Objective  To analyze the epidemiological characteristics in Dali Bai Autonomous Prefecture, Yunnan province from 2018 to 2024, so as to provide a scientific basis for formulating effective prevention and control measures in the future.

Methods Descriptive epidemiological methods were used to collate, describe, and statistically analyze the reported pertussis case data from 2018 to 2024 in Dali Prefecture, collected from the China Disease Prevention and Control Information System and the Yunnan Provincial Immunization Program Information System.

Results From 2018 to 2024, a total of 387 pertussis cases were reported in Dali Prefecture, with an average annual incidence rate of 1.65/100000. The incidence showed a continuous upward trend starting from 2021, rising rapidly to 10.41/100000 in 2024 (Linear trend χ²=602.375, P<0.001). Cases were distributed across all 12 counties (cities) in the prefecture, with Binchuan county (44.96%) and Xiangyun county (25.06%) ranking the top two. Summer and autumn were the high-incidence seasons, primarily showing a bimodal distribution with “summer peak followed by autumn peak”. The age distribution was mainly 6−<9 years old (35.14%), −<6years old (21.19%), and 9−<15years old (21.19%). The majority of cases were students (47.03%) and scattered children (23.77%). The proportion of cases under 18 years old who did not complete the immunization schedule decreased with age; 94.51% of the 4~18 year old group received ≥ 4 doses of diphtheria,tetanus and acellular pertussis combined vaccine (DTaP) vaccination. In the 0−<4years age group, the proportion with 0 doses of DTaP vaccination history was the highest at 51.72%, and within this group, 66.67% were 3−<6 months old. The coverage of pertussis nucleic acid testing projects implemented by medical institutions in Dali Prefecture was 29.27%.

Conclusion In recent years, pertussis incidence in Dali Prefecture has risen substantially, featuring regional clustering, seasonal bimodality, and predominance in school-age children. Key contributors to this upward trend include delayed vaccination in eligible children, inadequate diagnostic capacity of medical institutions, and natural attenuation of vaccine-induced antibody levels. To address this issue, priority should be given to ensuring timely completion of full-dose DTaP immunization in children under 3 years, expanding booster vaccination coverage in school-age populations, and upgrading pertussis detection techniques. Additionally, routine surveillance needs to be strengthened and complemented with pertussis seroepidemiological investigations.