| Objective To know the enterovirus type71(EV71) and coxsakievirus group A type16(CVA16) neutralizing antibody (NA) level distribution of people aged0-15years and postnatal mothers, to provide baseline data for finding the initial age of EV71vaccination. Method Select3hand-foot and mouth disease (HFMD) high incidence counties and3HFMD low incidence counties in Guangxi Zhuang Autonomous Region and Jiangsu province. Then select1high incidence town and1low incidence town from each county. We selected people aged0-15years old and postnatal mothers by systematic sampling, investigated them (or their parents) by questionnaire and collected their blood. We detected the NA of EV71and CVA16by neutralizing trial. Result First, the EV71NA positive rate of general population was48.7%. It decreased with the age, and decreased at the lowest level at6months old, then it increased quickly to a high level after1year old. The curves of EV71NA positive rate among different counties and genders were similar to the total curve. The total EV71NA geometric mean titer (GMT) was1:17.70. The EV71GMTs decreased with the age, and the lowest GMT appeared at5months. After1year old, the GMT began to increase quickly. The highest level was1:95.77, which appeared at4years old group. The curves of EV71NA GMT among different counties and genders were similar to the total curve. There were statistical differences between the positive rates and GMTs of people with different histories. Second, the CVA16NA positive rate decreased gradually in<1years old groups. After1year old, the rate rise and peaked at6-10years old group. There were statistical differences among positive rates of different age groups and counties, but no statistical differences existed between rates of male and female. The GMT of all subjects was1:8.44.The GMT of0-1years old groups were all under1:10, after1year old group, the GMT increased. The highest GMT (1:22.97) appeared in group5years old. The GMT change of different age groups in each county was similar with that in all subjects. Third, compared with the CVA16NA positive rates and GMTs, except4months,5months,6months,7months,8months,1years old groups and Mengshan county, the EV71NA positive rates and GMTs were all higher. Fourth, the mothers’positive rates and GMTs of EV71and CVA16NA were83.59%、33.1%and1:26.61%1:6.11, respectively. The newborns’ positive rates and GMTs of EV71and CVA16NA were75.2%,35.5%and1:22.05,1:6.97, respectively. There were no statistical differences between the positive rates and GMTs of mothers and newborns, so were those of the high and low incidence counties. The EV71and CVA16NA titers of mothers correlate with those of newborns (rEV71=0.69, P<0.0001; rCVA1=0.4769, P<0.0001). Fifth, in part of all subjects, the EV71and CVA16NA level were both positive. The rates of both positivity, only EV71NA positivity, only CVA16NA positivity and both negativity were24.7%,23.9%,9.9%and41.4%, respectively. Conclusion First, the maternal EV71NA may decrease to the lowest at5-6months old. From1year old, the EV71infectious rate increased quickly. Second, the HFMD outbreak caused by CVA16can happen in people aged0-15years of six counties. Third, if the EV71and CVA16NA positive rates and GMT of mothers were high, those of newborns would be also high, which can provide effective protection for newborns. Fourth, the maternal EV71and CVA16NA titers are lower than the titers acquired from natural infection. Fifth, after infecting EV71or CVA16, there may be a lot of cases with silentinfection. Sixth, in the six couties, the EV71prevalence rate was higher than CVA16. |
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