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    Bacterial and Viral Infections

    The Differences Between Bacteria and Viruses continued...

    Viruses are tinier: the largest of them are smaller than the smallest bacteria. All they have is a protein coat and a core of genetic material, either RNA or DNA. Unlike bacteria, viruses can't survive without a host. They can only reproduce by attaching themselves to cells. In most cases, they reprogram the cells to make new viruses until the cells burst and die. In other cases, they turn normal cells into malignant or cancerous cells.

    Also unlike bacteria, most viruses do cause disease, and they're quite specific about the cells they attack. For example, certain viruses attack cells in the liver, respiratory system, or blood. In some cases, viruses target bacteria.

    Diagnosis of Bacterial and Viral Infections

    You should consult your doctor if you think you have a bacterial or viral infection. Exceptions include the common cold, which is usually not life-threatening.

    In some cases, it's difficult to determine the origin of an infection because many ailments -- including pneumonia, meningitis, and diarrhea -- can be caused by either bacteria or viruses. But your doctor often can pinpoint the cause by listening to your medical history and doing a physical exam.

    If necessary, he or she also can order a blood or urine test to help confirm a diagnosis, or a "culture test" of tissue to identify bacteria or viruses. Occasionally, a biopsy of affected tissue may be required.

    Treatment of Bacterial and Viral Infections

    The discovery of antibiotics for bacterial infections is considered one of the most important breakthroughs in medical history. Unfortunately, bacteria are very adaptable, and the overuse of antibiotics has made many of them resistant to antibiotics. This has created serious problems, especially in hospital settings.

    Antibiotics are not effective against viruses, and many leading organizations now recommend against using antibiotics unless there is clear evidence of a bacterial infection.

    Since the beginning of the 20th century, vaccines have been developed. Vaccines have drastically reduced the number of new cases of viral diseases such as polio, measles, and chickenpox. In addition, vaccines can prevent such infections such as the flu, hepatitis A, hepatitis B, human papillomavirus (HPV), and others.

    But the treatment of viral infections has proved more challenging, primarily because viruses are relatively tiny and reproduce inside cells. For some viral diseases, such as herpes simplex virus infections, HIV/AIDS, and influenza, antiviral medications have become available. But the use of antiviral medications has been associated with the development of drug-resistant microbes.

    WebMD Medical Reference

    Reviewed by Melinda Ratini, DO, MS on April 10, 2015
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