A virus is very small organism - smaller than a bacterium. It needs just one cell on the host to start replicating itself. Once the virus starts replicating itself and starts impacting the normal functioning of the cell and the overall body, it results in a viral infection.
A viral infection is contagious since the virus can always get transmitted from one infected person or other animals to humans. The virus that affect the respiratory system and the upper body can easily get transferred through coughing or sneezing or by coming in touch with an infected person. Other virus types, like the AIDS virus, can transmit only through sexual contact or blood transfusions or using infected syringes.
A common of trait of virus is mutation. When virus replicates, the new strain of virus may genetically alter itself thereby becoming immune to any existing anti viral medicines or vaccines. This is the biggest threat from a viral infection. In April 2009, the H1N1 virus that seemed to have originated from Mexico spread all around the world causing concerns of a pandemic since the strain of this virus was never known before and there were no medicines or vaccines to fight or prevent this virus from spreading. Fortunately, it did not turn out to be any more harmful than the common influenza virus for which there is a vaccine available. The scientists are very busy in developing the vaccine for this virus before the next flu season, just in case it turns out to be more resistive to the existing drugs.
A virus needs a host to replicate. It cannot survive outside the host for more than 4-7 days. Some viruses die within minutes if they are not in side a cell of a host's body. Therefore if door knobs, faucets and other common surfaces in a home with an infected person are disinfected with a soap based cleaner, the virus can be prevented from spreading. If an infected person is kept in isolation and the people attending to the sick observe common procedures to avoid coming in touch with the virus, the spread of a viral infection can be controlled very effectively.
Upper Body Infections:
We have all experienced cold. It is one of the most common viral infections that spreads around easily and fortunately is the one that the body can get rid of very easily. No medication is necessary to cure common cold. As a matter of fact, medicines that prevent runny nose or temperature associated with cold, normally make the healing process only longer because conditions like the runny or stuffed nose and higher temperature are a way of the body to fight the virus. Suppressing these symptoms only helps the virus to survive longer.
A sore throat infection might also be a viral infection and gets cured easily. A viral infection of the throat is different from a bacterial infection of the throat. A viral infection is normally associated with cold like symptoms whereas a strep throat infection causes only the sore throat and discomfort and in the throat.
Influenza A or flu as it is more commonly called, is a viral infection that is contracted by millions of people around and the world and thousands die because of it. It can be easily prevented by taking an annual flu vaccine.
Influenza should be treated to avoid very high body temperature. Sometimes, fever that accompanies influenza may be as high as 106F. Other symptoms of influenza include body aches, headache, runny nose and sore throat.
Bronchitis is the inflammation of the air passages inside the lungs. The inflammation causes the cells in the bronchi or airways to release fluids to fight the infection. Acute bronchitis may also be accompanied with fever.
The body's reflex action causes coughing to try to throw out the fluid out of the airways. Wheezing or asthma like symptoms of being short of breath might occur due to the congestion caused by the fluids in the bronchi. If the patient has difficulty breathing or throws out blood with cough, one should seek medical attention as soon as possible. The coughing can become severe and last several weeks. If the cough lasts for more than a week, one should see medical attention to ensure it is not pneumonia.
People who are exposed to excess pollution also contract bronchitis because the fumes and dust particles irritate the lings.
A viral bronchitis is different from a bacterial bronchitis which is a form of pneumonia.
The viral bronchitis can normally be treated by using off the shelf cough suppressant and fever medications and by drinking lot of fluids.
A bacterial bronchitis is cured using antibiotics that can be prescribed only by a medical practitioner.
Since the patient may not be able to determine if it is a viral or a bacterial bronchitis, it is best to see a doctor if the bronchitis symptoms last more than a week.
Nervous system infections:
The viral infections of the central nervous system that includes the brain and the spinal cord can cause meningitis and encephalitis. Meninges are the tissues covering the spinal cord and the brain. Nervous system infections are very acute and devastating in nature.
Meningitis and encephalitis are of many types and many of them are mild in nature and can be treated. Herpes infection is considered to be more severe. Even if the patient survives, a herpes infection may leave harm on the overall immune and nervous systems of the body.
Measles, chicken pox and rubella are common skin infections that affect the skin. These days almost everyone, at least in the developed countries, is vaccinated against these infections.
Molluscum contagiosum, a skin infection, causes boils like tiny bumps on the skin. The bumps can remain on the skin for 2 to 3 years and get cured all by themselves. Doctors can prescribe some creams or other treatments to help.
HIV (Human Immunodeficiency Virus) Infection:
HIV infection is contagious and is commonly transmitted from one person to another by having sex with an infected person, by coming in contact with an infected blood like through the use of syringes and needles that have been used on an infected person, and lastly from infected women to their new born babies.
Presence of HIV may not become apparent for up to 10 years. However, an infected person, even without having any symptoms, can transmit the virus to another person. When a person contract HIV, one may develop a brief flu like symptoms for two to four weeks.
When the HIV virus spreads and makes the immune system of the body too weak to fight any other infections, the disease is then called AIDS (Acquired Immunodeficiency Syndrome). AIDS is the name given to the later stages of HIV infection.