[A correlation study on pertussis antibody levels of community population and reported incidence rate in Shandong Province].

Objective

To investigate the seroepidemiological characteristics of pertussis in community populations in Shandong Province and evaluate its correlation with reported incidence from the China Disease Prevention and Control Information System.

Methods

From November to December 2024, two cities were selected from the eastern, central, and western regions of Shandong Province as study sites. A stratified random sampling method was adopted to recruit community populations across six age groups (<3 years, 3-5 years, 6-12 years, 13-16 years, 17-19 years,≥20 years). Serum levels of pertussis toxin IgG (PT-IgG) antibodies were quantitatively detected using indirect enzyme-linked immunosorbent assay (ELISA), and the relationship between antibody levels and pertussis reported incidence was analyzed.

Results

A total of 1 882 participants were included, with a recent infection rate of 4.41% (95%CI: 3.48%-5.34%). The infection rate was highest in males (5.37%, 95%CI: 3.94%-6.81%) than in females (3.43%, 95%CI: 2.26%-4.60%) (χ2=4.219, P=0.040). No significant difference was observed between urban (4.60%, 95%CI: 3.26%-5.94%) and rural communities (4.22%, 95%CI: 2.94%-5.50%) (χ2=0.157, P=0.692). Reported incidence rates across cities showed a strong linear correlation with monitored recent infection rates (r=0.858, P=0.029). The estimated infection rate (/100 000) was highest in the central region (33 452.53, 95%CI: 29 329.16-37 575.90) and lowest in the eastern region (15 979.70, 95%CI: 12 790.15-19 169.24). The recent infection rate differed significantly among age groups (χ2=20.574, P<0.001), with the highest rate in the 6-12 years group (7.21%, 95%CI: 4.43%-9.98%) and the lowest in the 17-19 years group (1.31%, 95%CI: 0.03%-2.58%). The ratio of estimated infection rate to reported incidence rate was smallest in the 3-5 age group (213.96-fold) and largest in the≥20 age group (27 798.21-fold).

Conclusion

The reported incidence trend of pertussis across different regions in Shandong Province is consistent with its seroepidemiological trend among the community population, while the actual disease burden is likely to be severely underestimated.