Multiple sclerosis (MS) is a severe persistent condition of the central nervous system in which the coating around nerve fibres (myelin) is damaged, causing a wide range of distressing symptoms varying in severity.

At any given time, it affects around 3 million people worldwide.

The cause of MS is unknown; however, it is believed to occur as a result of some combination of genetic and environmental factors such as infectious agents. Theories try to combine the data into likely explanations, but none has proved definitive. While there are a number of environmental risk factors and although some are partly modifiable, further research is needed to determine whether their elimination can prevent MS"

Source : Wikipedia

The risk factors known to influence the likelihood of becoming affected include :

• Genes and family history
• Environmental factors
• Viral infections
• Vitamin D deficiencies
• Smoking
• Obesity

(Source :MS Society, UK) There may well be other as-yet-undiscovered contributing factors.

A 2022 report in the journal Science suggests that there may be links with previous infections of the Epstein-Barr Virus (EBV) - the cause of Mononucleosis, a.k.a Glandular Fever.

Risk of MS increased 32-fold after infection with EBV but was not increased after infection with other viruses, including the similarly transmitted cytomegalovirus. Serum levels of neurofilament light chain, a biomarker of neuroaxonal degeneration, increased only after EBV seroconversion. These findings cannot be explained by any known risk factor for MS and suggest EBV as the leading cause of MS.

See : Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis Science, Vol. 375, No. 6578

However, roughly 90% of the human population has at some stage been infected with EBV, and yet the vast majority do not go on to develop MS.