With the introduction of protease inhibitors, increasing rates of herpes zoster were noted in HIV-infected patients. Two studies comparing ART and non-ART patients reported increased incident cases of zoster and rates estimated at 6.2-9.0 cases per 100 person-years, three to five times higher than rates observed in the pre-HAART era [18, 71] . While another study [72] reported no difference in overall incidence between HAART eras (3.2 cases per 100 person-years), the use of HAART was associated with increased odds of developing an incident zoster outbreak (OR = 2.19, 95% confidence interval: 1.49 to 3.20). These studies suggest that ART may play a role in increasing the risk of zoster, which is reflected in large observational IRIS cohorts, where dermatomal varicella zoster comprises 9-40% of IRIS cases [4, 32, 33] . Mean onset of disease from ART initiation was 5 weeks (range 1-17 weeks) [71] , and no cases occurred before 4 weeks of therapy [18] . Both studies identified significant increases in CD8 T cells as a risk factor for developing dermatomal zoster.