Zoster is an important clinical problem for human immunodeficiency virus ty
pe 1 (HIV)-infected patients. Risk factors for tester and trends in inciden
ce in HIV-infected hemophiliacs and homosexual men (n = 1218) were examined
. From 1984 to 1997, 174 tester cases were identified (average yearly incid
ence, 2.5%). Prior tester episodes were associated with increased risk for
a subsequent episode (relative risk [RR], 4.30; 95% confidence interval [CI
], 3.11-5.95), Among hemophiliacs, children and adolescents had the highest
tester risk, and tester risk declined with age (RR, 0.80 per decade; 95% C
I, 0.68-0.93), These findings suggest that HIV-infected persons do not prod
uce or maintain adequate booster responses after varicella tester virus exp
osure. Zoster risk was relatively constant when CD4 cell counts >200 cells/
mm(3) but increased steeply below this level. During the 14 years of follow
-up, tester incidence declined 9% per year. This trend occurred despite dec
reasing CD4 cell counts and was unexplained by zidovudine or acyclovir use.