

Viral illnesses are very contagious (usually more contagious than bacterial infections) and many times they are passed around from family member to family member, or from child to child at the daycare, school or in other social settings.

Because they are more common, viral infections will account for most of your child’s illnesses. Your doctor or nurse practitioner will recommend measures to help alleviate some of the symptoms (e.g. sore throat, vomiting, diarrhea, runny nose, cough and congestion) associated with your child’s viral illness.

Occasionally a child with a viral illness will be more susceptible to catching a bacterial infection such as an ear infection, pneumonia, or sinus infection, and will then need to be treated with an antibiotic to kill the bacteria while the body fights off the virus. We can only determine if a concurrent bacterial infection is present if we examine your child.

We do not treat infections with antibiotics unless we have good evidence that bacteria are the cause. One reason for this is that overuse of antibiotics leads to antibiotic resistance, and then the antibiotics won’t work when we need them to. A second reason is that antibiotics can cause side effects such as diarrhea, and we don’t want to put children at risk for side effects if there’s no benefit to using the antibiotic (i.e. in viral illnesses).

Demystifying “It’s Just a Virus”