Multiple sclerosis, which can cause severe disability, may be linked to Epstein-Barr virus, according to a new study. Photo by 27707/Pixabay
Jan. 13 (UPI) -- Getting infected with the Epstein-Barr virus increases a person's risk of developing multiple sclerosis later, a study published Thursday by Science found.
Among 10 million U.S. military personnel included in the analysis, 955 cases of multiple sclerosis were reported, the data showed.
Of 801 study participants with MS for whom blood samples were available, all but one tested positive for Epstein-Barr virus, the researchers said.
Based on the findings, they estimated that Epstein-Barr virus infection raises a person's risk for later developing MS by 32-fold, or more than 3,000%.
A similar risk increase was not seen with any other common viruses, including cytomegalovirus, or CMV, according to the researchers.
"Multiple sclerosis is, in fact, a complication of infection with the Epstein-Barr virus," study co-author Dr. Alberto Ascherio told UPI in an email.
"The immune response against Epstein-Barr virus infection almost certainly plays a role in [MS] disease development and progression," said Ascherio, a professor of epidemiology and nutrition at Harvard T.H. Chan School of Public Health in Boston.
More than 90% globally are carriers of the Epstein-Barr virus, a type of herpesvirus that causes infectious mononucleosis in up to half of those infected, according to the Centers for Disease Control and Prevention.
It spreads primarily through bodily fluids, particularly saliva, and most of those infected do not know they have it, the agency says.
Multiple sclerosis is an autoimmune disorder, meaning it occurs because the body's immune system attacks the protective covering of the nerve cells in the brain, optic nerve and spinal cord, called the myelin sheath, in error, according to the American Academy of Neurology.
The damage caused by this immune response disrupts the ability of parts of the nervous system to transmit signals, resulting in physical disability, particularly difficulty walking, the academy says.
Nearly 1 million people in the United States have been diagnosed with MS, many of them when they were in their 20s or 30s, the National MS Society estimates.
Researchers have theorized for years that there are links between Epstein-Barr and MS, but only recently have studies found high rates of past infection among those with the movement disorder.
For this study, Ascherio and his colleagues analyzed data on 10 million U.S. military personnel, more than 90% of whom were age 40 years and younger.
There were 955 cases of MS, with blood samples available for 801 of them, the researchers said.
The researchers tested the blood samples for Epstein-Barr virus and CMV, another often asymptomatic virus carried by those infected for life, among others, and compared the findings with those of more than 2,000 healthy controls.
While all but one of the 801 people with MS tested positive for Epstein-Barr, fewer than 10% of 342 participants with the autoimmune disorder had been infected with CMV, the data showed.