According to the information reflected by Anhui Center for Disease Control (Anhui CDC) in Hefei, Anhui province of China, some patients infected with respiratory diseases did not seek medical treatment (nonclinic visits) due to their strong resistance, and the influence of them on the spread of respiratory diseases has not been known. A SIS model with considering the nonclinic visits was established; a qualitative theory of the model was analyzed to obtain the basic reproduction number , disease-free equilibrium, endemic equilibrium, and stability of two equilibriums. Then, the model is combined with the daily number of respiratory diseases for parameter estimation and numerical simulation. Numerical simulation results showed that respiratory diseases were easy to break out in the autumn and winter and were relatively stable in the spring and summer. Through parameter estimation, the unknown parameter value was achieved and the result was obtained that the initial number of nonclinic visits is 10-11 times that of clinic visits. Finally, the result of sensitivity analysis displayed that the proportion of the number of nonclinic visits to the total number of patients has a significant influence on the final number of patients. If persons improve their resistance so that the number of nonclinic visits increases, the total number of patients will be reduced or even reduced to zero. Besides, reducing contact infection rate of disease and increasing the cure rate can also reduce the final total number of patients.

中文翻译：

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模拟非诊所就诊对呼吸系统疾病传播的影响。

根据安徽省合肥市疾病预防控制中心（安徽省疾病预防控制中心）反映的信息，一些呼吸系统疾病患者由于抵抗力强，并受到感染的影响而没有就医（非诊所就诊）呼吸系统疾病的传播尚不清楚。建立了考虑非诊所就诊的SIS模型；分析了模型的定性理论，得到了基本繁殖数，无病平衡，地方平衡和两个平衡的稳定性。然后，将模型与每天呼吸道疾病的数量相结合，以进行参数估计和数值模拟。数值模拟结果表明，呼吸系统疾病在秋季和冬季很容易爆发，而在春季和夏季则相对稳定。通过参数估计，获得了未知的参数值，并且得到的结果是，非诊所就诊的初始次数是诊所就诊次数的10-11倍。最后，敏感性分析的结果表明，非诊所就诊次数占患者总数的比例对最终患者人数有重大影响。如果人们提高了抵抗力，从而增加了非诊所就诊的次数，患者总数将减少甚至减少到零。此外，降低疾病的接触感染率和提高治愈率也可以减少最终的患者总数。