Viral diseases: Introduction
A viral infection is any type of illness or disease caused by a virus, a type of microbe. Microbes are tiny organisms that cannot be seen without a microscope and include bacteria, fungi, and some parasites, as well as viruses.
A viral infection occurs when a virus enters the body through such processes as breathing air contaminated with a virus, eating contaminated food, or by having sexual contact with a person who is infected with a virus. A viral infection may also be caused by an insect bite. In a viral infection, the virus invades the inside of the body's cells in order to reproduce. A virus then spreads to other cells and repeats the process.
This process of viral infection results in a variety of symptoms that vary in character and severity depending on the type of viral infection and individual factors. Common symptoms of a viral infection include fatigue, flu-like symptoms and fever. For more information on symptoms, refer to symptoms of viral infection.
Many types of viral infections, such as a cold, are self limiting in generally healthy people. This means that the viral infection causes illness for period of time, then it resolves and symptoms disappear. However, some people are at risk for developing serious complications of viral infection. In addition, certain types of viral infections, such as HIV/AIDS, are not self limiting and cause serious complications and are eventually fatal. For more information on complications and symptoms, refer to symptoms of viral infection.
There are many types of viruses that cause a wide variety of viral infections or viral diseases. For example, there are over 200 different viruses that can cause a cold or an upper respiratory infection. Other common viruses include the influenza virus, which causes influenza or the flu. The Epstein-Barr virus and the cytomegalovirus cause infectious mononucleosis. The varicella zoster virus causes shingles, and chickenpox, and HIV causes AIDS.
Making a diagnosis of a viral infection begins with taking a thorough personal and family medical history, including symptoms, and completing a physical examination. Diagnosing some viral infections, such as seasonal influenza, may be made based on a history and physical.
Blood tests, such as a complete blood count (CBC) may be done. A complete blood count measures the numbers of different types of blood cells, including white blood cells (WBCs). Different types of WBCs increase in number in characteristic ways during an infectious process, such as viral infection.
A culture test may also be performed. This test requires taking a small sample from the body area that is suspected to be infected with a virus and grows the sample in a lab to determine the type of microorganism causing illness. Common samples tested with a culture include those from the throat, blood, and sputum from the lungs.
Diagnostic tests may also include a lumbar puncture, also called a spinal tap, which involves withdrawing a small sample of cerebrospinal fluid (CSF) from the spine with a needle. The sample of CSF is tested for white blood cells and other indications of viral infection that may be in the spine or brain, such as viral meningitis.
X-rays may be performed to assist in the diagnosis of some viral infections. This may include taking a chest X-ray for suspected cases of viral pneumonia. Additional tests may be performed in order to rule out or confirm other diseases that may accompany viral infection or cause similar symptoms, such as a secondary bacterial infection.
It is possible that a diagnosis of viral infection can be missed or delayed because some symptoms, such as fever, headache, nausea and vomiting, are similar to symptoms of other diseases. For more information on misdiagnosis, refer to misdiagnosis of viral infection.
Viral infections are not curable with antibiotics. For more information on treatment, refer to treatment of viral infection. ...more »
Viruses are a very common type of infectious disease. Many of the most common human diseases are viral. There are literally hundreds of types of viral conditions.
Viruses are the smallest life-form existing, since they are not even a single cell.
It is almost like they are not alive at all.
They are small strands of DNA-like cell material.
A virus consists mostly of RNA and cannot survive without host cells. ...more »
Viral diseases: Symptoms
Symptoms of viral infection vary depending on the type of viral infection, the area of the body that is infected, the age and health history of the patient and other factors. The symptoms of viral infection can also resemble symptoms of other diseases, such as bacterial infections.
Symptoms may affect almost any area of the body or body system and include fever ...more symptoms »
Viral diseases: Treatments
The first step in treating viral infection is preventing its occurrence and spread. Vaccines are available to prevent some common viral infections, such as chickenpox, shingles, influenza, HPV, hepatitis B, hepatitis A, measles and mumps.
Prevention of the spread of harmful viruses that cause viral infection also includes frequent hand ...more treatments »
Viral diseases: Misdiagnosis
A diagnosis of viral infection may be delayed because some symptoms are vague, nonspecific, or may initially be mild. These include body aches, weight loss, fatigue, or irritability. Other symptoms, such as headache, may initially be assumed to be related to another condition, such as migraine headache. In addition, viral pneumonia or viral meningitis may be ...more misdiagnosis »
Symptoms of Viral diseases
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Treatments for Viral diseases
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treatments for Viral diseases
Wrongly Diagnosed with Viral diseases?
Viral diseases: Related Patient Stories
Viral diseases: Deaths
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Alternative Treatments for Viral diseases
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Types of Viral diseases
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Types of Viral diseases
Causes of Viral diseases
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Prevention of Viral diseases
Prevention information for Viral diseases has been compiled from various data sources
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None of these methods guarantee prevention of Viral diseases.
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Article Excerpts about Viral diseases
Viruses are among the smallest microbes, much smaller even
than bacteria. Viruses are not cells. They consist of one or more
molecules of DNA or
RNA, which contain the virus's genes
surrounded by a protein coat. Viruses can be rod-shaped, sphere-shaped, or
multisided. Some look like tadpoles.
(Source: excerpt from Microbes in Sickness and in Health -- Publications, National Institute of Allergy and Infectious Diseases: NIAID)
Definitions of Viral diseases:
Any disease caused by a virus.
- (Source - Diseases Database)
Infection by a virus that is pathogenic to humans
- (Source - WordNet 2.1)
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