Mathematical, Computational & Modeling Sciences Center, School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona, USA.
Malar J. 2009 Jun 27;8:142. doi: 10.1186/1475-2875-8-142.
Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. Increasing the understanding of the transmission dynamics of falciparum and vivax malaria and their relationship could suggest improvements for malaria control efforts. Here the weekly number of malaria cases due to Plasmodium falciparum (1994-2006) and Plasmodium vivax (1999-2006) in Perú at different spatial scales in conjunction with associated demographic, geographic and climatological data are analysed.
Malaria periodicity patterns were analysed through wavelet spectral analysis, studied patterns of persistence as a function of community size and assessed spatial heterogeneity via the Lorenz curve and the summary Gini index.
Wavelet time series analyses identified annual cycles in the incidence of both malaria species as the dominant pattern. However, significant spatial heterogeneity was observed across jungle, mountain and coastal regions with slightly higher levels of spatial heterogeneity for P. vivax than P. falciparum. While the incidence of P. falciparum has been declining in recent years across geographic regions, P. vivax incidence has remained relatively steady in jungle and mountain regions with a slight decline in coastal regions. Factors that may be contributing to this decline are discussed. The time series of both malaria species were significantly synchronized in coastal (rho = 0.9, P < 0.0001) and jungle regions (rho = 0.76, P < 0.0001) but not in mountain regions. Community size was significantly associated with malaria persistence due to both species in jungle regions, but not in coastal and mountain regions.
Overall, findings highlight the importance of highly refined spatial and temporal data on malaria incidence together with demographic and geographic information in improving the understanding of malaria persistence patterns associated with multiple malaria species in human populations, impact of interventions, detection of heterogeneity and generation of hypotheses.
疟疾每年在全球造成约 100 万人死亡，尽管它是可预防和可治愈的。增加对恶性疟原虫和间日疟原虫传播动态及其关系的理解，可以为疟疾控制工作提出改进建议。在这里，结合相关人口、地理和气候数据，分析了秘鲁不同空间尺度上 1994-2006 年恶性疟原虫（Plasmodium falciparum）和 1999-2006 年间日疟原虫（Plasmodium vivax）每周疟疾病例数。
通过小波谱分析分析了疟疾周期性模式，研究了作为社区规模函数的持久性模式，并通过洛伦兹曲线和综合基尼指数评估了空间异质性。
小波时间序列分析确定了这两种疟疾的发病率均存在年度周期，这是主要模式。然而，在丛林、山区和沿海地区观察到显著的空间异质性，间日疟原虫的空间异质性略高于恶性疟原虫。虽然近年来，恶性疟原虫的发病率在各地区都有所下降，但在丛林和山区，间日疟原虫的发病率仍然相对稳定，而在沿海地区则略有下降。讨论了可能导致这种下降的因素。两种疟疾的时间序列在沿海地区（rho = 0.9，P < 0.0001）和丛林地区（rho = 0.76，P < 0.0001）显著同步，但在山区没有同步。在丛林地区，两种疟疾的发病率都与社区规模显著相关，但在沿海和山区则没有。
总的来说，研究结果强调了高度精细化的疟疾发病率时空数据以及人口、地理信息对改善对与多种疟疾相关的疟疾持续模式的理解的重要性，包括干预措施的影响、异质性的检测和假说的产生。
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