141 research outputs found
Surveillance of dengue fever virus: A review of epidemiological models and early warning systems
No full textDengue fever affects over a 100 million people annually hence is one of the world's most important vector-borne diseases. The transmission area of this disease continues to expand due to many direct and indirect factors linked to urban sprawl, increased travel and global warming. Current preventative measures include mosquito control programs, yet due to the complex nature of the disease and the increased importation risk along with the lack of efficient prophylactic measures, successful disease control and elimination is not realistic in the foreseeable future. Epidemiological models attempt to predict future outbreaks using information on the risk factors of the disease. Through a systematic literature review, this paper aims at analyzing the different modeling methods and their outputs in terms of acting as an early warning system. We found that many previous studies have not sufficiently accounted for the spatio-temporal features of the disease in the modeling process. Yet with advances in technology, the ability to incorporate such information as well as the socio-environmental aspect allowed for its use as an early warning system, albeit limited geographically to a local scale
Rift Valley Fever Prediction and Risk Mapping: 2014-2015 Season
No full textExtremes in either direction (+-) of precipitation temperature have significant implications for disease vectors and pathogen emergence and spread Magnitude of ENSO influence on precipitation temperature cannot be currently predicted rely on average history and patterns. Timing of event and emergence disease can be exploited (GAP) in to undertake vector control and preparedness measures. Currently - no risk for ecologically-coupled RVFV activity however we need to be vigilant during the coming fall season due the ongoing buildup of energy in the central Pacific Ocean. Potential for the dual-use of the RVF Monitor system for other VBDs Need to invest in early ground surveillance and the use of rapid field diagnostic capabilities for vector identification and virus isolation
Midwest agriculture and ENSO: A comparison of AVHRR NDVI3g data and crop yields in the United States Corn Belt from 1982 to 2014
No full textReview of NASA Earth Observations, Recent Science, and Practical Applications
No full textFreely available government satellite observations enable scientists to monitor changes across the Earth system. Calibrated and validated global satellite data have advanced our understanding of interactions within and between the energy, carbon, and water cycles. In addition to answering fundamental science questions, these environmental indicators are also used to inform practical decisions relevant to agriculture, health, renewable energy, infrastructure, and more. Assimilating satellite observations into models fills data gaps and provides predictive tools. Partnering with other organizations to reach new communities and combining environmental data with sector-specific data increases its utility and societal benefit. Additionally, under the principles of open science, government agencies are working together to make useful information derived from global observations, both data and software tools, more easily accessible. This paper reviews recent NASA Earth satellite missions, highlights a few examples of science discoveries and practical applications, and describes new activities and directions.Funding from the NASA Applied Sciences Health and Air Quality Program and Water Resources Program, as well as support by the NASA Goddard Earth Sciences Division is gratefully acknowledged. This review was inspired by the invitation to present at the ASPRS Mid-South Regional Conference at the Oak Ridge National Laboratory in 2024. The conclusions shared here are those of the authors at the time of writing and do not necessarily represent the official position of the National Aeronautics and Space Administration.https://www.ingentaconnect.com/content/asprs/pers/pre-prints/content-25-00010
Historical Perspectives on AVHRR NDVI and Vegetation Drought Monitoring
No full textNo abstract availabl
Epidemiologic and Environmental Risk Factors of Rift Valley Fever in Southern Africa from 2008 to 2011
No full textBackground: Rift Valley fever (RVF) outbreaks have been associated with periods of widespread and above-normal rainfall over several months. Knowledge on the environmental factors influencing disease transmission dynamics has provided the basis for developing models to predict RVF outbreaks in Africa. From 2008 to 2011, South Africa experienced the worst wave of RVF outbreaks in almost 40 years. We investigated rainfall-associated environmental factors in southern Africa preceding these outbreaks. Methods: RVF epizootic records obtained from the World Animal Health Information Database (WAHID), documenting livestock species affected, location, and time, were analyzed. Environmental variables including rainfall and satellite-derived normalized difference vegetation index (NDVI) data were collected and assessed in outbreak regions to understand the underlying drivers of the outbreaks. Results: The predominant domestic vertebrate species affected in 2008 and 2009 were cattle, when outbreaks were concentrated in the eastern provinces of South Africa. In 2010 and 2011, outbreaks occurred in the interior and southern provinces affecting over 16,000 sheep. The highest number of cases occurred between January and April but epidemics occurred in different regions every year, moving from the northeast of South Africa toward the southwest with each progressing year. The outbreaks showed a pattern of increased rainfall preceding epizootics ranging from 9 to 152 days; however, NDVI and rainfall were less correlated with the start of the outbreaks than has been observed in eastern Africa. Conclusions: Analyses of the multiyear RVF outbreaks of 2008 to 2011 in South Africa indicated that rainfall, NDVI, and other environmental and geographical factors, such as land use, drainage, and topography, play a role in disease emergence. Current and future investigations into these factors will be able to contribute to improving spatial accuracy of models to map risk areas, allowing adequate time for preparation and prevention before an outbreak occurs. Key Words: Rift Valley fever—Southern Africa—Environmental factors—Geographic factors—Normalized difference vegetation index data
Teleconnections and Interannual Transitions as Observed in African Vegetation: 2015–2017
No full textEl Niño/Southern Oscillation (ENSO) teleconnections present a hemispheric dipole pattern in both rainfall and vegetation between eastern and southern Africa. We analyze precipitation and normalized difference vegetation index (NDVI) departures during the 2015–2017 ENSO cycle; with one of the strongest warm events (El Niño) on record followed by a short and weak cold event (La Niña). Typically, southern (eastern) Africa is associated with dry (wet) conditions during El Niño, and wet (dry) conditions during La Niña. In general, the temporal and spatial evolution of vegetation responses show the expected dipole pattern during the 2015–2016 El Niño and following 2016–2017 La Niña. However, in 2015–2016 the eastern African impacts were displaced to the west and south of the canonical pattern. Composites of seasonal vegetation anomalies highlight the magnitude and position of impacts. Further investigation through empirical orthogonal teleconnections and spatial correlation analysis confirms the similar, but opposite, teleconnection impacts in eastern and southern Africa. The diametrically opposed patterns have particular implications for agricultural production and the availability of fodder and forage, especially in the pastoral communities of the two regions
A geopositioned and evidence-graded pan-species compendium of Mayaro virus occurrence
No full textMayaro Virus (MAYV) is an emerging health threat in the Americas that can cause febrile illness as well as debilitating arthralgia or arthritis. To better understand the geographic distribution of MAYV risk, we developed a georeferenced database of MAYV occurrence based on peer-reviewed literature and unpublished reports. Here we present this compendium, which includes both point and polygon locations linked to occurrence data documented from its discovery in 1954 until 2022. We describe all methods used to develop the database including data collection, georeferencing, management and quality-control. We also describe a customized grading system used to assess the quality of each study included in our review. The result is a comprehensive, evidence-graded database of confrmed MAYV occurrence in humans, non-human animals, and arthropods to-date, containing 262 geo-positioned occurrences in total. This database - which can be updated over time - may be useful for local spill-over risk assessment, epidemiological modelling to understand key transmission dynamics and drivers of MAYV spread, as well as identifcation of major surveillance gaps.Fil: Celone, Michael. Uniformed Services University of the Health Sciences; Estados UnidosFil: Potter, Alexander M.. Walter Reed Army Institute of Research,; Estados Unidos. Walter Reed Biosystematics Unit; Estados UnidosFil: Han, Barbara A.. Cary Institute of Ecosystem Studies; Estados UnidosFil: Beeman, Sean P.. Uniformed Services University of the Health Sciences; Estados UnidosFil: Okech, Bernard. Uniformed Services University of the Health Sciences; Estados UnidosFil: Forshey, Brett. Armed Forces Health Surveillance Center; Estados UnidosFil: Dunford, James. Uniformed Services University of the Health Sciences; Estados UnidosFil: Rutherford, George. University of California; Estados UnidosFil: Mita Mendoza, Neida K.. Wadsworth Center. State of New York Department of Health; Estados UnidosFil: Estallo, Elizabet Lilia. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Khouri, Ricardo. Instituto Gonçalo Moniz-Fiocruz; BrasilFil: de Siqueira, Isadora Cristina. Instituto Gonçalo Moniz-Fiocruz; BrasilFil: Petersen, Kyle. Uniformed Services University of the Health Sciences; Estados UnidosFil: Maves, Ryan C.. Wake Forest University School Of Medicine; Estados Unidos. Uniformed Services University of the Health Sciences; Estados UnidosFil: Anyamba, Assaf. Oak Ridge National Laboratory; Estados UnidosFil: Pollett, Simon. Henry M. Jackson Foundation for the Advancement of Military Medicine; Estados Unidos. Uniformed Services University of the Health Sciences; Estados Unido
Climate-disease connections: Rift Valley Fever in Kenya Relações entre clima e doença: febre do Vale do Rift, no Quênia
No full textAll known Rift Valley fever(RVF) outbreaks in Kenya from 1950 to 1998 followed periods of abnormally high rainfall. On an interannual scale, periods of above normal rainfall in East Africa are associated with the warm phase of the El Niño/Southern Oscillation (ENSO) phenomenon. Anomalous rainfall floods mosquito-breeding habitats called dambos, which contain transovarially infected mosquito eggs. The eggs hatch Aedes mosquitoes that transmit the RVF virus preferentially to livestock and to humans as well. Analysis of historical data on RVF outbreaks and indicators of ENSO (including Pacific and Indian Ocean sea surface temperatures and the Southern Oscillation Index) indicates that more than three quarters of the RVF outbreaks have occurred during warm ENSO event periods. Mapping of ecological conditions using satellite normalized difference vegetation index (NDVI) data show that areas where outbreaks have occurred during the satellite recording period (1981-1998) show anomalous positive departures in vegetation greenness, an indicator of above-normal precipitation. This is particularly observed in arid areas of East Africa, which are predominantly impacted by this disease. These results indicate a close association between interannual climate variability and RVF outbreaks in Kenya.Entre 1950 e 1998 houve surtos de febre no Vale do Rift, no Quênia, após períodos de aumentos pluviométricos anormais. Em escala interanual, esses períodos estiveram associados à fase quente do fenômeno ENSO (El Niño/Southern Oscillation) na África Oriental. As chuvas alagam os criadouros de mosquitos - dambos -, cujos ovos, infectados pela via transovariana, eclodem, produzindo mosquitos Aedes, transmissores do vírus da febre do Vale do Rift aos seres humanos e, em especial, ao gado. A análise dos dados históricos sobre surtos de febre do Vale do Rift e indicadores do fenômeno ENSO - incluindo temperaturas superficiais dos Oceanos Pacífico e Índico e o Índice de Oscilação Sul - mostrou que mais de 75% dos surtos ocorreram em períodos quentes do ENSO. Na época estudada - 1981-1998 -, o mapeamento das condições ecológicas via satélite (NDVI)- com dados normalizados sobre diferenças na vegetação - evidenciou que as áreas de surto apresentaram desvios anômalos na intensidade do verde da vegetação (indicador de pluviosidade alta), em particular, nas regiões áridas da África Oriental - as mais afetadas pela febre. Os resultados indicam associação estreita entre variabilidade climática interanual e surtos de febre do Vale do Rift no Quênia
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