Population dynamics of sporogony in Thailand

描述(由申请人提供)：疟疾仍然是最严重的 世界上最重要的传染病。疟疾的传播是 取决于体内疟原虫的孢子体发育 蚊子。孢子生殖是一个复杂的过程，涉及到几个形态上的 不同的生命阶段，可以用寄生虫种群来描述 动力学。我们关于孢子体形成的大部分知识来自于实验室模型 系统。很少有研究试图在一个 严格、定量地描述自然界中发生的孢子体形成过程。 这一建议的主要假设是：1)寄生虫的孢子体形成 在现场比在实验室更有效率和2)有关键的生命阶段 决定孢子体成功的概率的转变 媒介(即发展瓶颈)。移植物的大小和解剖位置 蚊子体内的这些瓶颈对于不同的寄生虫可能是不同的。 在不同的蚊子物种中发育。这项建议的目的是 使用种群动力学方法来确定关键的生命阶段转变 对恶性疟原虫和间日疟原虫的成功影响最大 土著媒介种群内的孢子体形成。试验性的方法将 涉及控制蚊子感染自然产生的疟原虫 恶性疟原虫和间日疟原虫，使用当地按蚊物种。寄生虫 在受感染的蚊子中生长的种群将在整个过程中进行采样 孢子体发育和关键寄生虫生活期的密度(即， 将对配子体、卵母细胞、卵囊和子孢子)进行量化。这个 生命阶段转变的相对效率(丰度变化)和 蚊子感染易感性的异质性程度(频率 (分布)将在蚊子感染之间进行比较。建议进行的研究 将在泰国西部的一个小村庄进行。研究正在进行中 与现有的美国军事实地研究工作和泰国 卫生部努力了解人口是如何 产孢子体动态与当地疟疾流行病学相关 变速箱。这一项目是对 疟疾寄生虫在其自然媒介内的自然种群动态 并将有助于更好地了解疟原虫如何生存和 是在野外蚊子体内维持的。

DESCRIPTION (provided by the applicant): Malaria remains one of the most important infectious diseases in the world. Transmission of malaria is contingent on the sporogonic development of Plasmodium parasites within mosquitoes. Sporogony is a complex process involving several morphologically distinct life stages and can be described in terms of parasite population dynamics. Most of our knowledge about sporogony comes from laboratory model systems. There are very few studies that have attempted to examine in a rigorous, quantitative fashion the process of sporogony as it occurs in nature. The major hypotheses of this proposal are that 1) parasite sporogony is more efficient in the field than in the laboratory and 2) there are key life stage transitions that determine the probability of sporogonic success within the vector (i.e., developmental bottlenecks). The magnitude and anatomical site of these bottlenecks within the mosquito may differ for different parasites developing in different mosquito species. The objective of this proposal is to use a population dynamics approach to identify the key life stage transitions that most strongly influence the success of Plasmodium falciparum and P. vivax sporogony within indigenous vector populations. The experimental approach will involve controlled mosquito infections with naturally occurring Plasmodium falciparum and P. vivax parasites, using local anopheline species. The parasite populations developing within infected mosquitoes will be sampled throughout sporogonic development and the densities of key parasite life stages (i.e., gametocytes, ookinetes, oocysts and sporozoites) will be quantified. The relative efficiencies of life stage transitions (changes in abundance) and the degree of heterogeneity in mosquito susceptibility to infection (frequency distributions) will be compared among mosquito infections. The proposed studies will be conducted in a small village in western Thailand. Studies are in collaboration with existing U.S. military field research efforts and the Thai Ministry of Public Health in an effort to understand how the population dynamics of sporogony correlate to the epidemiology of local malaria transmission. This project represents the first long-term examination of the natural population dynamics of malaria parasites within their natural vectors and will lead to a better understanding of how plasmodial parasites survive and are maintained within mosquitoes in the field.