Dengue fever (DF) and dengue hemorrhagic fever (DHF) are growing health concerns throughout Latin America and the Caribbean. This study focuses on Costa Rica, which experienced over 100 000 cases of DF/DHF from 2003 to 2007. We utilized data on sea-surface temperature anomalies related to the El Niño Southern Oscillation (ENSO) and two vegetation indices derived from the Moderate Resolution Imaging Spectrometer (MODIS) from the Terra satellite to model the influence of climate and vegetation dynamics on DF/DHF cases in Costa Rica. Cross-correlations were calculated to evaluate both positive and negative lag effects on the relationships between independent variables and DF/DHF cases. The model, which utilizes a sinusoid and non-linear least squares to fit case data, was able to explain 83% of the variance in weekly DF/DHF cases when independent variables were shifted backwards in time. When the independent variables were shifted forward in time, consistently with a forecasting approach, the model explained 64% of the variance. Importantly, when five ENSO and two vegetation indices were included, the model reproduced a major DF/DHF epidemic of 2005. The unexplained variance in the model may be due to herd immunity and vector control measures, although information regarding these aspects of the disease system are generally lacking. Our analysis suggests that the model may be used to predict DF/DHF outbreaks as early as 40 weeks in advance and may also provide valuable information on the magnitude of future epidemics. In its current form it may be used to inform national vector control programs and policies regarding control measures; it is the first climate-based dengue model developed for this country and is potentially scalable to the broader region of Latin America and the Caribbean where dramatic increases in DF/DHF incidence and spread have been observed.

中文翻译：

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厄尔尼诺南方涛动和植被动态作为哥斯达黎加登革热病例的预测因子

登革热 (DF) 和登革出血热 (DHF) 是整个拉丁美洲和加勒比地区日益严重的健康问题。本研究重点关注哥斯达黎加，该国在 2003 年至 2007 年间经历了超过 100 000 例 DF/DHF。我们利用了与厄尔尼诺南方涛动 (ENSO) 相关的海面温度异常数据和源自中等分辨率的两个植被指数来自 Terra 卫星的成像光谱仪 (MODIS)，用于模拟气候和植被动态对哥斯达黎加 DF/DHF 案例的影响。计算互相关以评估对自变量与 DF/DHF 案例之间关系的正负滞后效应。该模型利用正弦曲线和非线性最小二乘法来拟合案例数据，当自变量及时向后移动时，能够解释每周 DF/DHF 案例中 83% 的方差。当自变量及时向前移动时，与预测方法一致，模型解释了 64% 的方差。重要的是，当包括五个 ENSO 和两个植被指数时，该模型再现了 2005 年主要的 DF/DHF 流行病。模型中无法解释的差异可能是由于群体免疫和病媒控制措施，尽管有关疾病系统这些方面的信息普遍缺乏。我们的分析表明，该模型最早可用于提前 40 周预测 DF/DHF 的爆发，并且还可能提供有关未来流行病严重程度的宝贵信息。以目前的形式，它可用于为国家病媒控制计划和有关控制措施的政策提供信息；这是为该国开发的第一个基于气候的登革热模型，并且有可能扩展到拉丁美洲和加勒比地区的更广泛地区，在这些地区已经观察到 DF/DHF 的发病率和传播率急剧增加。