• Infectious Disease
• Your Family's Health

Bacteria or Virus: What’s Making You Sick?

We all get sick occasionally, from a cold, the flu, a sore throat, or a cough. We usually say we caught a “bug,” ask our doctor for a prescription to make us better, and expect the illness to go away within a reasonable amount of time.

Problem is, all “bugs” — or germs — aren’t the same, which means all infections aren’t the same, either. Bacterial and viral infections differ in a number of ways, and most importantly, require different treatments. 

Bacteria and viruses are similar in that they are both microbes — miniscule organisms that are so tiny they can only be seen through a microscope. And both can cause mild to serious illnesses. But that’s where the similarities end. Here’s a look at the differences between bacterial and viral infections, and why knowing the difference is important for your health.

Knowing whether your illness is caused by bacteria or a virus will tell your health care provider how to treat it.

What Are Bacterial Infections?

Bacteria are one-celled micro-organisms that can multiply quickly. Seen under a microscope, they look like rods, balls or spirals. 

Many bacteria are helpful, like the ones that help you digest food, help you fight disease and provide nutrients to your body. According to the National Institutes of Health (NIH), fewer than one percent of bacteria can actually make you sick.

Infectious bacteria (those that do make you sick) slip into your body and live among your healthy cells. Many emit chemicals called toxins, which can damage tissue. Streptococcus (strep), Staphylococcus (staph) and E. coli are some of the more commonly known bacteria that can cause infections.

Illnesses caused by infectious bacteria include:

• Strep throat
• Food poisoning
• Urinary tract infection
• Skin infections
• Toxic shock syndrome 

What Are Viral Infections?

Viruses are even smaller than bacteria. They consist of genetic material inside a protein-coated capsule. Viruses cannot survive on their own, so they invade your body’s cells in order to multiply. According to the NIH, this invasion can kill, damage or change your cells, and make you sick. 

Illnesses caused by viruses include:

• Colds
• Flu
• Most sore throats
• Most coughs and bronchitis (“chest colds”)
• Many sinus infections
• Many ear infections
• Chicken pox
• HIV/AIDS

Bacterial or Viral – How Do You Know?

For the most part, only your doctor can tell for sure whether your illness is bacterial or viral. Some diseases — like meningitis, pneumonia and diarrhea — can be caused by either. Don’t assume you know the cause of your illness until your doctor can verify it. Your doctor can sort through your symptoms, take a medical history, do a physical exam, and, if necessary, order tests to confirm the diagnosis and determine the cause. 

Knowing whether your illness is caused by bacteria or a virus will tell your health care provider how to treat it. Antibiotics are only effective against bacterial infections; they have no impact on viruses. Overusing or misusing antibiotics, including using them on viruses, can lead to resistance, in which bacteria adapt and no longer respond to antibiotic treatment. 

There are now antiviral medications on the market that can treat some viral infections. For most viruses, however, treatment consists of care to make the patient more comfortable and ease symptoms (like reducing fever).

Listen to Your Body

While most of us can weather a cold or a mild case of the flu without a doctor’s visit, call your health care provider if you have a high fever or other cause for concern. An accurate diagnosis will help you get the most effective treatment for whatever is ailing you.

Source: National Institutes of Health (MedlinePlus); Centers for Disease Control