An algorithm for the control of nosocomial varicella-zoster virus infection.

Inadvertent or uncontrolled introduction of varicella-zoster virus into the hospital environment occurs commonly and must be investigated in a systematic and efficient manner to minimize secondary spread to patients (particularly the immunocompromised) or hospital personnel. On the basis of a review of the literature and our practical experience with 11 such exposures to varicella-zoster virus during a 2-year period, we have developed a working algorithm for such investigations. Index cases most often are children, resident physicians, students, young nurses, and ancillary personnel, or adult patients with herpes zoster. A negative or uncertain past history of this infection is an unreliable predictor of susceptibility among the exposed and should be confirmed by serology tests or delayed hypersensitivity skin testing. An incubation-contagion timetable, coupled with a stratification of risk among the exposed, permits a prioritized response in dealing with an introduction of varicella-zoster virus. The preemployment screening of all hospital workers for susceptibility to varicella-zoster virus should be considered as a practical and cost effective policy.