Varicella zoster virus in progressive forms of multiple sclerosis
Objective: Methods: In the present study we analyzed the presence of VZV in patients wit progressive forms of MS; DNA from VZV was searched by real-time PCR in blood lymphocytes and in CSF of 20 patients with progressive MS. Ultrastructural study searching for viral particles in CSF was made with transmission electron microscopy.
Results: VZVDNAwas found in the CSF from 65% of cases with progressive MS- and VZV-like viral particles were found in 30% of these patients. Nonetheless, the amount of DNA and the number of viral particles were lower than those that have been found in MS patients with R/R at the time of relapse, but higher than those found during remission.
Conclusion: Similar to findings in patients with R/R MS, VZV might be associated to progressive MS, but in minor quantity. In these cases, the virus may produce a chronic, relentless infection or trigger a process of immune-mediated demyelination.
Multiple sclerosis: Geoepidemiology, genetics and the environment
Multiple sclerosis (MS) is a chronic immune-mediated demyelinating disease of the central nervous system characterized by relapses and remissions. The risk of acquiring this complex disease is associated with exposure to environmental factors in genetically susceptible individuals. The epidemiology of MS has been extensively studied. We review the geographic epidemiology of the disease, the influence of immigration, age at immigration, clustering and epidemics. Various presumptive risk factors are discussed such as ultraviolet radiation, vitamin D, Epstein–Barr virus and infectious mononucleosis, other infectious agents and non-infectious factors. Two different hypotheses, the hygiene hypothesis and the prevalence hypothesis, were proposed to explain these environmental risk factors for MS. The epidemiological data, combined with pathological and immunological data, may contribute to the debate whether MS is an autoimmune disease, a latent or persistent viral disease, or a neurodegenerative disease.