What is the major cause for multiple sclerosis?!

What is the major cause for multiple sclerosis?

I have been told that a virus of some sort is to blame,is there any truth in that assumption?

This will give you an insight view of causes:

Causes

Your central nervous system contains millions of nerve cells that send their electrical signals to and from your brain along wire-like extensions of the cells called axons, or nerve fibers. Myelin is the fatty substance that coats and protects these fibers, similar to the way insulation shields electrical wires.

In people with multiple sclerosis, the immune system mistakenly destroys the cells that produce the myelin sheath. As a result, myelin becomes inflamed and swollen and detaches from the nerve fibers. The detached myelin may eventually be destroyed. Firm or hardened (sclerosed) patches of scar tissue form over the fibers. When nerve impulses reach a damaged area, some impulses are blocked or delayed from traveling to or from your brain. Ultimately, this process leads to degeneration of the nerves themselves, which likely accounts for the permanent disabilities that may develop in MS.

Doctors and researchers don't understand what causes this autoimmune reaction. Something seems to trigger the condition in susceptible people.

Genetic factors may make certain people more susceptible to multiple sclerosis. But genetic susceptibility is only part of the explanation. A number of researchers believe the disorder is related to a protein that mimics the myelin protein, which may be introduced into the body by a virus. Other researchers believe that the immune system overreacts toward myelin proteins in people with MS, which leads to an abnormal tendency to develop autoimmune disease.

A period of disease activity (exacerbation) may be triggered by a viral infection, such as a cold or flu, or by changes in the immune system during the first six months following a pregnancy.

Patterns of MS
Whatever the multiple sclerosis cause or trigger, the disease occurs in four main patterns:

* Relapsing remitting. This type of multiple sclerosis is characterized by clearly defined flare-ups, followed by periods of remission. The flare-ups typically appear suddenly, last a few weeks or months, and then gradually disappear. Most people with MS have this form at the time of diagnosis.
* Primary progressive. People with this less common form of multiple sclerosis experience a gradual decline, without periods of remission. People with this form of MS are usually older than 40 when signs or symptoms begin.
* Secondary progressive. More than half the people with relapsing remitting MS eventually enter a stage of continuous deterioration referred to as secondary progressive MS. Sudden relapses may occur, superimposed upon the continuous deterioration that characterizes this type of multiple sclerosis.
* Progressive relapsing. This is primary progressive MS with the addition of sudden episodes of new symptoms or worsened existing ones. This form is relatively uncommon.