Population genetics of parasitic nematodes of livestock; the spread of anthelmentic resistance and range expansion in Haemonchus spp

寄生蛔虫（线虫）是人类和动物疾病的重要病原体。这种感染在全世界的牲畜（牛、绵羊和山羊）中普遍存在，是对农业最重要的经济疾病之一。据估计，它们每年给北美养牛业造成的损失超过20亿美元。蛔虫的控制依赖于用药物（驱虫药）对牲畜进行常规治疗，但许多蛔虫寄生虫现在对这些药物具有耐药性，使控制变得越来越困难。这个项目的重点是一组被称为Haemonchus的牲畜寄生虫。有许多不同种类的血蜱生活在以血液为食的牲畜胃中，并引起贫血。这些寄生虫起源于非洲，但随着牲畜迁徙而传播到世界各地，尽管最初适应于热带地区，但它们现在正在向更多的北纬地区传播，包括加拿大、西欧和斯堪的纳维亚半岛。该项目将开发基于DNA的测试来检测和识别这些寄生虫。这些工具将用于确定在世界不同地区和不同情况下，在牛、绵羊、山羊和野生动物中哪些血蜱物种最为重要。除了在热带地区研究这些寄生虫外，我们还将调查寄生虫在加拿大通过牲畜和野生动物传播的情况。我们还将使用基于DNA的技术，通过检测寄生虫DNA中的突变来检测耐药寄生虫，这些突变使寄生虫对一类重要药物产生耐药性。我们将研究这些赋予抗性的突变如何在寄生虫种群之间传播。一个特别令人担忧的风险是这些突变可能从一种寄生虫传播到另一种寄生虫。这在牲畜中是一个特别令人担忧的问题，因为耐药性在绵羊和山羊寄生虫中极为常见，但直到现在才在牛寄生虫中出现。因此，我们将调查羊和牛寄生虫之间是否存在耐药性传播。该项目将提供控制耐药性发展和防止寄生虫进入新的地区和野生动物种群所需的重要信息。

Parasitic roundworms (nematodes) are important agents of disease in both humans and animals. Such infections are ubiquitous in livestock (cattle, sheep and goats) worldwide and are amongst the most economically important diseases to agriculture. It has been estimated they cost the North American cattle industry more than $2 billion per year. Roundworm control is dependent upon the routine treatment of livestock with drugs (anthelmintics) but many roundworm parasites are now resistant to these drugs making control increasingly difficult.This project focuses on a group of livestock parasites called Haemonchus.There are a number of different species of Haemonchus that live in the stomach of livestock feeding on blood and causing anaemia. These parasites originated in Africa but have spread around the world with livestock movement and, although originally adapted to the tropics, they are now spreading to more northern latitudes including Canada, Western Europe and Scandanavia. This project will develop DNA based tests to detect and identify these parasites. These tools will be used to determine which Haemonchus species are most important in cattle, sheep, goats and wildlife in different regions of the world and in different situations.As well as studying these parasites in tropical regions, we will investigate the spread of the parasite through livestock and wildlife in Canada.We will also use DNA-based techniques to detect drug resistant parasites by detecting mutations in the parasite's DNA that confer resistance to an important class of drugs. We will study how these resistance-conferring mutations are spread between parasite populations. One particular concern is the risk that these mutations could spread from one parasite species to another. This is a particular worry in livestock because drug resistance is extremely common in sheep and goat parasites but is only now emerging in cattle parasites. Consequently we will investigate whether there is spread of drug resistance between sheep and cattle parasites. This project will provide important information needed to control the development of drug resistance and prevent the movement of parasites into new regions and wildlife populations.