Survey of neutralizing antibodies against EV71 and Cox A16 in healthy population in Wuqing district, Tianjin

Objective To investigate the latent infection status of enterovirus 71 (EV71) and coxasckievirus A16 (Cox A16) and related factors in healthy population in Wuqing district of Tianjin, and provide evidence for the prevention and control of hand, foot and mouth disease (HFMD). Methods Venous blood samples were collected from 230 healthy people in Wuqing for the detection of neutralizing antibodies against EV71 and Cox A16. The related factors were surveyed by using questionnaire and analyzed with 2 test. Results The antibody titer of 1:8 was used as the critical value, the positive rates of neutralizing antibodies against EV71 and Cox A16 were 73.91% (170/230) and 76.52% (176/230) respectively, the difference was not significant (2=0.420, P=0.517). The positive rate of neutralizing antibody against EV71 was highest in age groups 0- and 15- years (all 76.09%), while the positive rate of neutralizing antibody against Cox A16 was highest in age group 0- years (84.78%). The lowest positive rates were found in age groups 5- and 15- years respectively (71.74% and 69.57%). The differences in annual positive rate of neutralizing antibody against EV71 were significant (2=29.971, P=0.001). The titers of neutralizing antibodies against EV71 and Cox A16 ranged from 1:4 to 1:256, accounting for 82.61% (190/230) and 88.26% (203/230) respectively. The results of 2 test showed that the important influencing factors for the positive detection of neutralizing antibody against EV71 were particular year and habit of washing hands after return from outside; the important influencing factor for the positive detection of neutralizing antibody against Cox A16 was being preschool children. Conclusion People are generally susceptible to EV71 and Cox A16. The infections can produce specific immunity in 70.00% of healthy population. Latent infections might play an important role in the transmission of HFMD.