Population dynamics of sporogony in Thailand

描述（由申请人提供）：疟疾仍然是世界上最严重的疾病之一。 世界上最严重的传染病。疟疾的传播是 取决于疟原虫寄生虫的孢子生殖发育， 蚊子孢子生殖是一个复杂的过程， 不同的生命阶段，可以用寄生虫种群来描述 动力学我们对孢子生殖的认识大多来自于实验室模型 系统.很少有研究试图在一个 严格的、定量的方式描述自然界中的孢子生殖过程。 这一建议的主要假设是：1）寄生孢子生殖更多 在现场比在实验室更有效，2）有关键的生命阶段 这些转变决定了孢子生殖成功的可能性， 矢量（即，发展瓶颈）。的大小和解剖部位 蚊子体内的这些瓶颈可能因不同的寄生虫而异 在不同的蚊子种类中发展。这项建议的目的是 使用人口动态方法来确定关键的生命阶段过渡 对恶性疟原虫和间日疟原虫的成功影响最大 土著病媒种群内的孢子生殖。实验方法将 包括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寄生虫，使用当地按蚊物种。寄生虫 在整个过程中， 孢子生殖发育和关键寄生虫生命阶段的密度（即， 配子母细胞、动合子、卵囊和子孢子）进行定量。的 生命阶段转换的相对效率（丰度的变化）和 蚊子对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。拟议的研究 将在泰国西部的一个小村庄进行。研究正在 与现有的美国军事实地研究工作和泰国合作， 公共卫生部努力了解人口 孢子生殖动态与当地疟疾流行病学相关 传输该项目是第一次长期审查 疟疾寄生虫在其自然媒介中的自然种群动态 并将有助于更好地了解疟原虫如何生存， 在野外的蚊子体内维持。

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.