Gansu in Western China

image courtesy of pixabay - user Liruoyingdoudou2009

人棘球菌 - 分布和影响
棘球菌是一种全球分布的人畜共患病，由寄生虫的幼虫阶段引起echinoccocus。

当前的W.H.O的估计suggest that globally, more than 1 million people are infected with echinococcosis, leading to approximately 871 000 disability-adjusted life-years (DALYs) each year. As well as the substantial disease burden and deaths associated with human echinococcosis, treatment of livestock infections are estimated to be over $3 billion (USD) annually.

治疗方案目前是复杂且危险的，通常需要长时间的药物治疗和/或侵入性手术。

在所有受人棘球菌影响影响的地区中国西部的患病率最高世界上的任何地方，因此对中国这个地区的公共卫生的影响是巨大的，尤其是在农村，牧民和经济弱势群体的地区。

The high endemicity of human echinococcosis in Western China has led researchers to investigate the geographical and environmental conditions of the region, and question whether specific environmental factors might influence transmission of echinococcosis to humans. For example,one studylinked the prevalence of echinococcosis with annual mean precipitation, and其他发现较高的高度与棘球菌患病率增加之间的相关性。

尽管将特定的环境因素与人棘球菌病联系起来，但迄今为止，尚无研究研究如何或是否可以预测人棘球菌风险的预测因素。

Jie Yin及其同事的最新研究来自北京的全球变化与地球系统科学学院已经开始做到这一点，并且是第一个对中国西部人类棘球菌病的空间分布进行建模和预测的人。

Creating and informing the model
为了研究人类棘球菌病的空间分布和环境风险因素，研究人员首先选择了中国西部的344个县（请参阅下面的研究图），以获取研究中的纳入县级棘突中的县级流行率数据CDCreports and epidemiological studies (surveyed) for later comparison against predictions of prevalence made by their model.

Nine environmental factors considered as natural risk factors for echinococcosis and four seasonal indices (spring, summer, autumn and winter) were chosen for the prediction, which fall into two categories, climate and geographical:

气候因素：

• Temperature (T)
• 降水（PRE）
• 相对湿度（RH）
• Sunshine duration (sun)

Geographical factors:

• Elevation (measured as digital elevation model (DEM))
• 植被密度（以归一化差异植被指数（NDVI）测量）
• Grassland area ratio (GrassR)
• 森林面积比（外衣）
• 耕地面积比（耕地）

为了分析每个县的九个环境因素与棘球发生的患病率之间的关系，并预测了人类患病率的潜在热/冷点，研究人员使用贝叶斯推断构建了结构化的加性回归（Star）数学模型。

对模型提供的人类棘球风险的见解
The predicted prevalence and hot/cold spot model for each county was generally in agreement with the prevalence and hot/cold spots reported by the surveyed findings, providing support for the constructed model.

The authors do note however, that modelled prevalence based on the environmental factors was in some instances higher than surveyed prevalence, suggesting that past control measures implemented in Western China have been effective in reducing human echinococcosis prevalence from what is possible based on the environmental conditions.

高流行地区患病率最高(>2%) were almost exclusively concentrated in the Qinghai-Tibet Plateau in South/Southwestern China. Counties outside the Plateau region generally had low predicted echinococcosis prevalence (<0.5%).

因此，这三个发现的热点也被预测位于高海拔青海地高原上，表明环境条件非常适合人类棘球菌的传播，预防和控制应集中在该地区。

Key environmental factors influencing echinococcosis transmission
The model also revealed that both climate and geographical landscape factors had a significant impact on human echinococcosis prevalence in the region.

In particular, elevation (DEM), vegetation density (NDVI) in Spring, Summer precipitation (pre) and sunshine duration (sun), relative humidity (rh) in the Winter, GrassR, and ForestR were shown to be key environmental factors.

These factors likely influence the survival, infectivity, and successful release of Echinococcus eggs into the environment, and act as drivers of parasite transmission in Western China.

Conclusion
Jie Yin和Collueages的这项工作说明了空间流行病学建模如何有助于告知现实世界疾病的预防和控制策略，并且可以帮助改善预防和控制措施的优先级，并使资源更好地分配到最需要的地方。

作者指出，人类棘球菌病的其他危险因素，例如社会经济环境，人口人群，人类行为，栖息地类型和动物感染状况，可以进一步改善该模型做出的棘球发生率预测，并促进其用于预测类似热点的使用Neglected Tropical Diseases。