He site of sampling as random effect. Firstly, the cattle seroprevalence dataset was split randomly into 10 parts. Then, the model was fitted to 90 of the data and used to predict the serological status of the remaining 10 individuals as validation step. The procedure was performed 10 times, each time with 1 of the 10 parts as validation step. [42]. Finally, parameter estimations derived from the best cattle model were used to predict and map cattle seroprevalence at the commune scale for the whole island. Data analyses were performed using R software version 3.0.1 [43?9].Results Environmental characterization of Malagasy communesFour MFA factors contributing to 60 of the total variance were selected. Table 1 shows the ARRY-334543 biological activity Mequitazine biological activity correlation between each quantitative covariate included in the MFA and each of these four factors: ?Factor 1 separated areas based on seasonality in primary productivity (photosynthetic activity measured by NDVI), vegetation, land use and temperature. Large positive values described ecosystems with high seasonal primary productivity dominated by herbaceous vegetation and with low surfaces of crops under dry and hot climatic conditions (Fig 2A inPLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,6 /Rift Valley Fever Risk Factors in MadagascarTable 1. Correlation between each quantitative covariate included in the MFA and each factor (Factor 1, Factor 2, Factor 3 and Factor 4). Covariate Mean LST-day Mean LST-night Mean precipitation Seasonality of precipitation Mean NDVI NDVI seasonality Herbaceous Shrubs Wood rees Urbanization Crops Irrigated area Wetlands Water bodies Marshlands Factor 1 0.92 0.50 -0.70 0.17 -0.83 0.63 0.84 0.11 -0.33 / -0.62 / / / / Factor 2 -0.19 -0.66 / -0.15 -0.34 0.45 -0.12 0.40 0.56 0.14 -0.61 0.66 0.24 / 0.07 Factor 3 0.11 0.14 0.32 0.82 / 0.08 -0.24 0.30 0.37 -0.30 -0.24 -0.08 -0.39 0.07 0.18 Factor 4 / 0.26 0.31 0.09 / 0.08 0.11 -0.17 -0.19 0.27 0.10 0.37 0.46 0.22 0./: The correlation coefficients were not significantly different from zero and so not included in the results doi:10.1371/journal.pntd.0004827.tgreen). Large negative values described ecosystems with low seasonal primary productivity including crops under wet and less hot climatic conditions (Fig 2A in brown). The communes with the largest positive values for Factor1 are located in the south-western part of Madagascar (Fig 2A in green) while the communes with the largest negative values for Factor1 are located on the north-eastern part (Fig 2A in brown); ?Factor 2 separated areas based on seasonality in primary productivity, vegetation, land use and temperature. Large positive values described ecosystems with high seasonal primaryFig 2. Geographical representation of the MFA factor values and cattle density of the 1,578 Malagasy communes. (A) Factor 1, (B) Factor 2, (C) Factor 3, (D) Factor 4, (E) cattle density categories. For each factor, green colors represent positive values and brown negative values. The darkest colors represent the highest values. Cattle were sampled in communes surrounded in black and human were enrolled in communes surrounded in purple. doi:10.1371/journal.pntd.0004827.gPLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,7 /Rift Valley Fever Risk Factors in Madagascarproductivity including ligneous vegetation and irrigated areas (rice fields) under climatic conditions characterized by low night temperatures (Fig 2B in green). Large negative values described ecosystems wit.He site of sampling as random effect. Firstly, the cattle seroprevalence dataset was split randomly into 10 parts. Then, the model was fitted to 90 of the data and used to predict the serological status of the remaining 10 individuals as validation step. The procedure was performed 10 times, each time with 1 of the 10 parts as validation step. [42]. Finally, parameter estimations derived from the best cattle model were used to predict and map cattle seroprevalence at the commune scale for the whole island. Data analyses were performed using R software version 3.0.1 [43?9].Results Environmental characterization of Malagasy communesFour MFA factors contributing to 60 of the total variance were selected. Table 1 shows the correlation between each quantitative covariate included in the MFA and each of these four factors: ?Factor 1 separated areas based on seasonality in primary productivity (photosynthetic activity measured by NDVI), vegetation, land use and temperature. Large positive values described ecosystems with high seasonal primary productivity dominated by herbaceous vegetation and with low surfaces of crops under dry and hot climatic conditions (Fig 2A inPLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,6 /Rift Valley Fever Risk Factors in MadagascarTable 1. Correlation between each quantitative covariate included in the MFA and each factor (Factor 1, Factor 2, Factor 3 and Factor 4). Covariate Mean LST-day Mean LST-night Mean precipitation Seasonality of precipitation Mean NDVI NDVI seasonality Herbaceous Shrubs Wood rees Urbanization Crops Irrigated area Wetlands Water bodies Marshlands Factor 1 0.92 0.50 -0.70 0.17 -0.83 0.63 0.84 0.11 -0.33 / -0.62 / / / / Factor 2 -0.19 -0.66 / -0.15 -0.34 0.45 -0.12 0.40 0.56 0.14 -0.61 0.66 0.24 / 0.07 Factor 3 0.11 0.14 0.32 0.82 / 0.08 -0.24 0.30 0.37 -0.30 -0.24 -0.08 -0.39 0.07 0.18 Factor 4 / 0.26 0.31 0.09 / 0.08 0.11 -0.17 -0.19 0.27 0.10 0.37 0.46 0.22 0./: The correlation coefficients were not significantly different from zero and so not included in the results doi:10.1371/journal.pntd.0004827.tgreen). Large negative values described ecosystems with low seasonal primary productivity including crops under wet and less hot climatic conditions (Fig 2A in brown). The communes with the largest positive values for Factor1 are located in the south-western part of Madagascar (Fig 2A in green) while the communes with the largest negative values for Factor1 are located on the north-eastern part (Fig 2A in brown); ?Factor 2 separated areas based on seasonality in primary productivity, vegetation, land use and temperature. Large positive values described ecosystems with high seasonal primaryFig 2. Geographical representation of the MFA factor values and cattle density of the 1,578 Malagasy communes. (A) Factor 1, (B) Factor 2, (C) Factor 3, (D) Factor 4, (E) cattle density categories. For each factor, green colors represent positive values and brown negative values. The darkest colors represent the highest values. Cattle were sampled in communes surrounded in black and human were enrolled in communes surrounded in purple. doi:10.1371/journal.pntd.0004827.gPLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,7 /Rift Valley Fever Risk Factors in Madagascarproductivity including ligneous vegetation and irrigated areas (rice fields) under climatic conditions characterized by low night temperatures (Fig 2B in green). Large negative values described ecosystems wit.