Study of virus isolation from pharyngeal swabs in children with varicella.

We performed virus isolations from the pharyngeal swabs in 117 children with varicella who were aged from 22 days to 15 years and 70 healthy children who were aged from 3 months to 15 years, by using human embryonic lung cell cultures. Viral isolates were confirmed by an indirect immunofluorescence method or by neutralization with well-characterized antibodies. Five varicella-zoster virus isolates (4.3%), 23 cytomegalovirus isolates (19.7%), five herpes simplex virus isolates (4.3%), and one respiratory syncytial virus isolate (0.9%) were found in the patients with varicella. Ten cytomegalovirus isolates (14.3%), two herpes simplex virus isolates (2.9%), one respiratory syncytial virus isolate (1.4%), and one poliovirus isolate (1.4%) were found in the swabs of the healthy control children. The varicella-zoster virus isolation rate from the pharyngeal swabs in children with varicella was low as compared with the rate from those pharyngeal swabs in the children with cytomegalovirus and herpes simplex virus. No varicella-zoster virus isolates could be found in the swabbed materials after filtration (0.45 microns). On the other hand, cytomegalovirus and herpes simplex virus could be isolated from the filtrated swabs, as well as from the unfiltrated swabs. The method of testing by filtration could have affected the results.