HARVARD RESEARCHERS MAY HAVE discovered the cause of multiple sclerosis (MS). This progressive disease affects 2.8 million individuals worldwide, and there is no cure.

In the United States, a study funded by the National Multiple Sclerosis Society confirms that nearly one million people live with MS, more than twice the original estimate from a previous study.

Now comes news from Harvard researchers that points to the condition’s cause. Today, we look at multiple sclerosis, including epidemiology, risk factors, symptoms, and disease course.

We’ll end with the good news — researchers appear to have identified a viral cause of the disease. Spoiler alert: It’s the so-called kissing virus, or Epstein-Barr virus, the pathogen that causes mono.

What is multiple sclerosis?

Multiple sclerosis is a chronic disease that can affect your brain, spinal cord, and the optic nerves in your eyes. It can also be associated with other essential body functions such as muscle control and balance.

The symptoms associated with MS are variable. Some with the disease have mild symptoms and need no treatment. Others have challenges moving around and doing the typical tasks of daily living.

Multiple sclerosis results from the immune system attacking a fatty material (myelin) that envelopes nerve fibers to protect them. When the outer shell is lost, your nerves are more likely to become damaged, and scan tissue can form.

With nerve damage, your brain cannot correctly send signals through your body. The nerves don’t function as well as they should to help you move and feel. As a result, symptoms can include fatigue, trouble walking, muscle weakness or spasm, or numbness and tingling.

Some with multiple sclerosis have blurred or double vision, while others report sexual problems, poor bladder or bowel control, pain, depression, or troubling focusing.

Multiple sclerosis is common

Multiple sclerosis (MS) is the most common disabling neurological condition of young adults worldwide. You can develop MS at any age, but most with the condition receive diagnoses between 20 and 50.

The rates of multiple sclerosis go up as one moves away from the equator. In the southern states of the United States (below the 37th parallel), the incidence of multiple sclerosis is between 57 and 78 cases per 100,000 people. The rate is twice as high in northern states at approximately 110 to 140 cases per 100,000.

Canada, Denmark, Sweden, Hungary, Cyprus, and the United Kingdom have the highest risks worldwide.

Climate matters, too, with the risk of MS higher in regions with colder climates. Those of Northern European descent have the highest risk, irrespective of their geography. On the other hand, the lowest risk is among Native Americans, Africans, and Asians.

Women are more likely than men to suffer from multiple sclerosis. Far more women have MS — the National Multiple Sclerosis Society observes that multiple sclerosis is two to three times more common in women than men. Healthline.com offers other risk factors.

There may be a genetic predisposition to getting multiple sclerosis. For example, among identical twins, if one sibling has MS, the odds are about one in three that the other will have it, too. There appear to be both environmental and inherited components to multiple sclerosis.

Even though multiple sclerosis includes so-called relapsing, remitting, or progressive types, the course and rate of the condition are rarely predictable.

Multiple sclerosis and Epstein-Barr virus

Did you know that the Epstein-Barr virus (EBV) is a member of the herpes family? EBV is one of the most common viruses in the world. Common symptoms include fever, rash, body aches, swollen glands, and sore throat — problems associated with mononucleosis.

While there is no cure for multiple sclerosis, we may be much closer to understanding why MS occurs. According to a study led by Harvard T.H. Chan School of Public Health researchers,

The Epstein-Barr virus (which infects more than 90 percent of adults and causes the “kissing disease”) and multiple sclerosis are linked.

This study is the first “providing compelling evidence of causality,” according to the study’s senior author, Dr. Alberto Ascherio.

The researchers observed 955 active service members in the United States military who had a diagnosis of multiple sclerosis. The researchers discovered that those found with the Epstein-Barr virus were 32-times more likely to have developed MS. No other virus had a similar effect.

Observes Dr. Ascherio:

“This is a big step because it suggests stopping EBV infection could prevent MS; targeting EBV could lead to the discovery of a cure for MS.”

Thank you for joining me today in exploring this breakthrough in understanding multiple sclerosis.