A large U.K. survey assessing the frequency of chickenpox and shingles in multiple sclerosis (MS) patients suggests a link between these diseases and MS, researchers report, suggesting their findings could help in decisions regarding immunosuppressive treatments and varicella-zoster virus vaccinations.
Results of the study “Prevalence of a history of prior varicella/herpes zoster infection in multiple sclerosis” were published in the Journal of Neurovirology.
The exact cause of MS eludes scientists, but several studies show the disease is based on complex interactions between environmental and genetic risk factors. Among environmental factors, several viruses have been implicated in MS development.
The varicella-zoster virus (VZV), which causes chickenpox, remains in the body after a first infection, staying dormant in nerves around the spinal cord. Later in life, the virus can reactivate and cause a disease known as shingles.
Shingles occurs more frequently in immune-compromised individuals, and treatment with newer disease-modifying and immunosuppressive medications in MS patients have been linked to the virus’ reactivation.
Long-lasting immunity to VZV infection is mediated by T-cells (a type of immune cell that fights infection), and newer treatments targeting T-cells can potentially reduce immune responses against VZV.
“Given that the use of new generation disease-modifying treatment is rapidly growing and that these treatments are known or likely to affect immune surveillance and responses against VZV, it is important to know the prevalence of a history of VZV exposure, as a primary infection (i.e., a history of chickenpox) or as a reactivation (zoster) [shingles] in MS patients,” the team wrote.
To assess the frequency of chickenpox and shingles in MS patients, researchers surveyed using questionnaires 1,206 randomly selected MS patients registered with the Nottingham University Hospital MS clinics.
Answers were returned from 605 patients, with a mean age of 53. None were using immunosuppressive treatments.
The majority — 86 percent — reported having had chickenpox, which is comparable with what is expected for the general population. Seventeen patients (3 percent) reported that the episode of chickenpox occurred after the onset of MS.
“The existence of a minority of MS patients who have not been exposed to VZV and who acquire the primary infection after the onset of MS needs to be taken into account in therapeutic decision-making processes,” the researchers wrote.
“It also suggests that vaccination against herpes zoster could be considered in people with MS, in particular in those about to be treated with disease-modifying drugs potentially affecting VZV responses,” they added.
Of the 594 patients who answered the shingles part of the questionnaire, 104 (17 percent) reported at least one episode of shingles. Researchers found this figure to be higher than expected in a matched general population — and noted that no difference in shingles rates was seen between male and female patients.
“The higher frequency of shingles in our MS population cannot be explained by the higher proportion of females, suggesting a real difference,” they wrote.
More than half of the patients with history of shingles also had the disease prior to developing MS.
“The substantial proportion of subjects who had a history of zoster before the development of MS suggests the virus as a possible risk factor for MS or marker of an immune response that predisposes to MS. Moreover, a history of zoster infection seems to be more common in people with MS than would be expected in a general MS population,” the team concluded.