MS Risk and the Herpes Virus: Is There a Link?

Doctors and researchers still do not know what causes multiple sclerosis (MS). Some factors imply that an infectious agent, like a virus, may have a role in triggering MS. These factors include:1

  • An identical twin of someone with MS has a 1 in 4 chance of also getting MS. Identical twins have almost identical genetics. So, this implies genetics is not the only cause.
  • Data from research that studies factors like location, gender, and wealth of who has MS suggests that an infectious agent may trigger the disease.
  • About 90 to 95 percent of people with MS have specific proteins in their spinal fluid. These proteins are also found in people who have central nervous system diseases that are caused by viruses.

Despite these factors, so far scientists have not found a specific virus that triggers MS. But 1 family of viruses they have considered is the herpes virus.1

What is the herpes virus?

There are over 100 different types of herpes viruses that we know of. They can cause diseases in many different animals. Only 8 of the herpes viruses typically infect people. Different types of these 8 herpes viruses are responsible for common conditions like cold sores or chicken pox.2,3

Unlike some diseases, the herpes virus remains in your body even if you are not showing symptoms. This is when the virus is in a latent state. However, it will sometimes reactivate. This can cause new symptoms or conditions. For example, when the virus that causes chicken pox reactivates, it causes shingles.2,3

What type of herpes are linked to MS?

Researchers think 2 of the herpes viruses that infect people may be linked to MS. These are Epstein-Barr virus (EBV) and human herpes virus 6 (HHV-6).1

At the time of the infections, EBV and HHV-6 may often look like any other illness. They cause symptoms like fever, tiredness, and flushed cheeks. Most people get these diseases at some point in their lives. We do not know how HHV-6 spreads. But EBV spreads through bodily fluids, like saliva.2,3

What evidence links EBV to MS?

Researchers are still investigating any possible link between EBV and MS. However, some research does point to a connection. One study found that people with high levels of EBV antibodies and a specific gene were 9 times more likely to develop MS than those without the EBV antibodies. Antibodies are immune proteins that prove a person has had a certain illness.1,4

Other research found that EBV antibody levels were much higher in people who eventually develop MS than those who do not. In addition, a study of more than 10 million young adults found that the risk of MS increased over 32 times after having EBV. In the study, no other virus caused such an increase.1,4

What evidence links HHV-6 to MS?

The research linking HHV-6 and MS is also ongoing. One research review found that 90 percent of the studies that investigated MS and HHV-6 found a link. For example, one study compared evidence of virus infection in people with and without MS. This study found that the presence of HHV-6 DNA was the best predictor of the risk of developing MS of all the viruses studied.5,6

Despite these findings, we still do not know for sure if EBV or HHV-6 causes MS. We also do not know exactly how these viruses could be causing MS. More research is needed to link any kind of herpes virus to MS.1

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