Multiple sclerosis, often called MS, is a long-term disease that affects the brain and spinal cord. It happens when the body’s immune system mistakenly attacks its own nerve cells.
In particular, it damages a protective covering called myelin, which surrounds the nerves. Myelin helps signals travel quickly and smoothly through the nervous system.
When it is damaged, these signals slow down or stop, leading to problems such as weakness, poor balance, vision issues, and difficulty thinking clearly.
MS affects about 2.8 million people worldwide. It is considered a progressive disease, which means it can get worse over time. Some people experience mild symptoms, while others may develop serious disabilities. For many years, scientists have tried to understand what causes MS, but the exact reason has remained unclear.
A new study from researchers at Harvard University has now provided strong evidence pointing to a major cause of the disease. The study suggests that infection with a very common virus, called the Epstein-Barr virus, or EBV, plays a key role in the development of MS.
EBV is part of the herpes virus family. It is extremely common, and about 95 percent of adults around the world have been infected with it at some point in their lives. Many people get EBV during childhood and do not even notice it.
In some cases, especially in teenagers and young adults, it can cause a condition known as infectious mononucleosis, or “mono,” which leads to symptoms like fatigue, fever, and sore throat.
After a person is infected, EBV stays in the body for life. It usually remains inactive, but it can still interact with the immune system in complex ways. Scientists have long suspected that EBV might be linked to MS, but proving this connection has been very difficult.
One reason is that EBV is so common, while MS is relatively rare. Another reason is that MS often develops many years after the initial infection.
To better understand this link, the researchers carried out a very large and detailed study. They analyzed health records from more than 10 million young adults serving in the United States military. This group provided a unique opportunity for research because regular health data and blood samples were collected over time.
Among these individuals, 955 people were diagnosed with MS during their service. The researchers studied blood samples taken every two years to see when each person became infected with EBV and how this related to the development of MS.
The results were very clear. The risk of developing MS increased by 32 times after a person became infected with EBV. In contrast, infection with other viruses did not show the same effect. This strong difference suggests that EBV is not just linked to MS but is likely a main cause of the disease.
The researchers also looked at a marker in the blood called neurofilament light chain. This marker shows when nerve damage is happening. They found that levels of this marker increased only after EBV infection, not before. This provides further evidence that the virus is involved in the process that leads to nerve damage in MS.
One interesting question is why MS symptoms often appear many years after EBV infection. The researchers suggest that the disease may begin in a very subtle way that is hard to detect at first. Over time, the interaction between the virus and the immune system may slowly lead to more noticeable damage.
This discovery is important because it opens new possibilities for preventing and treating MS. At present, there is no cure for the disease, and treatments mainly focus on managing symptoms and slowing its progression. However, if EBV is a main cause, then targeting this virus could change the way MS is treated.
For example, developing a vaccine to prevent EBV infection could greatly reduce the number of MS cases in the future. Similarly, antiviral drugs that target EBV might help stop the disease from developing or progressing.
The findings also suggest that EBV may play a role in other autoimmune diseases. This means that studying this virus could have wider benefits for understanding how the immune system works and how it sometimes goes wrong.
The study was led by Professor Alberto Ascherio and published in the journal Science. It represents one of the strongest pieces of evidence so far about the cause of MS.
This research gives new hope to millions of people living with MS and to those at risk of developing it. By understanding the root cause of the disease, scientists are one step closer to finding better ways to prevent and treat it in the future.
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