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目的介绍混沌分析方法在研究疾病流行过程中的应用，并对辽宁省本溪市１９５５～１９９６年的百日咳逐月发病数进行分析。方法利用混沌动力学相空间重构技术，给出某种疾病月发病数Ｘｔ的时间趋势图、混沌相图和递次振幅图，通过递次振幅图的分布特点及谱分析，确定某种疾病流行的动力系统是否混沌，对呈混沌流行的疾病求其关联分维，判定其混沌程度。结果辽宁省本溪市１９５５～１９９６年的百日咳流行是混沌的，动力性态符合一个受噪声摄动的高－低４年循环，逐月发病数Ｘｔ具有混沌分布的迭代模型。本溪百日咳流行过程奇怪吸引子的分维值为２．６６７，其中计划免疫前分维值为２．７２２，计划免疫后分维值降为１．９３８，说明百日咳流行过程中相空间轨迹存在有规则周期性或向平稳状态发展的趋势。结论以上分析计算为疾病流行过程中非随机的一类动力系统的研究提供了新方法
Objective To introduce the application of chaos analysis method in the study of the epidemic process, and analyze the monthly incidence of pertussis in Benxi City from 1955 to 1996 in Liaoning Province. Methods The phase space reconstruction technique of chaotic dynamics was used to give the time trend graph, the chaotic phase diagram and the recurrence amplitude map of the Xt of a disease, and the disease was determined by the distribution characteristics and spectral analysis of successive amplitude images. Whether the popular dynamic system is chaotic or not, the chaotic epidemic disease needs to be correlated with its fractal dimension, and its degree of chaos is determined. Results The pertussis epidemic in Benxi, Liaoning, was chaotic during 1955-1996. The dynamic state was consistent with a high-low 4-year cycle that was perturbed by noise. The monthly incidence Xt had an iterative model of chaotic distribution. The fractal dimension of strange attractors during the epidemic process of pertussis in Benxi was 2.667, of which the pre-immune dimension value was 2.722. After planned immunization, the fractal dimension was reduced to 1.938, indicating that phase space trajectories existed during pertussis epidemics. The tendency of the rules to be cyclical or to a steady state. Conclusion The above analysis provides a new method for the study of a non-random type of dynamic system in the epidemic process.