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.
Plasmodium vivax radical cure requires the use of primaquine (PQ), a drug that induces haemolysis in glucose-6-phosphate dehydrogenase deficient (G6PDd) individuals, which further hampers malaria control efforts. The aim of this work was to study the G6PDd prevalence and variants in Latin America (LA) and the Caribbean region. A systematic search of the published literature was undertaken in August 2013. Bibliographies of manuscripts were also searched and additional references were identified. Low prevalence rates of G6PDd were documented in Argentina, Bolivia, Mexico, Peru and Uruguay, but studies from Curaçao, Ecuador, Jamaica, Saint Lucia, Suriname and Trinidad, as well as some surveys carried out in areas of Brazil, Colombia and Cuba, have shown a high prevalence (> 10%) of G6PDd. The G6PD A-202A mutation was the variant most broadly distributed across LA and was identified in 81.1% of the deficient individuals surveyed. G6PDd is a frequent phenomenon in LA, although certain Amerindian populations may not be affected, suggesting that PQ could be safely used in these specific populations. Population-wide use of PQ as part of malaria elimination strategies in LA cannot be supported unless a rapid, accurate and field-deployable G6PDd diagnostic test is made available.
Abstract. Despite the importance of mangrove ecosystems in the global carbon budget, the relationships between environmental drivers and carbon dynamics in these forests remain poorly understood. This limited understanding is partly a result of the challenges associated with in situ flux studies. Tower-based CO2 eddy covariance (EC) systems are installed in only a few mangrove forests worldwide, and the longest EC record from the Florida Everglades contains less than 9 years of observations. A primary goal of the present study was to develop a methodology to estimate canopy-scale photosynthetic light use efficiency in this forest. These tower-based observations represent a basis for associating CO2 fluxes with canopy light use properties, and thus provide the means for utilizing satellite-based reflectance data for larger scale investigations. We present a model for mangrove canopy light use efficiency utilizing the enhanced green vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) that is capable of predicting changes in mangrove forest CO2 fluxes caused by a hurricane disturbance and changes in regional environmental conditions, including temperature and salinity. Model parameters are solved for in a Bayesian framework. The model structure requires estimates of ecosystem respiration (RE), and we present the first ever tower-based estimates of mangrove forest RE derived from nighttime CO2 fluxes. Our investigation is also the first to show the effects of salinity on mangrove forest CO2 uptake, which declines 5% per each 10 parts per thousand (ppt) increase in salinity. Light use efficiency in this forest declines with increasing daily photosynthetic active radiation, which is an important departure from the assumption of constant light use efficiency typically applied in satellite-driven models. The model developed here provides a framework for estimating CO2 uptake by these forests from reflectance data and information about environmental conditions.
Deforestation in Indonesia poses a significant threat to the region's biodiversity. We mapped forest cover in Kalimantan, Indonesia, in 2002, with imagery provided by the Moderate Resolution Imaging Spectrometer (MODIS). The MODIS-based forest and nonforest map showed good agreement with other sources of recent data on forest cover. Comparison of MODIS forest cover with Indonesian government data from 1996 revealed that almost 3 million ha of forest were lost in Kalimantan since the major El Niño event of 1997-1998, when a drought produced unprecedented biomass burning in the region. Over two-thirds of the deforestation occurred in proposed and existing protected areas, especially those of 100,000-250,000 ha. The loss of forest in proposed and existing protected areas suggests that Kalimantan's protected-area network is no longer viable and that alternative conservation strategies, such as timber certification and improved monitoring and enforcement, are needed to preserve remaining forest habitats there.Pérdida de Cobertura Forestal en Kalimantan, Indonesia, desde El Niño de 1997-1998. Resumen: La deforestación en Indonesia es una amenaza significativa para la biodiversidad de la región.Mapeamos la cobertura forestal en Kalimantan, Indonesia en 2002 con imágenes proporcionadas por el espectrofotómetro de imágenes de resolución moderada (EIRM). El mapa de bosques basado en EIRM y el mapa deáreas sin bosque mostraron similitudes con otras fuentes de datos recientes sobre la cobertura forestal. La comparación de la cobertura forestal de EIRM con datos de 1996 del gobierno indonesio reveló que se perdieron casi 3 millones de ha de bosque en Kalimantan desde el importante evento de El Niño de 1997-1998 sequía importante produjo una quema de biomasa sin precedentes en la región. Más de las dos terceras partes de la deforestación ocurrieron enáreas protegidas existentes y propuestas, especialmente las de 100,000-250,000 ha. La pérdida de bosque enáreas protegidas propuestas y existentes sugiere que la red deáreas protegidas de Kalimantan ya no es viable y que se requieren estrategias alternativas de conservación, como la certificación de madera y el mejoramiento del monitoreo y la aplicación de leyes, para preservar los hábitats de bosque remanentes.
We examined the spatiotemporal patterns of fire in insular Southeast Asia from July 1996 to December 2001 using a set of consistent, nighttime fire observations provided by the Along Track Scanning Radiometer (ATSR) sensor. Monthly ATSR fire counts were analyzed relative to georeferenced climatic and land-cover data from a variety of sources. We found that fires were strongly correlated with Southern Oscillation Index (SOI) (r = −0.75) and Niño 3.4 index (r = 0.72) in forested land-cover types within the equatorial belt (5.5 • S-5.5 • N). Cross-correlation analysis revealed that detrended SOI was modestly correlated (r = 0.42) with detrended monthly fire count with a positive lag of four months. However, our analysis also revealed that fire counts reached their maximum 6 months before the absolute maximum of SOI. Annual sums of SOI ( SOI ) and fire counts revealed linearity for SOI ≤ 0. Overall, the results suggest that ENSO indices may have limited predictive utility at a monthly time scale, but that temporal aggregation and additional fire observations may enhance our capacity to forecast fires in different cover types based on ENSO data.
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