The Epstein-Barr virus (EBV), also known as human herpesvirus 4, is the primary cause of the infectious mononucleosis, which is also known as glandular fever. Back when I was a kid, it was commonly known as the kissing disease, because it is transmitted through saliva. It is most common among high school and university aged students, but young children can also become infected by saliva on toys, shared cups or the hands of carers. Typical symptoms are fatigue, fever, sore throat with deposits of fluid around the tonsils and pharynx, enlarged lymph nodes and less commonly, enlargement of the spleen and rarely, jaundice. These symptoms usually develop four to six weeks after infection with EBV, and can last for months; however, only about 25-50% of people infected will develop symptoms. There is no treatment; people recover spontaneously1,2.
EBV is one of the most common human viruses and is found all over the world. Most people get infected with EBV at some point in their lives, and it is estimated that 95% of adults carry the virus3. It has long been suspected of being a cause of Multiple Sclerosis (MS); a chronic) disease of the central nervous system. In this disease, myelin, the fatty tissue that surrounds and protects nerve fibres, is destroyed in many places. This loss of myelin forms scar tissue called plaques or lesions (sclerosis). When the nerves are damaged in this way, they can’t conduct electrical impulses to and from the brain, such that muscles do not work as they should, and usually results in pain and paralysis4. MS affects about 2.8 million people worldwide, and it has previously been shown that infectious mononucleosis (glandular fever) are at slightly increased risk of developing MS4.
In September 2021, a paper was published in the journal ‘Science’5. In this paper, scientists at Harvard University used two decades of blood samples from more than 10 million young adults on active duty in the U.S. armed forces (the samples were taken for routine HIV testing). About 5 percent of those individuals (several hundred thousand people) tested negative for EBV when they started military service, and 955 eventually developed MS. Of these, they were able to assemble appropriate samples for 801 individuals with the disease and 1,566 controls. Thirty-five of the people who developed MS and 107 controls tested negative for EBV initially. Only one of the 801 people with MS had not been infected with Epstein-Barr before the disease’s onset. The researchers were able to compare the outcomes of those who were subsequently infected and those who were not. The results showed that the risk of MS increased 32-fold after infection with EBV but not after infection with other viruses. Their conclusion was that “these findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS”4.
In accompanying commentary, immunologists William H. Robinson and Lawrence Steinman, both at Stanford University, wrote, “These findings provide compelling data that implicate EBV as the trigger for the development of MS.” Epidemiologist Alberto Ascherio, senior author of the new study, says, “The bottom line is almost: if you’re not infected with EBV, you don’t get MS. It’s rare to get such black-and-white results.” Virologist Jeffrey Cohen noted that it still needs to be shown that preventing infection by EBV will prevent MS and said that in “the original studies done with cigarette smoking and lung cancer, they found a 25-fold risk factor for people who smoked more than 25 cigarettes a day. …This is even higher”6.
In the United States, chronic diseases cause 70 percent of all deaths. Yet the factors that cause many of these conditions have been poorly understood until relatively recently. Advances in detection and diagnostic techniques have revealed that several chronic illnesses result from infectious agents. For example, the human papillomavirus causes more than 90 percent of cervical cancers (this was one of the first examples where the connection was demonstrated). The hepatitis B virus accounts for more than 60 percent of liver cancer. In addition to MS (see above), the EBV produces in people simultaneously infected with malaria, a cancer known as Burkitt’s lymphoma, a leading cause of childhood cancer deaths globally. The bacterium Helicobacter pylori has been linked to a number of disorders, including duodenal ulcers (I had one of these many years ago), gastric cancer, and certain types of lymphomas7. Many other connections between infectious agents and chronic diseases are suspected, but have not yet been demonstrated. I suspect many of them will soon be.