Climate-based risk models for Fasciola hepatica in Colombia

Valencia-López, Natalia and Malone, John B. and Gómez Carmona, Catalina and Velásquez, Luz E. (2012) Climate-based risk models for Fasciola hepatica in Colombia. Geospatial health, 6 (3). S75-S85. ISSN 1970-7096

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A predictive Fasciola hepatica model, based on the growing degree day-water budget (GDD-WB) concept and the known biological requirements of the parasite, was developed within a geographical information system (GIS) in Colombia. Climate-based forecast index (CFI) values were calculated and represented in a national-scale, climate grid (18 x 18 km) using ArcGIS 9.3. A mask overlay was used to exclude unsuitable areas where mean annual temperature exceeded 25 °C, the upper threshold for development and propagation of the F. hepatica life cycle. The model was then validated and further developed by studies limited to one department in northwest Colombia. F. hepatica prevalence data was obtained from a 2008-2010 survey in 10 municipalities of 6,016 dairy cattle at 673 herd study sites, for which global positioning system coordinates were recorded. The CFI map results were compared to F. hepatica environmental risk models for the survey data points that had over 5% prevalence (231 of the 673 sites) at the 1 km2 scale using two independent approaches: (i) a GIS map query based on satellite data parameters including elevation, enhanced vegetation index and land surface temperature day-night difference; and (ii) an ecological niche model (MaxEnt), for which geographic point coordinates of F. hepatica survey farms were used with BioClim data as environmental variables to develop a probability map. The predicted risk pattern of both approaches was similar to that seen in the forecast index grid. The temporal risk, evaluated by the monthly CFIs and a daily GDD-WB forecast software for 2007 and 2008, revealed a major July-August to January transmission period with considerable inter-annual differences.

Item Type: Article
Uncontrolled Keywords: Fasciola hepatica, Colombia, climate forecast, geographical information systems, maximum entropy, ecologic niche modelling.
Subjects: 600 Tecnologia - Scienze applicate > 610 Medicina e salute (Classificare qui la tecnologia dei servizi medici) > 616 Malattie (classificare qui la Clinica medica, la medicina basata sull'evidenza, la Medicina interna, la Medicina sperimentale) > 616.9 Altre malattie (altri rami della Medicina) > 616.96 Parassitosi, malattie causate da funghi (micosi) (classificare qui la Parassitologia medica) > 616.963 Malattie causate da trematodi (infezioni da trematodi) (include la schistosomiasi)
Depositing User: Luca Tiberi
Date Deposited: 12 Sep 2019 09:49
Last Modified: 12 Sep 2019 09:49

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