Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Lower Saxony, Germany.
Institute for Parasitology, Centre for Infection Medicine, University of Veterinary Medicine Hannover, Hannover, Lower Saxony, Germany.
PLoS One. 2018 Apr 9;13(4):e0195584. doi: 10.1371/journal.pone.0195584. eCollection 2018.
Understanding determinants shaping infection risk of endangered wildlife is a major topic in conservation medicine. The proboscis monkey, Nasalis larvatus, an endemic primate flagship species for conservation in Borneo, is endangered through habitat loss, but can still be found in riparian lowland and mangrove forests, and in some protected areas. To assess socioecological and anthropogenic influence on intestinal helminth infections in N. larvatus, 724 fecal samples of harem and bachelor groups, varying in size and the number of juveniles, were collected between June and October 2012 from two study sites in Malaysian Borneo: 634 samples were obtained from groups inhabiting the Lower Kinabatangan Wildlife Sanctuary (LKWS), 90 samples were collected from groups of the Labuk Bay Proboscis Monkey Sanctuary (LBPMS), where monkeys are fed on stationary feeding platforms. Parasite risk was quantified by intestinal helminth prevalence, host parasite species richness (PSR), and eggs per gram feces (epg). Generalized linear mixed effect models were applied to explore whether study site, group type, group size, the number of juveniles per group, and sampling month predict parasite risk. At the LBPMS, prevalence and epg of Trichuris spp., strongylids, and Strongyloides spp. but not Ascaris spp., as well as host PSR were significantly elevated. Only for Strongyloides spp., prevalence showed significant changes between months; at both sites, the beginning rainy season with increased precipitation was linked to higher prevalence, suggesting the external life cycle of Strongyloides spp. to benefit from humidity. Higher prevalence, epgs, and PSR within the LBPMS suggest that anthropogenic factors shape host infection risk more than socioecological factors, most likely via higher re-infection rates and chronic stress. Noninvasive measurement of fecal parasite stages is an important tool for assessing transmission dynamics and infection risks for endangered tropical wildlife. Findings will contribute to healthcare management in nature and in anthropogenically managed environments.
了解塑造濒危野生动物感染风险的决定因素是保护医学的一个主要课题。长鼻猴（Nasalis larvatus）是婆罗洲特有的旗舰保护灵长类物种，由于栖息地丧失而濒危，但仍可在河岸低地和红树林以及一些保护区中找到。为了评估社会生态和人为因素对长鼻猴肠道寄生虫感染的影响，我们于 2012 年 6 月至 10 月间在婆罗洲的两个研究地点收集了 724 份长鼻猴的粪便样本，包括后宫和单身雄性群体的样本，其大小和幼猴数量各不相同：634 份样本来自下京那巴当岸野生动物保护区（LKWS）的群体，90 份样本来自拉布克湾长鼻猴保护区（LBPMS）的群体，后者的猴子在固定的喂食台上进食。通过肠道寄生虫的流行率、宿主寄生虫物种丰富度（PSR）和每克粪便中的卵（epg）来量化寄生虫风险。应用广义线性混合效应模型来探讨研究地点、群体类型、群体大小、每个群体的幼猴数量和采样月份是否可以预测寄生虫风险。在 LBPMS，Trichuris spp.、Strongylida 和 Strongyloides spp.的流行率和 epg 以及宿主 PSR 显著升高。只有 Strongyloides spp.的流行率在月份之间有显著变化；在两个地点，降雨增加的开始雨季与更高的流行率相关，表明 Strongyloides spp.的外部生命周期受益于湿度。LBPMS 内更高的流行率、epg 和 PSR 表明，人为因素比社会生态因素更能塑造宿主的感染风险，这很可能是通过更高的再感染率和慢性压力造成的。非侵入性粪便寄生虫阶段的测量是评估濒危热带野生动物传播动态和感染风险的重要工具。这些发现将有助于自然环境和人为管理环境中的医疗保健管理。
