OBJECTIVETo study the incidence of human cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6) infection in pediatric patients with hemopoietic stem cell transplantation (HSCT), and to explore the relationship between CMV and HHV-6 infection in pediatric patients with HSCT.

METHODSPediatric patients with HSCT in hemotology center of Beijing Children's Hospital were enrolled into this study from June 2007 to October 2009. Peripheral blood were collected every week after HSCT, and Fluorescent quantitation PCR and conventional PCR were used to detect CMV DNA load in serum and HHV-6 DNA in peripheral blood respectively. Genetic typing was conducted on HHV-6.

RESULTSFifty two pediatric patients with HSCT were enrolled into this study, and six hundreds and thirty six specimens were collected totally. CMV DNA was detected in fifty two specimens from twenty cases. The median time was 56 days after HSCT. The incidence of CMV infection was 38.5% (20/52) in all HSCT patients and 47.6% (20/42) in allogene HSCT patients. The incidence of late CMV infection was 22.2% (6/27) in allogene HSCT. Three patients died of CMV infection,and two died of CMV interstitial pneumonia. HHV-6 DNA was detected in thirty three specimens from fourteen cases. The median time was 23 days after HSCT. The incidence of HHV-6 infection was 26.9% (14/52)in all HSCT patients and 31% (13/42) in allogene HSCT patients. The genotype of HHV6 was all type B. HHV-6 DNA was positive in six of twenty cases with CMV infection. The incidence of co-infection was 30% (6/20).

CONCLUSIONSThere was a substantial incidence of CMV and HHV6 infection after HSCT. The relationship between earlier HHV6 infection and later CMV infection in pediatric patients with HSCT need further study.