Evidence from epidemiological studies of a role for any of the many common infections in the aetiology of MS is largely inconsistent [3, 6] . This could be due to the prolonged silent stage of the disease, but recent studies on MS commencing in childhood might be able to shed light on this issue [6, [12] [13] [14] . Although there is no convincing evidence that any specific active infection directly causes MS, at least 14 specified infections have demonstrable associations with this disease on the basis of serological characteristics [2, 3, 6, [12] [13] [14] [15] , with Epstein-Barr virus (EBV) emerging as the most likely single candidate for a leading aetiological role [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] . This infection is unique in that the prevalence of specific antibody is consistently higher in children with MS as compared with healthy agematched controls [12] [13] [14] , whereas at the typical age of onset of MS (late 20s to early 30s) nearly all patients and control subjects have already experienced EBV infection. The two key points to emerge from these studies in relation to EBV are that all children with MS had already been infected with EBV [12] [13] [14] , and that the levels of antibody against the EBV EBNA1 antigen were very significantly higher in both adults and children with MS as compared with controls [13, 14, 16, [23] [24] [25] . In this context, infections with EBV usually occur in infancy in the developing nations where MS is rare while in the industrialised nations infection usually occurs later in life, often being delayed until adolescence or early adulthood.