The varicella zoster virus: a pilot trial of a potential therapeutic agent in multiple sclerosis.

There are a number of similarities in the geographic, latitudinal, and epidemiological features of multiple sclerosis (MS) and varicella (V). In the experimental model of MS, repeated high antigen doses (myelin basic protein) have deleted both the clinical and pathological manifestations of the disease. Therefore, it seemed appropriate to explore the effects of varicella zoster vaccine on patients with MS. Fifty patients with chronic progressive MS were vaccinated with attenuated varicella virus vaccine and followed for one year. Fourteen patients improved, four became worse, and twenty-nine were unchanged. All patients were seropositive for varicella before vaccination and all had a rise in varicella antibodies after the vaccinations. There were no major untoward results from the vaccine. Four patients developed mild chicken-pox after vaccination. This was a short-term pilot trial without control subjects. Thus, the apparently favourable clinical and magnetic imaging changes must be assessed with caution, as must the lack of adverse effects.