Bordetella pertussis serological profile among asymptomatic individuals aged 4-24 years.

Abstract

INTRODUCTION AND OBJECTIVES: To determine the antibody levels against pertussis toxin to determine the need and the optimal age for booster immunization. METHODS: The quantitative determination of specific IgG antibodies to Bordetellajiertussistox'm was done by the ELISA using sera of 385 asymptomatic individuals aged 4 -24 years admitted to surgical units of Lady Ridgeway Hospital, Colombo and Colombo South Teaching Hospital, Kalubowila. Mann-Whitney U test and Kruskal-Waliis test were used in analysis and p<0.05 was taken as significant. RESULTS: Median age was 12 years {IQR 8-19) with 212 (55.1%) females. The median (1QR) anti PT antibody level was 3.31 lu/ml (0.73-15.12) and 352 (91%) had anti PT level <55 lU/ml. Median {IQR) anti PT levels were 3.18 ILJ/ml (0.591-8.00) for 4-7 years, 1.43 lU/ml (0.336-6.27) for 8-11 years, 4.28 lU/ml (0.978-13.39) for 12-15 years,6.14 lU/ml (1.44-63.25) for 16-19 years and 4.89 lU/ml (1.11-16.78) for 20-24 years and this difference was statistically significant (p=0.000). Females (p<0.003) and those having a sibling above 12 years (p=0.017) had significantly higher anti PT levels. CONCLUSIONS: The majority of the study population, especially 8 to 11 years age group had very low anti PT IgG levels. The infection may occur in early adolescents. A booster dose of acellular pertussis vaccine could be considered.