Epidemiology of pertussis and related factors in Tianjin city

Objective To analyze the epidemiological characteristics and related factors of pertussis in Tianjin and provide evidence for the prevention and control of pertussis. Methods The descriptive epidemiological analysis was conducted on the data of pertussis from national notifiable communicable diseases reporting system. The IgG antibody to pertussis among community population was tested quantitatively by ELISA. Results The average annual incidence of pertussis was 63.02/lakh from 1953 to 2009, the epidemic cycle was 3-5 years. Most pertussis cases occurred in spring and in summer of a year, which were mainly distributed in children. The proportion of pertussis cases in adult showed a increase trend and the proportion of pertussis cases in floating population increased too. The reported DPT vaccination rate was negatively correlated with the incidence of pertussis (r=-0.842). The seroconversion rate to pertussis antigen was 73.33% by DTaP vaccination. The positive rate of IgG against pertussis was 66.42% in 2007and 47.11% in 2009. The positive rate of IgG against pertussis in children aged7 years was lower than that in children aged7 years (P0.001). Conclusion The incidence of pertussis decreased as the expansion of vaccination coverage in Tianjin. In order to prevent the reemergence of pertussis in Tianjin, it is necessary to improve the vaccination of purtussis in eligible children, revise immunization strategy in time, strengthen the surveillance of pertussis in community and increase the reporting rate and diagnosis rate of pertussis.