Rescue of Severely Immunocompromised HIV‐Positive Persons. Part 8
As demonstrated in this and a previous outbreak investigation, environmental sampling is useful for confirming a varicella case or outbreak, particularly in situations in which lesions are no longer present or clinical specimens would be difficult to collect and environmental specimen collection and testing are feasible. We were able to detect VZV DNA in environmental samples from case patients’ bedrooms and belongings and found that it could still be detected in the environment several months after rash onset. Other outbreak investigations have also found that VZV may possibly be spread through airborne transmission, and VZV has been detected from throat and air filter samples of herpes zoster and varicella case patients in a hospital setting. Collection of airborne particles using aerosol samplers, which has been used for detection of influenza and respiratory syncytial virus, may be a potential method for providing additional information on airborne transmission of VZV. Detection of VZV DNA in the environment should be interpreted with care, because it could result from viral shedding that occurred remotely and because detection of VZV DNA in the environment may not necessarily indicate the presence of viable infectious virus. Because clinical specimens are still the optimal method for confirmation of a varicella case and limitations in interpreting results, we do not recommend environment specimens as the routine source for laboratory testing.
This outbreak demonstrated that adults who have lived in residential settings for most of their lives are potentially susceptible to varicella disease. It is important for residential facilities to screen all current and potential residents and staff for varicella immunity prior to admission or employment and to vaccinate those who are susceptible to help prevent disease in this setting. Susceptible residents or staff who are not screened prior to admission or employment should be vaccinated within 5 days of exposure to VZV, although vaccination is recommended even after this period because vaccination will provide protection for future exposures. Staff in these facilities should remain alert for herpes zoster, as well as varicella, and implement appropriate infection control measures in a timely fashion to prevent VZV transmission to susceptible residents and staff. Laboratory testing plays an important role in determining susceptibility to varicella in adults; it can be used to confirm diagnoses in an outbreak so that adequate control measures can be implemented, and it can be used to identify vaccine adverse events.