The frequency of varicella-zoster virus infection in patients with multiple sclerosis receiving fingolimod.

Multiple Sclerosis (MS) is thought to be an autoimmune disease of the central nervous system (CNS), in which the immune system becomes activated, cross the blood-brain barrier (BBB), and cause neuroinflammation and neurodegeneration. Fingolimod is considered a disease-modifying therapy (DMT), possessing immunomodulatory effects on the immune system, especially autoreactive T cells being licensed in lymph nodes. Although the fidelity of the drug is undeniable in the management of disease course, various adverse effects have been reported in some patients taking this medication. In this study, 420 MS patients, consisted of 210 patients receiving interferon-beta (IFN-beta) and 210 patients receiving fingolimod therapies. As a control group, 210 age- and sex-matched healthy individuals were recruited in our study. The levels of anti-VZV IgG and IgM were determined using enzyme-linked immunosorbent assay (ELISA). The presence of VZV DNA in peripheral blood mononuclear cells (PBMCs) was also investigated using the PCR method. The percentage of seropositivity for anti-VZV IgG and anti-VZV IgM in MS patients was 94.8% and 0%, respectively in those taking fingolimod therapy. In patients receiving IFN-beta, the rate of seropositivity for anti-VZV IgG and anti-VZV IgM was 93.8% and 0%, respectively. In healthy individuals, the rate of seropositivity for anti-VZV IgG and anti-VZV IgM was 84.3% and 0%, respectively. The PCR results showed that 7.6% of patients receiving fingolimod were positive for VZV DNA, while none of the healthy subjects nor MS patients taking IFN-beta were positive for DNA of VZV. The statistical analysis indicated that the frequency of VZV DNA in patients receiving fingolimod was significantly (p = .00) higher than MS patients taking IFN-beta and healthy subjects. It seems that the use of fingolimod should be carefully prescribed as the occurrence of VZV infection/reactivation is increased in comparison to other MS patients who receive different therapy.