Seroepidemiology of poliovirus antibody among the children in Eastern Turkey.

BACKGROUND & OBJECTIVE Data on immunization are generally based on questionnaire methods or evaluation of health records in most of the developing countries like Turkey. Therefore, serological studies are useful to appraise the impact of vaccination programmes and to improve immunization policies. This serological study was undertaken to determine the immunity status of children to poliovirus in Eastern Turkey. METHODS A cross-sectional and community-based field study was done with the sampling method of 30 clusters recommended for field studies. A total of 204 children aged 2-71 months were included. Complement fixation test was used to measure antibody titres to poliovirus serotypes. Subjects with serum antibody titres as 1:10 and lower were accepted as seronegative. A semi-structured questionnaire and official records of health care units were used to gather information about status of vaccination. RESULTS Of the 204 children included, 54.4 per cent were boys and mean age was 31.5 +/- 19.8 months; 26.5 per cent of the children were seronegative. According to official records 64.7 per cent of subjects were full vaccinated. Sensitivity and specificity of official health records were 83.6 and 67.3 per cent in relation to immunity status of children, respectively. Regarding number of OPV doses given to children, the sensitivity and specificity of parents recall in relation to official records were 98.0 and 17.4 per cent, respectively. INTERPRETATION & CONCLUSION Approximately, one of four children was determined to be seronegative. This high seronegativity brings risk to control of polio in Eastern Turkey which is at the post-elimination era since 1998. Additionally, parents recall did not provide reliable information to predict the immunity status and number of OPV doses given to children.