D as human related risk factor whereas this way is I-BRD9 site suspected to be the main route of human infection in other studies [31]. In our sample, the number of people in contact with fresh blood was very low resulting in a low statistical power. However, this way of transmission has still to be considered, especially in the areas unfavorable to mosquitoes where direct contact could explain human infections [15]. Our integrated approach analyzing environmental, cattle and human datasets allow us to bring new insight on RVF transmission patterns in Madagascar. The association between cattle seroprevalence, humid environments and high cattle density suggests that concomitant vectorial and direct transmissions are critical to maintain RVFV enzootic transmission. Even if the 2008?9 outbreaks are suspected to be associated with infected domestic animals imported from east Africa [56], our study confirms that enzootic and endemic circulations occur in Madagascar as suggested before [3,12,21]. The identification of at-risk environments is essential to focus veterinary surveillance and control of RVFV. Because of the variety of ecosystems and socio-cultural practices in Madagascar, it is likely that some areas are more favorable to direct transmission [3,19], while others are more favorable to vectorial transmission or to both transmission pathways. In the at-risk humid environment of the western, north-western and the eastern-coast areas, suitable for Culex and Anopheles mosquitoes, vectorial transmission probably occur in both cattle and human. In the future, mathematical modeling may be used to decipher the relative contribution of each transmission pathway in both human and ruminants, integrate the role of animal trade in disease spread in the Malagasy context, and thus propose adapted surveillance and control measures.PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,13 /Rift CBR-5884 chemical information Valley Fever Risk Factors in MadagascarSupporting InformationS1 Table. Comparison of the values and weight of AIC for the cattle and human models. (DOCX) S1 Appendix. Scatterplot of observed versus predicted seroprevalences at the district level. Seroprevalence has been predicted for each age category in each communes sampled. For each district the sampling has been reconstructed taking into account the communes sampled and the number of animals sampled in each commune. Grey points correspond to districts where less than 5 animals were sampled. (DOCX)AcknowledgmentsWe especially thank the population of Madagascar who participated to the studies. We thank those who facilitated the survey, i.e., heads of fokontany, local administration authorities and health authorities from Ministry of Health. We also thank the Plague Unit at the Institut Pasteur de Madagascar for data collection and supporting (S. Telfer, C. Rahaingosoamamitiana, F. M. Andriamiarimanana, S. Rahelinirina, M. Rajerison), S. Andrimasinoro for the management of data, B.S. Rahoilijaona H.A. Rakotoarison, H. Raharimampianina and A.M. Rakotohaingomahefa for their field supports. We are grateful to the authors of the cattle survey and especially E. Jeanmaire, J.M. Reynes and S. de la Rocque for providing the data of cattle survey. We thank G. Gray from the Division of Infectious Diseases of Duke University for its support. Finally, we thank three anonymous reviewers for their careful reading of our manuscript and their comments and suggestions.Author ContributionsConceived and designed the experimen.D as human related risk factor whereas this way is suspected to be the main route of human infection in other studies [31]. In our sample, the number of people in contact with fresh blood was very low resulting in a low statistical power. However, this way of transmission has still to be considered, especially in the areas unfavorable to mosquitoes where direct contact could explain human infections [15]. Our integrated approach analyzing environmental, cattle and human datasets allow us to bring new insight on RVF transmission patterns in Madagascar. The association between cattle seroprevalence, humid environments and high cattle density suggests that concomitant vectorial and direct transmissions are critical to maintain RVFV enzootic transmission. Even if the 2008?9 outbreaks are suspected to be associated with infected domestic animals imported from east Africa [56], our study confirms that enzootic and endemic circulations occur in Madagascar as suggested before [3,12,21]. The identification of at-risk environments is essential to focus veterinary surveillance and control of RVFV. Because of the variety of ecosystems and socio-cultural practices in Madagascar, it is likely that some areas are more favorable to direct transmission [3,19], while others are more favorable to vectorial transmission or to both transmission pathways. In the at-risk humid environment of the western, north-western and the eastern-coast areas, suitable for Culex and Anopheles mosquitoes, vectorial transmission probably occur in both cattle and human. In the future, mathematical modeling may be used to decipher the relative contribution of each transmission pathway in both human and ruminants, integrate the role of animal trade in disease spread in the Malagasy context, and thus propose adapted surveillance and control measures.PLOS Neglected Tropical Diseases | DOI:10.1371/journal.pntd.July 14,13 /Rift Valley Fever Risk Factors in MadagascarSupporting InformationS1 Table. Comparison of the values and weight of AIC for the cattle and human models. (DOCX) S1 Appendix. Scatterplot of observed versus predicted seroprevalences at the district level. Seroprevalence has been predicted for each age category in each communes sampled. For each district the sampling has been reconstructed taking into account the communes sampled and the number of animals sampled in each commune. Grey points correspond to districts where less than 5 animals were sampled. (DOCX)AcknowledgmentsWe especially thank the population of Madagascar who participated to the studies. We thank those who facilitated the survey, i.e., heads of fokontany, local administration authorities and health authorities from Ministry of Health. We also thank the Plague Unit at the Institut Pasteur de Madagascar for data collection and supporting (S. Telfer, C. Rahaingosoamamitiana, F. M. Andriamiarimanana, S. Rahelinirina, M. Rajerison), S. Andrimasinoro for the management of data, B.S. Rahoilijaona H.A. Rakotoarison, H. Raharimampianina and A.M. Rakotohaingomahefa for their field supports. We are grateful to the authors of the cattle survey and especially E. Jeanmaire, J.M. Reynes and S. de la Rocque for providing the data of cattle survey. We thank G. Gray from the Division of Infectious Diseases of Duke University for its support. Finally, we thank three anonymous reviewers for their careful reading of our manuscript and their comments and suggestions.Author ContributionsConceived and designed the experimen.
