Multiple sclerosis (MS) may be linked to the combined effects of a viral infection and not getting enough sun, research suggests.
A study found that, together, the two factors accounted for 72 per cent of variations in MS occurrence across the UK.
Levels of sunlight exposure alone explained 61 per cent of the difference between high and low rates of MS.
Previously, it was known that people with a history of glandular fever, a common infectious illness caused by the Epstein-Barr virus, were more at risk of MS.
A pattern of higher incidence had also been seen in individuals whose skin is exposed to little sunlight.
“We wanted to see whether the two together would help explain the variance in the disease across the United Kingdom,” lead researcher George Ebers, of Oxford University, said.