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Today during the comorbidities in RA session, Dr. Leonard Calabrese spoke about herpes zoster (HZ). Given the frequency of HZ in immunocompetent persons and the fact that patients with IMIDs carry at least twice the risk of developing HZ, it is important for rheumatologists to be informed about diagnosis, treatment and most importantly prevention of HZ. We all can recognize the classic vesicular rash of HZ so diagnosis is often made clinically. However, there are cases when the diagnosis is not so clear, including during the prodromal phase, early rash that may resemble HSV infection, contact dermatitis or CA-MRSA, and cases of HZ sine herpete, which occurs ~2% of the time.
Perhaps the most important reason why rheumatologists should be concerned about HZ is because of the complications, which are numerous and include post-herpetic neuralgia, motor neuropathy, cranial palsy, encephalitis, transverse myelitis and stroke. Numerous groups have recently reported the risk of stroke after HZ, in particular in the first 3 months following infection (Calabrese LH, et al. A&R 2017;69(2):439-46).
As far as treatment, we recommend that all immunocompromised hosts be treated with antivirals (acyclovir, valacyclovir, famciclovir) even if symptoms have been present for > 72 hours, as there is a low ratio of harm-to-benefit and treatment can decrease pain, promote healing and decrease shedding. It remains unclear whether or not antiviral treatment reduces risk of PHN. Complicated HZ (disseminated, CNS, visceral, opthalmic) requires hospital admission and IV antiviral therapy.
In terms of prevention, as Calabrese put it – “the best strategy for preventing complications of HZ is to prevent HZ”. While the live-attenuated herpes zoster vaccine (Zostavax) is contraindicated in the setting of most immunosuppression, the footnotes of the 2017 ACIP recommendations for vaccination state it can be given in the following instances: if not on a biologic, if taking the equivalent of prednisone 20 mg/d or less, or traditional doses if MTX or AZA. Regardless, our Zostavax administration rate remains ~ 5%. There are many reasons for this, including uncertainty of optimal timing, as vaccine efficacy wanes significantly after 5 years. At present time there is a HZ subunit vaccine in the late stages of clinical trials and the data look quite promising as far as duration of immunogenicity and efficacy in older adults (Cunningham AL, NEJM 2016;375:1019-32). Stay tuned.