基于SEIR-SEI模型长沙市输入性疟疾再传播风险预测

目的 模拟不同干预措施下长沙市输入性疟疾的疫情走向，评估不同干预措施的效果，为下一步防控提供科学依据。方法 建立输入性疫情和蚊媒数据库，根据疟疾的疾病自然史构建SEIR-SEI模型，通过改变参数来模拟不同干预措施的效果。结果 长沙市输入性疟疾疫情持续存在，以恶性疟最多［233例（58.0%）］，蚊媒以中华按蚊为主；发病人群主要为男性、年龄18～44岁者、农民工；病例最多的地区为浏阳市，输入国主要为非洲国家；单一干预下，叮咬率（θ）保持在0.01或蚊虫密度（k）保持在0.001以下时，疫情不发生再传播，缩短患者发病-确诊时间（1/γh）的效果优于只控制蚊虫叮咬率或蚊虫密度；实施综合干预的防控效果较单一干预明显提高，实施综合干预的防控效果较单一干预明显提高，当k≤1时，,θ≤0.3,1/γh≤7或者θ≤0.5，1/γh≤3时，疫情不会发生再传播风险；当k≤0.5时，θ≤0.5,1/γh≤7时，疫情也不会出现再传播风险。结论 长沙市时刻存在因输入性病例引发继发传播对潜在威胁，当出现输入性疟疾时，应采取灭蚊、防蚊、缩短发病-确诊时间等综合干预措施，将k控制0.5以下，θ控制在0.5以下，1/γh控制在7天以下最好。

Risk prediction of imported malaria re-transmission in Changsha based on SEIR-SEI model

Objective To simulate the epidemic trend of imported malaria in Changsha city under different intervention measures, to evaluate the effect of different intervention measures, and to provide scientific basis for further prevention and control. Methods The database of imported epidemic situation and mosquito vector was established, and the SEIR-SEI model was constructed according to the natural history of malaria. The effects of different intervention measures were simulated by changing parameters. Results The epidemic situation of imported malaria persisted in our city, with the largest number of falciparum malaria [233(58.0%)], and the mosquito vector was mainly Anopheles sinensis.The affected population was mainly male, aged 18 to 44 years old, and migrant workers.The area with the largest number of cases was Liuyang city, and the importing countries were mainly African countries. Under single intervention, when the bite rate(θ) was kept at 0.01 or the mosquito density(k) was less than 0.001, the epidemic did not spread again, and the effect of shortening the time of onset and diagnosis(1/γh) was better than that of only controlling mosquito bite rate or mosquito density. The prevention and control effect of comprehensive intervention was significantly higher than that of single intervention.When k≤1,θ≤0.3,1/γh≤7 or θ≤0.5, 1/γh≤3,the risk of retransmission will not occur.When k ≤0.5, θ≤0.5,1/γh≤7, the risk of retransmission will not occur either.Conclusion There is always a potential threat to secondary transmission caused by imported cases in our city. When imported malaria occurs, comprehensive intervention measures such as killing mosquitoes, preventing mosquitoes and shortening the time of onset and diagnosis should be taken. It is best to control k below 0.5, θ below 0.3 and 1/γhless than 7 days.