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1. Larval nutritional stress affects vector life history traits and human malaria transmission

Author

Thierry Lefèvre, Amélie Vantaux, Anna Cohuet, Olivier Roux, Benjamin Roche, Kounbobr Roch Dabiré, Maladies infectieuses et vecteurs : écologie, génétique, évolution et contrôle (MIVEGEC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut de Recherche en Sciences de la Santé (IRSS), CNRST, Transmission-Interactions-Adaptations hôtes/vecteurs/pathogènes (MIVEGEC-TRIAD), Evolution des Systèmes Vectoriels (ESV), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Maladies infectieuses et vecteurs : écologie, génétique, évolution et contrôle (MIVEGEC), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut de Recherche en Sciences de la Santé (IRSS) / Centre Muraz, Unité de modélisation mathématique et informatique des systèmes complexes [Bondy] (UMMISCO), Université Cadi Ayyad [Marrakech] (UCA)-Université de Yaoundé I-Université Gaston Bergé (Saint-Louis, Sénégal)-Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD)-Institut de la francophonie pour l'informatique-Université Pierre et Marie Curie - Paris 6 (UPMC), Diversity, ecology, evolution & Adaptation of arthropod vectors (MIVEGEC-DEEVA), This study was funded by the ANR grant 11-PDOC-006-01 to TL., We would like to thank all of the children and their parents who participated in this study, as well as the local authorities for their support, and Andrea Yockey-Dejean for proofreading the paper. We are very grateful to the IRSS staff in Burkina Faso for technical assistance., and Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Yaoundé I-Institut de la francophonie pour l'informatique-Université Cheikh Anta Diop [Dakar, Sénégal] (UCAD)-Université Gaston Bergé (Saint-Louis, Sénégal)-Université Cadi Ayyad [Marrakech] (UCA)

Subjects
0301 basic medicine, media_common.quotation_subject, [SDV]Life Sciences [q-bio], Plasmodium falciparum, Zoology, Insect, MESH: Insect Vectors, Biology, Article, law.invention, Life history theory, 03 medical and health sciences, MESH: Plasmodium falciparum/growth & development, law, Stress, Physiological, Anopheles, parasitic diseases, medicine, Gametocyte, Animals, Humans, MESH: Animals, MESH: Stress, Physiological, Life History Traits, media_common, Larva, Multidisciplinary, MESH: Humans, MESH: Life History Traits, MESH: Anopheles/parasitology, Ecology, fungi, MESH: Anopheles/growth & development, medicine.disease, Fecundity, 3. Good health, Insect Vectors, Malaria, MESH: Larva/parasitology, MESH: Malaria/transmission, 030104 developmental biology, Transmission (mechanics), MESH: Larva/growth & development, Vector (epidemiology), Female, MESH: Female
Abstract

Exposure to stress during an insect’s larval development can have carry-over effects on adult life history traits and susceptibility to pathogens. We investigated the effects of larval nutritional stress for the first time using field mosquito vectors and malaria parasites. In contrast to previous studies, we show that larval nutritional stress may affect human to mosquito transmission antagonistically: nutritionally deprived larvae showed lower parasite prevalence for only one gametocyte carrier; they also had lower fecundity. However, they had greater survival rates that were even higher when infected. When combining these opposing effects into epidemiological models, we show that larval nutritional stress induced a decrease in malaria transmission at low mosquito densities and an increase in transmission at high mosquito densities, whereas transmission by mosquitoes from well-fed larvae was stable. Our work underscores the importance of including environmental stressors towards understanding host–parasite dynamics to improve disease transmission models and control.

Published
2016

2. Integrated Analysis of Environment, Cattle and Human Serological Data: Risks and Mechanisms of Transmission of Rift Valley Fever in Madagascar

Author

Annelise Tran, Vladimir Grosbois, Jean-Pierre Ravalohery, Fanjasoa Rakotomanana, Jean-Michel Heraud, Soa Fy Andriamandimby, Christophe Rogier, Seta Andriamamonjy, Véronique Chevalier, Benoit Durand, Marie-Marie Olive, Animal et gestion intégrée des risques (UPR AGIRs), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad), Unité de Virologie [Antananarivo, Madagascar] (IPM), Institut Pasteur de Madagascar, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP), Laboratoire de santé animale, sites de Maisons-Alfort et de Dozulé, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Réseau International des Instituts Pasteur (RIIP), This study was supported in part by funds raised by (i) CIRAD (ii) the Centre National d'Etudes Spatiales (CNES, grant # 131163/00) (iii) the Institut Pasteur de Madagascar. Human field work was funded by the Institut Pasteur of Madagascar (Internal Project through the ZORA (ZOonoses, Rodent and Arboviruses) project and the Centers for Disease Control and Prevention (CDC, and Cooperative Agreement #U51/IP000327). Moreover, this material is based upon work supported by the U. S. Department of Homeland Security under the Center of Excellence of Emerging and Zoonotic Animal Diseases Grant Award Number 2010-ST061-AG0001. Cattle study was supported in part by funds raised by World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) through the Central Emergency Response Fund of the United Nations. The views and conclusions contained in this paper are those of the authors and should not be interpreted as necessarily representing the official policies, either explicit or implicit, of the U. S. Department of Homeland Security. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Subjects
Veterinary medicine, Epidemiology, Pathology and Laboratory Medicine, law.invention, 0302 clinical medicine, [SDV.MHEP.MI]Life Sciences [q-bio]/Human health and pathology/Infectious diseases, Analyse du risque, MESH: Cattle Diseases, MESH: Animals, Neglected tropical diseases, Mammals, [SDV.MHEP.ME]Life Sciences [q-bio]/Human health and pathology/Emerging diseases, MESH: Middle Aged, 000 - Autres thèmes, Fièvre de la Vallée du Rift, Anopheles, Ruminants, 3. Good health, Transmission (mechanics), MESH: Young Adult, Densité de population, [SDV.MP.VIR]Life Sciences [q-bio]/Microbiology and Parasitology/Virology, Enzootic, Infectious diseases, L72 - Organismes nuisibles des animaux, Genre humain, Bétail, Livestock, lcsh:RC955-962, MESH: Culex, Microbiology, MESH: Anopheles, 03 medical and health sciences, MESH: Cross-Sectional Studies, Madagascar, MESH: Humans, MESH: Seroepidemiologic Studies, Tropical diseases, Public Health, Environmental and Occupational Health, Organisms, lcsh:RA1-1270, MESH: Adult, [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology, 15. Life on land, medicine.disease, Invertebrates, Insect Vectors, 030104 developmental biology, Africa, Cattle, MESH: Female, MESH: Antibodies, Viral, 0301 basic medicine, RNA viruses, Cattle Diseases, Disease Vectors, L73 - Maladies des animaux, Mosquitoes, Serology, Geographical Locations, MESH: Madagascar, law, Zoonoses, Facteur de risque, Bunyaviruses, Medicine and Health Sciences, MESH: Rift Valley Fever, Comportement humain, Rift Valley fever, 2. Zero hunger, biology, lcsh:Public aspects of medicine, Agriculture, Facteur du milieu, Medical microbiology, Insects, MESH: Cattle, Vecteur de maladie, Vertebrates, Viruses, MESH: Rift Valley fever virus, Seasons, Pathogens, Research Article, lcsh:Arctic medicine. Tropical medicine, Zone humide, Arthropoda, Distribution géographique, Culex, 030231 tropical medicine, Viral diseases, MESH: Insect Vectors, Virus de la fièvre de la vallée du Rift, Sérologie, Bovines, medicine, Seroprevalence, Animals, MESH: Environment, Transmission des maladies, Biology and life sciences, Viral pathogens, Morbidité, biology.organism_classification, Rift Valley fever virus, MESH: Male, Microbial pathogens, Amniotes, People and Places, Earth Sciences, [SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie
Abstract

Background Rift Valley fever (RVF) is a vector-borne disease affecting ruminants and humans. Madagascar was heavily affected by RVF in 2008–2009, with evidence of a large and heterogeneous spread of the disease. The identification of at-risk environments is essential to optimize the available resources by targeting RVF surveillance in Madagascar. Herein, the objectives of our study were: (i) to identify the environmental factors and areas favorable to RVF transmission to both cattle and human and (ii) to identify human behaviors favoring human infections in Malagasy contexts. Methodology/Principal Findings First, we characterized the environments of Malagasy communes using a Multiple Factor Analysis (MFA). Then, we analyzed cattle and human serological data collected at national level using Generalized Linear Mixed Models, with the individual serological status (cattle or human) as the response, and MFA factors, as well as other potential risk factors (cattle density, human behavior) as explanatory variables. Cattle and human seroprevalence rates were positively associated to humid environments (p, Author Summary Rift Valley fever virus (RVFV) is a pathogen that causes a vector-borne tropical disease. The disease affects ruminants and humans and severely impacts the health and economy of affected countries. Madagascar was heavily affected by Rift Valley fever (RVF) in 2008–2009, with evidence of a large and heterogeneous spread of the disease. Our study aims at identifying environmental and human-related risk factors for RVFV transmission. First, we characterized Malagasy environments according to their putative influence on RVFV mosquito density and population dynamics. Then we statistically analyzed cattle and human serological data collected at a national level with the individual serological status as response, and Malagasy environments previously characterized by climatic and landscape variables as well as other potential risk factors as explanatory variables. Our results identified humid environments of the western, north-western and eastern parts of the island as risky areas. The identification of at-risk environments is essential to focus veterinary surveillance and control of RVFV.

Published
2016