Abstract:

Objective To investigate the levels of the enteroovirus 71 and C4 genetype antibody (EV71-lgG) among children in Guangzhou area, and the relationship between EV71-IgG and hand, foot and mouth disease (HFMD). Methods EV71 diagnostic antigen was prepared from EV71 C4 genotype samples isolated from children with HFMD in Children's Hospital, Guangzhou Women and Children's Medical Center to establish the method of diagnostic EV71-IgG kits and laboratory evaluation. Blood samples of healthy children confirmed to be without fever and symptoms of HFMD by physical examinations in our hospital were collected from January to March in 2010 to be tested for EV71-IgG antibody. Swab specimens were collected from outpatient and inpatient children with HFMD in our hospital in 2010 to be tested for specific EV71 nucleic acid. Results ① The cut-off value of kit established by our laborary was 0.148. Compared with the cell neutralization tests, the accordancy rate was 100% for positive rate and 92% for negative rate. There was no cross reaction with Coxsackie A16 virus antibody. ②Serum samples were from 819 healthy children, including 481 males and 338 females. EV71-IgG positive rate in children aged under 1 year was the highest (60%, 60/100), and EV71-IgG positive rates of -2-year-old, -3-year-old, -4-year-old, -5-year-old and -14-year-old groups were 39.3%（72/183）, 12.9%（15/116）, 27.1%（38/140）, 14.2%（16/113） and 22.8%（38/167）。There was no significant difference between different genders. ③ A total of 4 780 children with positive EV71 were enrolled, including 3 070 males and 1 718 females. There were 310（6.5%） children in <1-year-old group, 1 157（24.2%） in -2-year-old, 1 337（280%） in -3-year-old, 1 094（22.9%） in -4-year-old, 450（9.4%） in -5-year-old, 432（9.0%） in -14-year-old groups. ④ In each group EV71 - IgG antibody positive rate was opposite to the tendency of EV71 positive rate. In <1-year-old group, EV71 - IgG positive rate was the highest while EV71 positive rate was the lowest. In -3-year-old group, EV71 - IgG positive rate was the lowest while EV71 positive rate was the highest. Conclusions In Guangzhou area, EV71-IgG positive rate in children aged under 1 year was the highest. EV71 positive rate was significantly associated with EV71-IgG positive rate.

Key words: Children, ELISA, Enterovirus 71, Hand, foot and mouth disease