title: Cytomegaloviruses: a Historical Perspective.
abstract: The cellular changes associated with the cytomegaloviruses result in enlarged cells with prominent nuclei. These were first described by pathologists and for many years they were considered to be parasitic protozoa. In 1926, however, it was suggested that the aetiological agent was probably a virus, and the viruses responsible were isolated independently by three groups in 1956. Demonstration of antigenic heterogeneity between the isolates led to the term cytomegaloviruses (CMV). Clinical studies first concentrated on overt congenital infection in CMV-infected individuals who exhibited neurological defects; however, the picture of congenital infection was altered and expanded by subsequent longitudinal studies. Asymptomatic CMV-infected newborns were often found to develop deafness. It was discovered that infected children could excrete CMV in their urine for several months and, from this source, the virus was able to spread rapidly in environments such as day-care centres. While CMV infection acquired by adults was often asymptomatic, a CMV mononucleosis syndrome was later recognized. This was followed, in 1966, by the discovery that CMV mononucleosis could develop after the transfusion of CMV-infected blood. Subsequently, CMV infection in the immunosuppressed subject became recognized as a serious cause of morbidity and mortality.
authors.affiliation: Richard Pearson Strong Professor of Tropical Public Health, Emeritus, Harvard School of Public Health, Boston, MA, USA.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Weller