OBJECTIVETo determine the plasma level of Epstein Barr virus (EBV) DNA in children with EBV associated diseases, and to investigate the dynamic changes of EBV DNA level after initial infection as well as the relationship between EBV DNA level and the diseases severity.

METHODSThe subjects consisted of 73 children with primary EBV infection (infectious mononucleosis, pneumonia,etc.) and 18 children with severe EBV-associated diseases (chronic active EBV infection, hemophagocytic lymphohistiocytosis, etc.). The plasma EBV DNA level was detected by a real-time PCR assay.

RESULTSThe plasma EBV DNA level decreased with the infection time in children with primary EBV infection. Two weeks after infection, plasma EBV DNA was almost undetectable. The positive rate of plasma EBV DNA in children with severe EBV associated diseases increased significantly when compared with that in children with primary EBV infection (89% vs 16%; p<0.05).

CONCLUSIONSThe level of EBV replication may be reduced with the infection time. Dynamic determination of blood EBV DNA is useful for the evaluation of disease severity in children with EBV infection.