研究发现EB病毒跟多发性硬化症有关

Researchers have found more evidence that one of the world's most common viruses may be linked to the disease multiple sclerosis.

MS causes the body's own immune system to mistakenly attack nerve cells. It destroys the protective material that covers nerve tissue.

The Epstein-Barr virus has long been suspected of playing a part in development of MS. But a connection is hard to prove because just about everybody gets infected with Epstein-Barr but few develop MS.

Last week, Harvard researchers reported one of the largest studies yet to support the possible link between the virus and MS. They studied a supply of blood samples from usual medical tests on more than 10 million members of the American military. The samples cover a period from 1993 to 2013. The scientists searched the samples for antibodies signaling viral infection.

They found that the risk of MS increased by 32 times following Epstein-Barr infection.

Only 5.3 percent of the sampled group were free of signs of the virus when they joined the military. The researchers compared 801 MS cases found later over the 20-year period with 1,566 service members who never got MS.

Only one of the MS patients had no evidence of the Epstein-Barr virus before their MS diagnosis. And the researchers found no evidence that other viral infections were involved.

The findings "strongly suggest" that Epstein-Barr infection is "a cause and not a consequence of MS," study leader Alberto Ascherio and his team reported in the publication Science. Dr. Ascherio is with the Harvard T.H. Chan School of Public Health.

The virus appears to be "the initial trigger," Dr. William H. Robinson and Dr. Lawrence Steinman of Stanford University wrote in a report alongside the study.

Epstein-Barr is best known for causing "mono," or infectious mononucleosis, in teenagers and young adults. The virus remains inactive in the body after infection and has been linked to later development of some autoimmune diseases, including MS, and rare cancers.

It is not clear why. Some scientists think the body is tricked by viral proteins that look very much like nerve proteins.

Whatever the cause may be, the new study is "the strongest evidence to date that Epstein-Barr contributes to cause MS," said Mark Allegretta. He is vice president for research at the National Multiple Sclerosis Society.

He added that the evidence, "opens the door to potentially prevent MS by preventing Epstein-Barr infection."

I'm Caty Weaver.

The Associated Press reported this story. Caty Weaver adapted it for VOA Learning English.

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sample –n. a small amount of something that gives you information about the thing it was taken from

diagnosis –n. the act of identifying a disease, illness, or problem by examining someone or something

consequence –n. something that happens as a result of a particular action or set of conditions

initial –adj. occurring at the beginning of something

trigger –n. something that causes something else to happen

contribute –v. to help to cause something to happen

potentially –adj. in a possible state or condition — used to describe the possible results or effects of something