GIS-based Liver Fluke Risk Forecasting System

基于GIS的肝吸虫风险预测系统

• 批准号: 104619
• 金额: $ 50.43万
• 依托单位: FARMING ONLINE LTD
• 依托单位国家: 英国
• 项目类别: Collaborative R&D
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=104619
• 关键词: GIS; based; Liver; Fluke; Risk

"The common liver fluke, _Fasciola hepatica_, is a trematode parasite affecting sheep and cattle. The lifecycle of _F hepatica_ involves an intermediate snail host; in the UK the principal species is _Galba truncatula_, the dwarf pond snail. Eggs are passed in the faeces of infected animals. Once washed out of the faeces, the eggs develop, releasing short-lived miracidia. These require water to swim through, and once they find the snail, burrow through the foot into the body cavity. The flukes multiply in the snail, and at about 6 weeks, cercariae are released, which encyst on vegetation to form infective metacercariae. Grazing livestock then eat the contaminated herbage, metacercariae hatch, and newly excysted juveniles burrow through the gut wall and migrate into the liver. In cattle it takes about 10-12 weeks for the flukes to reach the bile ducts, mature, and begin producing eggs that are subsequently deposited in faeces. The fluke lifecycle requires _G truncatula_ to be present (although other species of snail such as _Radix spp_ can support parasite development). These snails feed on algae on the surface of mud, and slow-moving bodies of water with poor drainage and a neutral or slightly acidic pH are favourable conditions. Snails are commonly found around the edges of ponds, streams, hoof-prints and tractor ruts in muddy fields. During winter, the snails go into hibernation, and development of any stages of the parasite in the snail is arrested. In spring, snails come out of hibernation and the parasite lifecycle resumes. During mild winters, fewer snails perish, so more are present in spring. The rate of egg development is dependent on temperature; above 10ºC, development takes 2--4 weeks, the warmer the weather, the faster development. Fasciolosis is a seasonal disease in the UK, although patterns have been changing in recent years. Development of the free-living and intramolluscan stages of the parasite typically occurs between May and October; with ideal weather conditions over the summer, large numbers of metacercariae are released from snails onto pastures in August to October. The number of infective cysts is dependent the climatic conditions, typically peaking in late summer and early autumn, although metacercariae can be present on pasture all year round. Thus livestock grazing at-risk pastures can become infected at any time of the year. Moreover, there is little evidence that cattle develop immunity or resistance to fluke infection, and so animals can be repeatedly infected."

“普通的肝fl虫，_fasciola hepatica_是一种影响绵羊和牛的Trematode寄生虫。动物曾经从粪便中洗净，这些卵子奇迹般的奇迹会在蜗牛中游泳。在植被上，肠道孵化，新近的少年散发出肠道并迁移到肝脏中_g truncatula_出现）蜗牛在泥浆表面的藻类上进食，并在池塘，溪流，hoof-，hoof-，hoof-的边缘周围发现了蜗牛的慢速流动物体和中性或略带酸性的pH。在泥泞的冬天，蜗牛进入蜗牛，蜗牛在蜗牛中的发育，蜗牛是蜗牛，蜗牛是从冬眠中出现的，寄生虫恢复了，蜗牛的发展。在10ºC的温度下，ER较快的发育速度是英国的一种季节性疾病，最近的自由生活和寄生虫的自由生活发生了变化夏季的理想天气，大量的MetaCeraie从蜗牛到奥古斯特的牧场都取决于气候条件此外，很少有证据表明牛会产生免疫力或抗性感染，因此可以反复感染动物。