[Evaluation of Pertussis Antibody Levels (Anti-PT IgG-Anti-FHA IgG) and Associated Factors in Maternal and Cord Blood].

Abstract

Pertussis has a very high mortality and morbidity rate in early infancy. There are many strategies to protect babies from pertussis, maternal immunization is one of them. In this study, it was aimed to evaluate pertussis toxin immunoglobulin G (anti-PT IgG) and filamentous hemagglutinin immunoglobulin G (anti-FHA IgG) levels of pertussis antibody in maternal and cord blood samples and also to evaluate the factors that may be associated with maternal antibody positivity. This descriptive study was conducted between 1 July and 31 October 2020. In the study, anti PT IgG and anti-FHA IgG levels were investigated by enzyme-linked immunosorbent assay (ELISA) method in 154 maternal and 154 cord blood samples. Microbiological analyzes were performed in Hacettepe University Faculty of Medicine Central Laboratory and results of 10 IU/mL and above were considered positive. Factors that could affect antibody positivity were questioned with the data collection form. "Package for Social Sciences (SPSS)" package program version 25.0 was used for statistical analysis of the data. Chi-square and Fisher's exact tests were used for statistical analysis of categorical variables. Continuous numerical variables were analyzed with the Pearson correlation test. Logistic regression analysis was used to evaluate the factors affecting positivity. The natural logarithm of the continuous variables was taken to ensure their conformity to the normal distribution, and conformity to the normal distribution was evaluated with the Kolmogorov-Smirnov test. The results were presented at a 95% confidence interval, at a significance level of p<0.05. The mean age of the mothers included in the study was 30. Of newborn babies, 52.6% were girls and 98.7% had normal birth weights. Of deliveries, 95.5% were term and 82.5% were cesarean section. Anti-PT IgG positivity and anti-FHA IgG positivity in maternal blood were 18.8% and 48.1%, respectively. Anti-PT IgG and anti-FHA IgG positivity in cord blood samples were 38.3% and 55.8%, respectively. Anti-PT IgG positivity was 2.6 times higher in mothers who had healthcare worker relatives compared to those who did not. Anti-FHA IgG positivity was 3.2 times higher in mothers aged 25 and younger than in mothers aged 26- 35. In addition, mothers aged 36 and over were 4.4 times more anti-FHA IgG positive than the mothers aged 26-35. Anti-FHA IgG antibody positivity was found 7.3 times more in those living in extended families than those living in nuclear families. Anti-PT IgG and anti-FHA IgG levels in maternal and cord blood samples were highly positively correlated. Mothers in the study had low pertussis antibody levels, indicating that newborns are at risk for infection. Maternal immunization with pertussis-containing vaccine is the most appropriate and cost-effective strategy to protect the newborn against pertussis. Many countries have been using pertussis-containing vaccines in maternal immunization safely for many years. Replacing the tetanus-diphtheria vaccine (Td), which is included in the routine pregnancy immunization program in Türkiye, with tetanus-diphtheria-pertussis (Tdap) may be appropriate to protect the mother and newborns from pertussis infection.