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.
Australia's government has invited backpackers and students to seek work in the country. "Backpackers" are mostly younger people who travel in a simple way and do not spend very much money.
The move is an effort to fill critical workforce shortages as Australia faces an outbreak of the Omicron variant of COVID-19.
Prime Minister Scott Morrison on Wednesday said his government would not require backpackers or students arriving in the next several weeks to pay the usual $453 visa cost. He also urged such visitors to seek work as they travel around the country.
"Come on down now because you wanted to come to Australia," Morrison said during a televised press conference.
He added that the backpackers and students could seek work in agriculture, hospitality and "so many other parts of the economy" that lack enough workers.
The announcement comes as Morrison faces criticism at the beginning of an election year. Critics say he has not done well in dealing with the Omicron outbreak.
Australia is experiencing record numbers of new infections and deaths. Officials in Australia reported 67 new deaths and nearly 80,000 new cases on Wednesday. Chief Health Officer Paul Kelly said Australians should expect the pandemic's total death numbers to rise.
Australian businesses are struggling with the growing number of workers who are sick or ordered to isolate. The labor shortage has led to supply shortages. Food stores have put in place purchase limits on some goods.
Rising hospitalizations have put pressure on the health system. Nearly 1.3 million cases of the country's total of 1.6 million cases have been reported in the past two weeks.
Morrison is also facing criticism over the shortage of at-home rapid tests. On Wednesday, he urged state leaders to drop any requirements for workers in most industries to take daily rapid tests. The federal government also promised to buy 52 million tests this month from Asia and the United States.
As the country faces a shortage of tests, police on Wednesday said 42,000 tests worth about $500,000 were stolen from a freight station in Sydney.
I'm Ashley Thompson.