An outbreak of shingles?

7 of 101 staff within one department of a large office complex had shingles, as diagnosed by a general practitioner, within a three-month period. This incidence was significantly greater than that in the remaining workforce. Varicella-zoster-specific IgM antibody was detected in all 4 cases from whom early convalescent serum samples were obtained but in none of 22 controls. Within the index department there was evidence of clustering in time and by work area. A case/control study showed that a recent preceeding illness might have been a risk factor for shingles in the outbreak cases, but not for sporadic cases in other departments of the same office complex. This outbreak suggests that shingles can be provoked by reexposure to varicella-zoster virus.