Center for Infectious Disease Research, School of Biological Sciences, Pontifical Catholic University of Ecuador, Quito, Ecuador; Tropical Disease Institute, Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, Ohio, United States of America.
Center for Infectious Disease Research, School of Biological Sciences, Pontifical Catholic University of Ecuador, Quito, Ecuador.
PLoS Negl Trop Dis. 2014 Jun 26;8(6):e2960. doi: 10.1371/journal.pntd.0002960. eCollection 2014 Jun.
Chagas disease is a serious public health problem in Latin America where about ten million individuals show Trypanosoma cruzi infection. Despite significant success in controlling domiciliated triatomines, sylvatic populations frequently infest houses after insecticide treatment which hampers long term control prospects in vast geographical areas where vectorial transmission is endemic. As a key issue, the spatio-temporal dynamics of sylvatic populations is likely influenced by landscape yet evidence showing this effect is rare. The aim of this work is to examine the role of land cover changes in sylvatic triatomine ecology, based on an exhaustive field survey of pathogens, vectors, hosts, and microhabitat characteristics' dynamics.
The study was performed in agricultural landscapes of coastal Ecuador as a study model. Over one year, a spatially-randomized sampling design (490 collection points) allowed quantifying triatomine densities in natural, cultivated and domestic habitats. We also assessed infection of the bugs with trypanosomes, documented their microhabitats and potential hosts, and recorded changes in landscape characteristics. In total we collected 886 individuals, mainly represented by nymphal stages of one triatomine species Rhodnius ecuadoriensis. As main results, we found that 1) sylvatic triatomines had very high T. cruzi infection rates (71%) and 2) densities of T. cruzi-infected sylvatic triatomines varied predictably over time due to changes in land cover and occurrence of associated rodent hosts.
We propose a framework for identifying the factors affecting the yearly distribution of sylvatic T. cruzi vectors. Beyond providing key basic information for the control of human habitat colonization by sylvatic vector populations, our framework highlights the importance of both environmental and sociological factors in shaping the spatio-temporal population dynamics of triatomines. A better understanding of the dynamics of such socio-ecological systems is a crucial, yet poorly considered, issue for the long-term control of Chagas disease.
恰加斯病是拉丁美洲的一个严重公共卫生问题，约有 1000 万人感染克氏锥虫。尽管在控制家居性锥蝽方面取得了重大成功，但在杀虫剂处理后，森林种群经常侵入房屋，这阻碍了在广泛的地域范围内进行长期控制的前景，而这些地域正是该病的媒介传播流行区。作为一个关键问题，森林种群的时空动态可能受到景观的影响，但很少有证据表明存在这种影响。这项工作的目的是基于对病原体、媒介、宿主和微生境特征动态的详尽实地调查，研究土地覆盖变化对森林锥蝽生态学的作用。
该研究以厄瓜多尔沿海的农业景观为研究模型。在一年的时间里，采用空间随机抽样设计（490 个采集点），定量检测了自然、耕作和家庭生境中锥蝽的密度。我们还评估了虫子感染锥虫的情况，记录了它们的微生境和潜在宿主，并记录了景观特征的变化。总共收集了 886 只个体，主要代表一种锥蝽物种 Rhodnius ecuadoriensis 的若虫阶段。作为主要结果，我们发现：1）森林锥蝽的克氏锥虫感染率非常高（71%）；2）由于土地覆盖的变化和相关啮齿动物宿主的出现，感染 T. cruzi 的森林锥蝽的密度随时间而有规律地变化。
我们提出了一个框架，用于识别影响森林 T. cruzi 媒介年度分布的因素。除了为控制森林媒介种群对人类栖息地的殖民提供关键的基础信息外，我们的框架还强调了环境和社会学因素在塑造锥蝽时空种群动态方面的重要性。更好地了解这种社会生态系统的动态是长期控制恰加斯病的一个关键但尚未得到充分考虑的问题。
