[Clinical varicella-zoster virus reinfection observed in two advanced-age persons]

We observed two mild varicella cases of an advanced-age man and woman, although varicella in the adult generally presents a more severe course than in the child. The cases had been exposed to his great-grandchild and her grandchild with varicella in their home. They did not experience neuralgia as is typical from herpes zoster. Serological examinations revealed that they had high IgG-antibodies (Ab) against varicella-zoster virus (VZV), but low anti-VZV IgM-Ab. They were also found to have a high level of Ab against VZV soluble antigens (Ag) which are generally low in primary VZV infection. Immunoblotting analysis of anti-VZV IgG-Abs using sera from case 1 or 2 showed that their reaction patterns resembled those of sera children who contracted mild varicella after immunization with varicella vaccine and a herpes zoster-patient rather than those of sera from an immunocompetent adult with varicella. These results of serological examinations and their clinical course indicated that the cases had contracted varicella in the past and were again exposed to VZV resulting in clinically overt but mild varicella.