Genotype of prevalent varicella-zoster virus in Ningbo city

Objective To examine the epidemiological characteristics of varicella and to detect the genotype of varicellazoster virus for developing strategies of varicella prevention and control in Ningbo.Methods Graphs and appropriate statistics were used to describe the epidemiological characteristics of chickenpox cases extracted from the China Disease Prevention and Control Information System.Meanwhile herpes specimen were collected from clinically diagnosed cases and genotypes of varicella-zoster virus were determined with polymerase chain reaction(PCR)technique.Results The reported incidence of varicella in Ningbo was 23.33/100 000 in 2009 and 26.24/100 000 in 2010,respectively.Most of the patients were children aged 7-12 years and the epidemic peaks were in May,June,November and December.The genotypes of 15 DNA specimens were 13 J-type and 2 M1-type.Conclusion Varicella cases in Ningbo occurred mainly in winter and spring seasons and most of the cases were children aged 7 to 12 years.The predominant strain circulated in Ningbo is J-type,with M1type strain isolated sporadically.