【作者】 赵军伟；

【导师】 丁光宏；

【作者基本信息】 复旦大学 ， 流体力学， 2008， 博士

【摘要】 血吸虫病是一种以水为媒介、极大影响人们健康、社会稳定和经济发展的严重的传染病和寄生虫病。它在我国主要流行于长江流域及其以南的12个省、自治区和直辖市的381个流行县（市、区）,受血吸虫病危害的人口达1亿以上。我国结合国情,常用的控制血吸虫病疫情的方法有:人牛同步化疗和灭螺。各年的数据显示,人牛同步化疗应用更为广泛,但是这些措施持续的时间不长。近年来,我国在血吸虫病防治上面也提出了一些长效机制,例如在洲滩等地建厕所、耕牛圈养并用拖拉机代替耕牛工作。本文根据湖南湖北两省六个村落1990-1998年的实际患病率数据,以及对Barbour双宿主模型参数的理解,通过添加方程的方法,完善了Barbour双宿主模型。同时用改进以后的模型模拟了人牛同步化疗、建厕所和耕牛替代的措施实施下的人牛患病率。其中建厕所和耕牛替代这两种措施目前还没有被国内外专家用数值模拟的方法系统研究过。本文通过数值模拟和比较我们得到了这样的结论:建厕所是一种长效机制,其主要作用是控制人对于环境的污染。在其作用下,我们所选取的六个村子,双宿主传播的总的基本繁殖率R″₀均小于1,人和牛的患病率将会趋于无病平衡点。人牛同步化疗是一种短效机制,它只能短期内降低人牛的患病率。力度越高,反弹所需的时间越长。在其作用下,双宿主传播的总的基本繁殖率R″₀在我们计算的湖南湖北省的六个村落中都是大于1的,从数学意义上讲,血吸虫病将在这些村落里形成一种地方病。耕牛替代也是一种长效机制,它实施以后,对于牛的患病率控制效果尤为明显,对人的患病率控制较为一般.在耕牛替代措施下,R″₀均小于1,它将会趋于无病平衡点。它可以作为一种长效的控制措施,在其替代时间内会一直发挥作用,其效果具有持续性,长期使用可以达到消灭血吸虫病的目的。我国在血吸虫病的疫区还是实行大范围的人牛同步化疗措施的,而针对于湖南省来说,大部分地区的耕牛都是洲滩敞放的,牛的患病率比较高。牛在血吸虫病的传播因素中又比较重要,高的牛的患病率必定对疾病的控制是一个很大的威胁。在这些地区,可以先通过人牛同步化疗将人和牛的患病率降到一个较低的水平,然后适度的辅以耕牛替代这样的长效机制进一步对牛的患病率进行控制,使人牛患病率控制在国家疫情控制标准以下。综上所述,在人和牛的患病率都比较一般或较低的时候,人牛同步化疗是一个比较不错的选择;在牛的患病率比较高而人的患病率一般的时候,耕牛替代措施比较优越;在人粪阳性率对于环境污染达到一定程度的时候,建厕所措施就能体现其优势了。因此我们在实施措施的时候要因地制宜。最后笔者根据对Barbour双宿主模型参数的研究,并且根据我国血吸虫病学研究上分层的实际情况,建立了分层模型.随后针对安徽省贵池市流坡村分三线的实例,通过一些模型假设使方程组简化,利用各年份、各个分线的人的患病率以及总的牛的患病率进行计算,并得到了简要的分层模型的结论。更多还原

【Abstract】 Schistosomiasis is a serious infectious and parasitic disease transmitted through the medium of water, with great influence on human health, social stability and economic development. It mainly prevails in 381 counties (cities, districts) of 12 provinces, autonomous regions, municipalities along and to the south of the Yangtze River valley, and above 100 million people become the victims of schistosomiasis. Often two methods are taken to control epidermic situation according to the situation of our country: mass human and buffalo synchronous chemotherapy and focal snail control. Statistics by year show that mass human and buffalo synchronous chemotherapy is extensively adopted, but these measures will not be long sustained. In recent years, a number of long-term mechanism on the prevention and treatment of China’s schistosomiasis have been proposed, such as building latrines on places like sand beach, stable cattle breeding and using tractors to replace the work of farm cattle.According to the actual data of the morbidity rate in six villages of Hunan and Hubei provinces between 1990 and 1998, as well as understanding on the parameters of the Barbour’s two-host model, by the way of adding the equations, this dissertation improve the Barbour’s two-host model. At the same time, the improved simulation model is used to simulate the morbidity rate of human and buffalo under the measures of mass human and buffalo synchronous chemotherapy, building latrines and substitution for farm cattle, among which the latter two measures have not yet been systematically studied through numerical simulation by experts at home and abroad.In this article, the conclusion has been achieved through numerical simulation and comparison that:To build latrines is a long-term mechanism, whose main role is to control human environmental pollution. Under its influence, we selected six villages, while all of theoverall basic reproduction rate through the two-host transmission R_o" are less than 1,and tend to reach the disease-free equilibrium.Mass human and buffalo synchronous chemotherapy is a short-term mechanism, which can only reduce morbidity rate of human and buffalo in a short period of time. The higher the strength is, and the longer time is required to bounce back. Under its influence, all of the overall basic reproduction rate R_o" of two-host transmission inour calculation of six villages in Hunan, Hubei Provinces are more than 1. In the mathematical sense, schistosomiasis tends to be an endemic disease in these villages.Substitution for farm cattle is also a long-term mechanism, which has particularly obvious effects on the control over the morbidity rate of buffalo, while the control over the morbidity rate of human has moderate effects. By the means of substitutionfor farm cattle, all values of R_o~" are less than 1, which tend to reach the disease-freeequilibrium. It can be taken as a long-term control measure to play roles throughout the substitution periods, and the persistent effects make it possible to achieve the eradication of schistosomiasis along with long-term usage.A wide range of mass human and buffalo synchronous chemotherapy measures are still taken in China’s affected areas of schistosomiasis, while in ralation to Hunan Province, farm cattle are grazed in the wilds in most regions, the morbidity rate of buffalo is relatively higher. The buffalo plays a comparatively important role in the spreading factor of schistosomiasis, and the high morbidity rate of buffalo is a big threat to disease control. In these areas, mass human and buffalo synchronous chemotherapy can first be adopted to reduce the morbidity of human and buffalo to a lower level, and then the further control of the morbidity of buffalo can be appropriately supplemented by long-term mechanisms like substitution for farm cattle to confine the morbidity of human and buffalo to the national epidemic control standards.To sum up, when the morbidity rate of human and buffalo is relatively moderate or low, mass human and buffalo synchronous chemotherapy is a much better choice; when the morbidity of cattle is relatively high and the morbidity rate of human is moderate, substitution for farm cattle has comparatively benefits; when the positive rate of human excrement influences on environment pollution to a certain degree, the measures of building latrines can take advantages. That is why we have to take different measures in the light of local conditions. Finally, according to the author’s research on the Barbour’s two-host model parameters in accordance with the actual situation of stratification based on the study of schistosomiasis in China, a hierarchical model is constructed. Subsequently, exemplified by the instances of dividing Liupo Villige in Guichi City of Anhui Province into three lines, some assumed models are applied to simplify the equations, and calculations are made based on the morbidity rate of human in different years and on differnt lines as well as the overall morbidity rate of buffalo, then a brief hierarchical model is thus summarized.更多还原