Oss-sectional serological survey performed in August 2008 on 3,450 ruminants [17]. Only cattle with known breeding location were included in the study (n = 1,432; Fig 1; [17]). The human dataset contained data from a national cross-sectional serological survey conducted from November 2011 to April 2012 and from October 2012 to May 2013 in 56 sites (cities or I-BRD9 site villages). Six percent of these sera were used in a previous study [21]. In each of these sites, 30 adults were randomly chosen and sampled on a voluntary basis (Fig 1). Potential contacts with ruminants or fresh ruminant fluids (secretion, blood, milk) and socio-professional categories–butcher, farmer, health worker, worker in contact with environment (water, forest) and others (teacher, student, administrative worker, retired)–were documented through a dedicated questionnaire.Ethics statementThe cattle study was performed in collaboration with the Malagasy Veterinary Services and animals were sampled by qualified veterinarians [17]. The human study protocol was approved by the Malagasy competent authorities, the Malagasy Ethic National Committee (authorization N?66/MSAMP/CE, 26th July 2011). After reading of the informed consent letter, written and oral consent was obtained from volunteering individuals. Participants were sampled by qualified investigators and the data were analyzed anonymously.PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,3 /Rift Valley Fever Risk Factors in MadagascarFig 1. Cattle and human sampling sites [17]. Animal and human sera were analyzed using commercial ELISA kits (Biological Diagnostic Supplies Ltd., BDSL) to detect anti-RVFV immunoglobulin (Ig) G [17,22,23]. Cattle and human data were aggregated at the commune level (n = 1,578). doi:10.1371/journal.pntd.0004827.gCovariatesThe following covariates were selected according to their putative influence on mosquito density and population dynamics or on the risk of contact with ruminants: ?Cattle density. This variable has previously been identified as a risk factor for RVF transmission [7,24]. ?Surface covered by water bodies and landscape classes (such as forest, shrub, and agricultural areas). Density and population dynamics of vectors are influenced by AMG9810 web environmental factors such as climate, the presence of water bodies and other landscape features [1,25]. The presence of temporary water bodies and floodplains are known as risk factors for RVF in semiarid areas in eastern Africa, the Arabian Peninsula and Western Africa [1]. Artificial water bodies such as dam and irrigated rice fields are also known to be associated with high abundance of RVFV vectors in western Africa [1]. Furthermore, RVFV transmission occurred in forested or shrubby areas [5,8,26,27]. A recent study details the mosquito species and their habitat in Madagascar [28]. Briefly, RVF potential mosquito vectors belong to the genera Aedes, Anopheles, Culex, Eretmapodites and Mansonia [28]. The breeding areas of the Aedes genus are mostly associated with temporary water bodies such as flooded area, temporary pond, puddles, rice field [28]. Culex and Anopheles mosquitoes breeding areas are diversified and could be temporary (rice field, swamps) or permanent (lakes, pond). Stagnant and permanent water bodies are the habitat of Eretmapodites and Mansonia respectively [28]. ?Rainfall, Normalized Difference Vegetation Index (NDVI) and temperatures. The risk of RVFV infection in Eastern and Southern Africa has been shown to.Oss-sectional serological survey performed in August 2008 on 3,450 ruminants [17]. Only cattle with known breeding location were included in the study (n = 1,432; Fig 1; [17]). The human dataset contained data from a national cross-sectional serological survey conducted from November 2011 to April 2012 and from October 2012 to May 2013 in 56 sites (cities or villages). Six percent of these sera were used in a previous study [21]. In each of these sites, 30 adults were randomly chosen and sampled on a voluntary basis (Fig 1). Potential contacts with ruminants or fresh ruminant fluids (secretion, blood, milk) and socio-professional categories–butcher, farmer, health worker, worker in contact with environment (water, forest) and others (teacher, student, administrative worker, retired)–were documented through a dedicated questionnaire.Ethics statementThe cattle study was performed in collaboration with the Malagasy Veterinary Services and animals were sampled by qualified veterinarians [17]. The human study protocol was approved by the Malagasy competent authorities, the Malagasy Ethic National Committee (authorization N?66/MSAMP/CE, 26th July 2011). After reading of the informed consent letter, written and oral consent was obtained from volunteering individuals. Participants were sampled by qualified investigators and the data were analyzed anonymously.PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,3 /Rift Valley Fever Risk Factors in MadagascarFig 1. Cattle and human sampling sites [17]. Animal and human sera were analyzed using commercial ELISA kits (Biological Diagnostic Supplies Ltd., BDSL) to detect anti-RVFV immunoglobulin (Ig) G [17,22,23]. Cattle and human data were aggregated at the commune level (n = 1,578). doi:10.1371/journal.pntd.0004827.gCovariatesThe following covariates were selected according to their putative influence on mosquito density and population dynamics or on the risk of contact with ruminants: ?Cattle density. This variable has previously been identified as a risk factor for RVF transmission [7,24]. ?Surface covered by water bodies and landscape classes (such as forest, shrub, and agricultural areas). Density and population dynamics of vectors are influenced by environmental factors such as climate, the presence of water bodies and other landscape features [1,25]. The presence of temporary water bodies and floodplains are known as risk factors for RVF in semiarid areas in eastern Africa, the Arabian Peninsula and Western Africa [1]. Artificial water bodies such as dam and irrigated rice fields are also known to be associated with high abundance of RVFV vectors in western Africa [1]. Furthermore, RVFV transmission occurred in forested or shrubby areas [5,8,26,27]. A recent study details the mosquito species and their habitat in Madagascar [28]. Briefly, RVF potential mosquito vectors belong to the genera Aedes, Anopheles, Culex, Eretmapodites and Mansonia [28]. The breeding areas of the Aedes genus are mostly associated with temporary water bodies such as flooded area, temporary pond, puddles, rice field [28]. Culex and Anopheles mosquitoes breeding areas are diversified and could be temporary (rice field, swamps) or permanent (lakes, pond). Stagnant and permanent water bodies are the habitat of Eretmapodites and Mansonia respectively [28]. ?Rainfall, Normalized Difference Vegetation Index (NDVI) and temperatures. The risk of RVFV infection in Eastern and Southern Africa has been shown to.