Susceptibility to varicella zoster virus infection in health care workers.

Varicella zoster virus (VZV) is an occupational hazard for a percentage of health care staff. Nine hundred and seventy staff members attending the Occupational Health Department at Cork University Hospital took part in the survey. A latex agglutination assay was used to determine the health care workers immune status to VZV. Of the 970 workers tested, 928 (95.7%) were immune to VZV. The sensitivity, specificity and predictive value of an enquiry regarding a history of chicken-pox was determined on a sample of 206 health care workers. The positive predictive value was 95% (119/125) and the negative predictive value was 11% (4/35). The sensitivity of the enquiry was 79% (119/150), the specificity was 40% (4/10), reducing to 61% (119/195) and 36% (4/11) respectively when individuals with uncertain histories were included in the calculations. The advantages and disadvantages of selective staff screening are discussed. In the authors' opinion all health care workers involved in the clinical care of patients should be screened by serology for past VZV infection before taking up duty and those who are susceptible to VZV should be made aware of the risks and health effects associated with VZV if contracted.