The Oxford English Dictionary defines opportunistic as “exploiting chances offered by immediate circumstances.”1 The term was applied to pathogens, notably fungi, first in the early 1950s, and it came into increasingly widespread use after an International Symposium on Fungal Infections led by Utz in 19622 and a meeting of the Pathology Section of the Royal Society led by Symmers in 1965.3 Symmers discussed the concept of opportunistic infections, noted that the organisms involved could include viruses, bacteria, and parasites, and presciently mentioned that these infections were “often predisposed by therapeutic measures that should heal, not harm,”3 including “use of any form of therapy that has a tendency… to interfere with the mechanisms of defense against infection.”3 An increased frequency of herpes zoster (HZ) in immunocompromised patients has long been recognized.4 Arvin et al noted that reactivation of HZ occurred in even higher frequency when patients with Hodgkin lymphoma, which was itself associated with a higher frequency of HZ, were also treated with radiation and chemotherapy5 and drew attention to the importance of depression in virus-specific cellular immunity as the predominant predisposing risk factor.6 Now, 3 decades later, Arvin and colleagues7 report on the increased incidence of varicella-zoster virus (VZV) infections in patients treated with one of the newest disease-modifying therapies (DMTs) for multiple sclerosis (MS), fingolimod.
Kenneth L. Tyler. Fingolimod and Risk of Varicella-Zoster Virus InfectionBack to the Future With an Old Infection and a New Drug. JAMA Neurol. 2015;72(1):10–13. doi:10.1001/jamaneurol.2014.3390