The dynamics of helminth infection in African elephant populations are poorly known. We examined the effects of age, sex, social structure and the normalized difference vegetation index (NDVI) as primary drivers of infection patterns within and between elephant populations. Coprological methods were used to identify helminths and determine infection patterns in distinct elephant populations in Maasai Mara National Reserve, Tsavo East National Park, Amboseli National Park and Laikipia-Samburu Ecosystem. Gaussian finite mixture cluster analyses of egg dimensions were used to classify helminth eggs according to genera. Generalized linear models (GLM) and Chi-square analyses were used to test for variation in helminth infection patterns and to identify drivers in elephant populations. Helminth prevalence varied significantly between the studied populations. Nematode prevalence (96.3%) was over twice as high as that of trematodes (39.1%) in elephants. Trematode prevalence but not nematode prevalence varied between populations. Although we found no associations between helminth infection and elephant social groups (male vs family groups), the median helminth egg output (eggs per gram, epg) did vary between social groups: family groups had significantly higher median epg than solitary males or males in bachelor groups. Young males in mixed sex family groups had lower epg than females when controlling for population and age; these differences, however, were not statistically significant. The average NDVI over a three-month period varied between study locations. Cluster analyses based on egg measurements revealed the presence of Protofasciola sp., Brumptia sp., Murshidia sp., Quilonia sp. and Mammomonogamus sp. GLM analyses showed that the mean epg was positively influenced by a three-month cumulative mean NDVI and by social group; female social groups had higher epg than male groups. GLM analyses also revealed that epg varied between elephant populations: Samburu-Laikipia elephants had a higher and Tsavo elephants a lower epg than Amboseli elephants. Elephants had infection patterns characterized by within- and between-population variation in prevalence and worm burden. Sociality and NDVI were the major drivers of epg but not of helminth prevalence. Gastrointestinal parasites can have a negative impact on the health of wild elephants, especially during resource scarcity. Thus, our results will be important when deciding intervention strategies.

中文翻译：

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肯尼亚大象种群中蠕虫感染的方式

非洲象种群中蠕虫感染的动态还鲜为人知。我们检查了年龄，性别，社会结构和归一化植被指数（NDVI）作为大象种群内部和种群之间感染模式的主要驱动因素。在马赛马拉国家野生动植物保护区，东察沃国家公园，安博塞利国家公园和莱基皮亚-桑布鲁生态系统中，使用Coprological方法来识别蠕虫并确定不同大象种群中的感染模式。卵尺寸的高斯有限混合聚类分析用于根据属对蠕虫卵进行分类。使用广义线性模型（GLM）和卡方分析来测试蠕虫感染模式的变化并确定大象种群的驱动因素。在研究人群之间，蠕虫患病率差异很大。大象中线虫的患病率（96.3％）是吸虫的两倍（39.1％）。吸虫的患病率，但线虫的患病率在人群之间不尽相同。尽管我们发现蠕虫感染与大象社会群体（男性与家庭群体）之间没有关联，但是在各个社会群体之间，中位数的蠕虫卵产量（蛋/克，epg）的确存在差异：与单独的男性或男性相比，家庭群体的平均epg显着更高学士团体。在控制人口和年龄时，混合性别家庭组的年轻男性的epg低于女性。但是，这些差异在统计上并不显着。三个月的平均NDVI在研究地点之间有所不同。基于卵的测量结果进行的聚类分析表明存在Protofasciola sp。，Brumptia sp。，Murshidia sp。，Quilonia sp.。和Mammomonogamus sp。GLM分析显示，平均epg受到三个月累积平均NDVI和社会群体的积极影响；女性社会群体的EPG高于男性群体。GLM分析还显示，大象种群之间的epg有所不同：Samburu-Laikipia大象的epg比Amboseli大象的epg高，而Tsavo大象的大象的epg较低。大象的感染方式具有种群内和种群间流行率和蠕虫负担变化的特征。社交和NDVI是epg的主要驱动力，但不是蠕虫流行的主要驱动力。胃肠道寄生虫会对野生象的健康产生负面影响，尤其是在资源短缺期间。从而，