Virus or Bacteria

Bacteria are microscopic, single-celled organisms. There are thousands of different kinds, and they live in every conceivable environment all over the world. They live in soil, seawater, and deep within the earth’s crust. Some bacteria have even been reported to live in radioactive waste. Many bacteria live in the bodies of people and animals—on the skin and in the airways, mouth, and digestive, reproductive, and urinary tracts—without causing any harm. Such bacteria are called resident flora, or the microbiome. Many resident flora are actually helpful to people—for example, by helping them digest food or by preventing the growth of other, more dangerous bacteria. Only a few kinds of bacteria cause disease. They are called pathogens. Sometimes bacteria that normally reside harmlessly in the body cause disease. Bacteria can cause disease by producing harmful substances (toxins), invading tissues, or doing both.

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The symptoms of a viral infection and bacterial infection can be similar. They can each cause symptoms such as fever, coughing, vomiting, diarrhea, fatigue, and cramping. Bacteria and viruses are both microbes, but they are different types of organisms that cause diseases in different ways. Viruses are not complete cells—they need a living host, such as a person, animal, or plant, to survive. Much smaller than bacteria, viruses invade cells inside a host to reproduce. Most viruses will cause illness. Bacteria, on the other hand, are usually single-celled organisms that can survive on their own. Most bacteria are harmless, and some types are beneficial, such as the bacteria in the gut that help us digest food. Other strains of bacteria can cause serious illness.

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Viral illnesses are contagious and can be transmitted through coughs, sneezes, and other bodily fluids. The common cold, flu (influenza), chicken pox, measles, AIDS, hepatitis A & B, rabies, and shingles are examples of viral infections. Viral infections are generally more difficult to treat than bacterial infections because the virus "hides" inside normal, living cells, protecting them from treatment with antibiotics.

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Bacterial infections occur when harmful bacteria enter the body. Often this happens because the organism takes advantage of a situation, such as a break in the skin or a compromised immune system. This is called an “opportunistic” infection. A bacterial infection usually stays within one area of the body, meaning it is a localized infection. A sinus infection displays localized symptoms of a bacterial infection including congestion, sinus pressure, and thick, greenish-yellowish nasal discharge. Some bacterial infections are contagious, but many common bacterial infections are not. These include ear, sinus, bladder, or kidney infections.

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Treatment of viral and bacterial infections differs. Viral infections generally must run their course, with treatment aimed at easing symptoms and providing relief. Sometimes, antiviral medications are prescribed for specific infections, such as flu (influenza) and shingles. Bacterial infections can be treated with antibiotics. Antibiotics either kill bacteria or interrupt their ability to multiply. It is important to only take antibiotics for bacterial infections and to follow a healthcare provider’s instructions carefully. Vaccines may also be used to prevent bacterial infections. Vaccines have been developed for bacterial infections including diphtheria, tetanus, whooping cough, meningococcal meningitis, pneumococcal pneumonia, and typhoid fever.