Herpesviruses: Emerging Nosocomial Pathogens?

Background : Herpesviruses are ubiquitous pathogens that are known to cause infection in humans and animals. It is likely that more than 90% of adults have been infected by one or more herpesviruses. As hospitalized patients become increasingly immunosuppressed by virtue of illness or therapies, it is increasingly likely that human herpesvirus infection will become manifest in the hospital. Whether these manifestations represent manifestations of reactivated latent disease or true nosocomial infections is an open question. Methods : Review of the pertinent English-language literature. Results : There are eight known herpesviruses that cause disease in humans. Herpesviruses are double-stranded DNA viruses. The prototypical structure consists of an inner DNA core that is encased within a nucleocapsid that is icosahedral in configuration and consists of capsomere subunits. Herpesvirus infection generally occurs when virus is transmitted in oral secretions from an infected to a naive host. Clinical reactivation syndromes can occur in transplant patients, cancer chemotherapy patients, and patients with acquired immunodeficiency syndrome. Life-threatening infections are most closely associated with human herpesvirus-5 (cytomegalovirus), whereas the relationships between human herpesvirus-7 and clinical disease are largely undefined. Conclusion : Clinical expressions of herpesvirus in surgical patients are not nosocomial infections, but are in the vast majority of cases the reactivation of latent infection. Reactivation disease can be lethal to the immunosuppressed host.