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Acosta D, Barrow A, Mahamadou IS, Assuncao VS, Edwards ME, McKune SL. Climate change and health in the Sahel: a systematic review. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231602. [PMID: 39021778 PMCID: PMC11251769 DOI: 10.1098/rsos.231602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 05/07/2024] [Accepted: 06/11/2024] [Indexed: 07/20/2024]
Abstract
The Sahel region is projected to be highly impacted by the more frequent hazards associated with climate change, including increased temperature, drought and flooding. This systematic review examined the evidence for climate change-related health consequences in the Sahel. The databases used were Medline (PubMed), Embase (Ovid), Web of Science (Clarivate) and CABI Global Health. Hand searches were also conducted, which included directly engaging Sahelian researchers and hand-searching in the African Journals Online database. Of the 4153 studies found, 893 were identified as duplicates and the remaining 3260 studies were screened (title and abstract only) and then assessed for eligibility. A total of 81 studies were included in the systematic review. Most studies focused on vector-borne diseases, food security, nutrition and heat-related stress. Findings suggest that mosquito distribution will shift under different climate scenarios, but this relationship will not be linear with temperature, as there are other variables to consider. Food insecurity, stunting (chronic malnutrition) and heat-related mortality are likely to increase if no action is taken owing to the projected impact of climate change on environmental factors and agriculture. Seventy-one per cent of manuscripts (n = 58) had first authors from institutions in North America or Europe, of which 39.7% (n = 23) included co-authors from African institutions.
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Affiliation(s)
- Daniel Acosta
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA
- Sahel Research Group, University of Florida, Gainesville, FL, USA
- Center for African Studies, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, USA
| | - Amadou Barrow
- Department of Epidemiology, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA
| | - Idrissa Saidou Mahamadou
- Department of Sociology and Rural Economy, Faculty of Agronomy, Abdou Moumouni University of Niamey, Niamey, Niger
| | - Victoria Simoni Assuncao
- Department of Geography, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, USA
| | - Mary E. Edwards
- Health Science Center Libraries, University of Florida, Gainesville, FL, USA
| | - Sarah L. McKune
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL, USA
- Sahel Research Group, University of Florida, Gainesville, FL, USA
- Center for African Studies, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, USA
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Doumbia M, Coulibaly JT, Silué DK, Cissé G, N’Dione JA, Koné B. Effects of Climate Variability on Malaria Transmission in Southern Côte d'Ivoire, West Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:7102. [PMID: 38063532 PMCID: PMC10706663 DOI: 10.3390/ijerph20237102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 09/04/2023] [Accepted: 09/15/2023] [Indexed: 12/18/2023]
Abstract
Malaria continues to be a major public health concern with a substantial burden in Africa. Even though it has been widely demonstrated that malaria transmission is climate-driven, there have been very few studies assessing the relationship between climate variables and malaria transmission in Côte d'Ivoire. We used the VECTRI model to predict malaria transmission in southern Côte d'Ivoire. First, we tested the suitability of VECTRI in modeling malaria transmission using ERA5 temperature data and ARC2 rainfall data. We then used the projected climatic data pertaining to 2030, 2050, and 2080 from a set of 14 simulations from the CORDEX-Africa database to compute VECTRI outputs. The entomological inoculation rate (EIR) from the VECTRI model was well correlated with the observed malaria cases from 2010 to 2019, including the peaks of malaria cases and the EIR. However, the correlation between the two parameters was not statistically significant. The VECTRI model predicted an increase in malaria transmissions in both scenarios (RCP8.5 and RCP4.5) for the time period 2030 to 2080. The monthly EIR for RCP8.5 was very high (1.74 to 1131.71 bites/person) compared to RCP4.5 (0.48 to 908 bites/person). These findings call for greater efforts to control malaria that take into account the impact of climatic factors.
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Affiliation(s)
- Madina Doumbia
- Unité de Formation et de Recherche des Sciences Biologiques, Université Péléforo Gon Coulibaly, Korhogo BP 1328, Côte d’Ivoire;
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS), Abidjan 01 BP 1303, Côte d’Ivoire; (J.T.C.); (D.K.S.)
| | - Jean Tenena Coulibaly
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS), Abidjan 01 BP 1303, Côte d’Ivoire; (J.T.C.); (D.K.S.)
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan 22 BP 582, Côte d’Ivoire
| | - Dieudonné Kigbafori Silué
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS), Abidjan 01 BP 1303, Côte d’Ivoire; (J.T.C.); (D.K.S.)
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan 22 BP 582, Côte d’Ivoire
| | - Guéladio Cissé
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, CH 4002 Basel, Switzerland;
- Faculty of Science, University of Basel, CH-4003 Basel, Switzerland
| | | | - Brama Koné
- Unité de Formation et de Recherche des Sciences Biologiques, Université Péléforo Gon Coulibaly, Korhogo BP 1328, Côte d’Ivoire;
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS), Abidjan 01 BP 1303, Côte d’Ivoire; (J.T.C.); (D.K.S.)
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Fall P, Diouf I, Deme A, Diouf S, Sene D, Sultan B, Famien AM, Janicot S. Bias-Corrected CMIP5 Projections for Climate Change and Assessments of Impact on Malaria in Senegal under the VECTRI Model. Trop Med Infect Dis 2023; 8:310. [PMID: 37368728 DOI: 10.3390/tropicalmed8060310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 05/19/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
On the climate-health issue, studies have already attempted to understand the influence of climate change on the transmission of malaria. Extreme weather events such as floods, droughts, or heat waves can alter the course and distribution of malaria. This study aims to understand the impact of future climate change on malaria transmission using, for the first time in Senegal, the ICTP's community-based vector-borne disease model, TRIeste (VECTRI). This biological model is a dynamic mathematical model for the study of malaria transmission that considers the impact of climate and population variability. A new approach for VECTRI input parameters was also used. A bias correction technique, the cumulative distribution function transform (CDF-t) method, was applied to climate simulations to remove systematic biases in the Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models (GCMs) that could alter impact predictions. Beforehand, we use reference data for validation such as CPC global unified gauge-based analysis of daily precipitation (CPC for Climate Prediction Center), ERA5-land reanalysis, Climate Hazards InfraRed Precipitation with Station data (CHIRPS), and African Rainfall Climatology 2.0 (ARC2). The results were analyzed for two CMIP5 scenarios for the different time periods: assessment: 1983-2005; near future: 2006-2028; medium term: 2030-2052; and far future: 2077-2099). The validation results show that the models reproduce the annual cycle well. Except for the IPSL-CM5B model, which gives a peak in August, all the other models (ACCESS1-3, CanESM2, CSIRO, CMCC-CM, CMCC-CMS, CNRM-CM5, GFDL-CM3, GFDL-ESM2G, GFDL-ESM2M, inmcm4, and IPSL-CM5B) agree with the validation data on a maximum peak in September with a period of strong transmission in August-October. With spatial variation, the CMIP5 model simulations show more of a difference in the number of malaria cases between the south and the north. Malaria transmission is much higher in the south than in the north. However, the results predicted by the models on the occurrence of malaria by 2100 show differences between the RCP8.5 scenario, considered a high emission scenario, and the RCP4.5 scenario, considered an intermediate mitigation scenario. The CanESM2, CMCC-CM, CMCC-CMS, inmcm4, and IPSL-CM5B models predict decreases with the RCP4.5 scenario. However, ACCESS1-3, CSIRO, NRCM-CM5, GFDL-CM3, GFDL-ESM2G, and GFDL-ESM2M predict increases in malaria under all scenarios (RCP4.5 and RCP8.5). The projected decrease in malaria in the future with these models is much more visible in the RCP8.5 scenario. The results of this study are of paramount importance in the climate-health field. These results will assist in decision-making and will allow for the establishment of preventive surveillance systems for local climate-sensitive diseases, including malaria, in the targeted regions of Senegal.
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Affiliation(s)
- Papa Fall
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Ibrahima Diouf
- Laboratoire de Physique de l'Atmosphère et de l'Océan-Siméon Fongang, Ecole Supérieure Polytechnique de l'Université Cheikh Anta Diop (UCAD), BP 5085, Dakar-Fann, Dakar 10700, Senegal
| | - Abdoulaye Deme
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Semou Diouf
- Laboratoire Environnement-Ingénierie-Télécommunication-Energies Renouvelables (LEITER), Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger de Saint-Louis, BP 234, Saint-Louis 32000, Senegal
| | - Doudou Sene
- Programme National de Lutte Contre le Paludisme (PNLP), BP 5085, Dakar-Fann, Dakar 10700, Senegal
| | - Benjamin Sultan
- ESPACE-DEV, Université Montpellier, IRD, Université Guyane, Université Réunion, Université Antilles, Université Avignon, 34093 Montpellier, France
| | - Adjoua Moïse Famien
- Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université, IRD, CNRS, MNHN, 75005 Paris, France
- Département de Sciences et Techniques, Université Alassane Ouattara de Bouaké, Bouaké 01 BPV 18, Côte d'Ivoire
| | - Serge Janicot
- Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques (LOCEAN), Sorbonne Université, IRD, CNRS, MNHN, 75005 Paris, France
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Mbouna AD, Tamoffo AT, Asare EO, Lenouo A, Tchawoua C. Malaria metrics distribution under global warming: assessment of the VECTRI malaria model over Cameroon. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2023; 67:93-105. [PMID: 36258135 DOI: 10.1007/s00484-022-02388-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 06/30/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Malaria is a critical health issue across the world and especially in Africa. Studies based on dynamical models helped to understand inter-linkages between this illness and climate. In this study, we evaluated the ability of the VECTRI community vector malaria model to simulate the spread of malaria in Cameroon using rainfall and temperature data from FEWS-ARC2 and ERA-interim, respectively. In addition, we simulated the model using five results of the dynamical downscaling of the regional climate model RCA4 within two time frames named near future (2035-2065) and far future (2071-2100), aiming to explore the potential effects of global warming on the malaria propagation over Cameroon. The evaluated metrics include the risk maps of the entomological inoculation rate (EIR) and the parasite ratio (PR). During the historical period (1985-2005), the model satisfactorily reproduces the observed PR and EIR. Results of projections reveal that under global warming, heterogeneous changes feature the study area, with localized increases or decreases in PR and EIR. As the level of radiative forcing increases (from 2.6 to 8.5 W.m-2), the magnitude of change in PR and EIR also gradually intensifies. The occurrence of transmission peaks is projected in the temperature range of 26-28 °C. Moreover, PR and EIR vary depending on the three agro-climatic regions of the study area. VECTRI still needs to integrate other aspects of disease transmission, such as population mobility and intervention strategies, in order to be more relevant to support actions of decision-makers and policy makers.
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Affiliation(s)
- Amelie D Mbouna
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon.
| | - Alain T Tamoffo
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon
- Physics Department, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Ernest O Asare
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, USA
| | - Andre Lenouo
- Department of Physics, Faculty of Science, University of Douala, Douala, Cameroon
| | - Clement Tchawoua
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon
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Diouf I, Ndione JA, Gaye AT. Malaria in Senegal: Recent and Future Changes Based on Bias-Corrected CMIP6 Simulations. Trop Med Infect Dis 2022; 7:tropicalmed7110345. [PMID: 36355887 PMCID: PMC9694468 DOI: 10.3390/tropicalmed7110345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/15/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
Malaria is a constant reminder of the climate change impacts on health. Many studies have investigated the influence of climatic parameters on aspects of malaria transmission. Climate conditions can modulate malaria transmission through increased temperature, which reduces the duration of the parasite’s reproductive cycle inside the mosquito. The rainfall intensity and frequency modulate the mosquito population’s development intensity. In this study, the Liverpool Malaria Model (LMM) was used to simulate the spatiotemporal variation of malaria incidence in Senegal. The simulations were based on the WATCH Forcing Data applied to ERA-Interim data (WFDEI) used as a point of reference, and the biased-corrected CMIP6 model data, separating historical simulations and future projections for three Shared Socio-economic Pathways scenarios (SSP126, SSP245, and SSP585). Our results highlight a strong increase in temperatures, especially within eastern Senegal under the SSP245 but more notably for the SSP585 scenario. The ability of the LMM model to simulate the seasonality of malaria incidence was assessed for the historical simulations. The model revealed a period of high malaria transmission between September and November with a maximum reached in October, and malaria results for historical and future trends revealed how malaria transmission will change. Results indicate a decrease in malaria incidence in certain regions of the country for the far future and the extreme scenario. This study is important for the planning, prioritization, and implementation of malaria control activities in Senegal.
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Affiliation(s)
- Ibrahima Diouf
- Laboratoire de Physique de l’Atmosphère et de l’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de l’Université Cheikh Anta Diop (UCAD), BP 5085, Dakar-Fann, Dakar 10700, Senegal
- Correspondence: ; Tel.: +221-78-381-69-87
| | | | - Amadou Thierno Gaye
- Laboratoire de Physique de l’Atmosphère et de l’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de l’Université Cheikh Anta Diop (UCAD), BP 5085, Dakar-Fann, Dakar 10700, Senegal
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Baharom M, Soffian SSS, Peng CS, Baharudin MH, Mirza U, Madrim MF, Jeffree MS, Rahim SSSA, Hassan MR. Projecting Malaria Incidence Based on Climate Change Modeling Approach: A Systematic Review. Open Access Maced J Med Sci 2022. [DOI: 10.3889/oamjms.2022.10141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND: Climate change will affect the transmission of malaria by shifting the geographical space of the vector.
AIM: The review aims to examine the climate change modeling approach and climatic variables used for malaria projection.
METHODS: Articles were systematically searched from four databases, Scopus, Web of Science, PubMed, and SAGE. The PICO concept was used for formulation search and PRISMA approach to identify the final articles.
RESULTS: A total of 27 articles were retrieved and reviewed. There were six climate factors identified in this review: Temperature, rainfall/precipitation, humidity, wind, solar radiation, and climate change scenarios. Modeling approaches used to project future malarial trend includes mathematical and computational approach.
CONCLUSION: This review provides robust evidence of an association between the impact of climate change and malaria incidence. Prediction on seasonal patterns would be useful for malaria surveillance in public health prevention and mitigation strategies.
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Cissoko M, Sagara I, Landier J, Guindo A, Sanogo V, Coulibaly OY, Dembélé P, Dieng S, Bationo CS, Diarra I, Magassa MH, Berthé I, Katilé A, Traoré D, Dessay N, Gaudart J. Sub-national tailoring of seasonal malaria chemoprevention in Mali based on malaria surveillance and rainfall data. Parasit Vectors 2022; 15:278. [PMID: 35927679 PMCID: PMC9351140 DOI: 10.1186/s13071-022-05379-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/28/2022] [Indexed: 11/16/2022] Open
Abstract
Background In malaria endemic countries, seasonal malaria chemoprevention (SMC) interventions are performed during the high malaria transmission in accordance with epidemiological surveillance data. In this study we propose a predictive approach for tailoring the timing and number of cycles of SMC in all health districts of Mali based on sub-national epidemiological surveillance and rainfall data. Our primary objective was to select the best of two approaches for predicting the onset of the high transmission season at the operational scale. Our secondary objective was to evaluate the number of malaria cases, hospitalisations and deaths in children under 5 years of age that would be prevented annually and the additional cost that would be incurred using the best approach. Methods For each of the 75 health districts of Mali over the study period (2014–2019), we determined (1) the onset of the rainy season period based on weekly rainfall data; (ii) the onset and duration of the high transmission season using change point analysis of weekly incidence data; and (iii) the lag between the onset of the rainy season and the onset of the high transmission. Two approaches for predicting the onset of the high transmission season in 2019 were evaluated. Results In the study period (2014–2019), the onset of the rainy season ranged from week (W) 17 (W17; April) to W34 (August). The onset of the high transmission season ranged from W25 (June) to W40 (September). The lag between these two events ranged from 5 to 12 weeks. The duration of the high transmission season ranged from 3 to 6 months. The best of the two approaches predicted the onset of the high transmission season in 2019 to be in June in two districts, in July in 46 districts, in August in 21 districts and in September in six districts. Using our proposed approach would prevent 43,819 cases, 1943 hospitalisations and 70 deaths in children under 5 years of age annually for a minimal additional cost. Our analysis shows that the number of cycles of SMC should be changed in 36 health districts. Conclusion Adapting the timing of SMC interventions using our proposed approach could improve the prevention of malaria cases and decrease hospitalisations and deaths. Future studies should be conducted to validate this approach. Graphical Abstract ![]()
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Affiliation(s)
- Mady Cissoko
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali. .,INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France. .,Direction Régionale de la Santé de Tombouctou, 59, Tombouctou, Mali.
| | - Issaka Sagara
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali.,INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France
| | - Jordi Landier
- INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France
| | - Abdoulaye Guindo
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali.,INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France
| | - Vincent Sanogo
- Programme National de Lutte contre le Paludisme (PNLP Mali), 233, Bamako, Mali
| | - Oumou Yacouba Coulibaly
- Direction Générale de la Santé et Hygiène Publique, Sous-Direction Lutte Contre la Maladie (DGSHP-SDLM), 233, Bamako, Mali
| | - Pascal Dembélé
- Programme National de Lutte contre le Paludisme (PNLP Mali), 233, Bamako, Mali
| | - Sokhna Dieng
- INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France
| | | | - Issa Diarra
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali
| | - Mahamadou H Magassa
- Programme National de Lutte contre le Paludisme (PNLP Mali), 233, Bamako, Mali
| | - Ibrahima Berthé
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali
| | - Abdoulaye Katilé
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali.,INSERM, IRD, ISSPAM, UM1252, Aix-Marseille University, 13005, Marseille, France
| | - Diahara Traoré
- Programme National de Lutte contre le Paludisme (PNLP Mali), 233, Bamako, Mali
| | - Nadine Dessay
- ESPACE-DEV, UMR228, IRD/UM/UR/UG/UA, Institut de Recherche Pour le Développement (IRD) France, 34093, Montpellier, France
| | - Jean Gaudart
- Malaria Research and Training Centre Ogobara K. Doumbo (MRTC-OKD), FMOS-FAPH, Mali-NIAID-ICER, Université Des Sciences, Des Techniques Et Des Technologies de Bamako, 1805, Bamako, Mali.,APHM, INSERM, SESSTIM, ISSPAM, Hop Timone, BioSTIC, Biostatistic & ICT, Aix-Marseille University, 13005, Marseille, France
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Aung PL, Soe MT, Oo TL, Aung KT, Lin KK, Thi A, Menezes L, Parker DM, Cui L, Kyaw MP. Spatiotemporal dynamics of malaria in Banmauk Township, Sagaing region of Northern Myanmar: characteristics, trends, and risk factors. BMC Infect Dis 2022; 22:653. [PMID: 35902825 PMCID: PMC9331130 DOI: 10.1186/s12879-022-07634-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 07/19/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While national malaria incidence has been declining in Myanmar, some subregions within the nation continue to have high burdens of malaria morbidity and mortality. This study assessed the malaria situation in one of these regions, Banmauk Township, located near the Myanmar-India border. Our goal was to provide a detailed description of the malaria epidemiology in this township and to provide some evidence-based recommendations to formulate a strategy for reaching the national malaria elimination plan. Banmauk consistently has one of the highest malaria burdens in Myanmar. METHODS With the implementation of strengthened malaria control and surveillance activities after the endorsement of a national malaria elimination plan in 2015, detailed incidence data were obtained for 2016-2018 for Banmauk Township. The data include patient demographics, parasite species, disease severity, and disease outcome. Data were analyzed to identify characteristics, trends, distribution, and risk factors. RESULTS During 2016-2018, 2,402 malaria cases were reported, with Plasmodium falciparum accounting for 83.4% of infections. Both P. falciparum and P. vivax were transmitted more frequently during the rainy season (May-October). Despite intensified control, the annual parasite incidence rate (API) in 2017 (11.0) almost doubled that in 2016 (6.5). In total, 2.5% (59/2042) of the cases, of which 54 P. falciparum and 5 P. vivax, were complicated cases, resulting in 5 deaths. Malaria morbidity was high in children < 15 years and accounted for 33.4% of all cases and about 47% of the complicated cases. Older age groups and males living with poor transportation conditions were more likely to test positive especially in rainy and cold seasons. Despite the clear seasonality of malaria, severe cases were found among young children even more common in the dry season, when malaria incidence was low. CONCLUSIONS Despite the declining trend, the malaria burden remained high in Banmauk Township. Our study also documented severe cases and deaths from both falciparum and vivax malaria. P. falciparum remained the predominant parasite species, demanding increased efforts to achieve the goal of elimination of P. falciparum by 2025. As P. falciparum cases decreased, the proportion of cases attributable to P. vivax increased. In order to eliminate malaria, it will likely be important to increasingly target this species as well.
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Affiliation(s)
| | - Myat Thu Soe
- Myanmar Health Network Organization, Yangon, Myanmar
| | - Thit Lwin Oo
- Myanmar Health Network Organization, Yangon, Myanmar
| | - Kyaw Thu Aung
- Township Health Department, Banmauk Township, Sagaing, Myanmar
| | - Kyaw Kyaw Lin
- Township Health Department, Banmauk Township, Sagaing, Myanmar
| | - Aung Thi
- Department of Public Health, Ministry of Health, NayPyiTaw, Myanmar
| | - Lynette Menezes
- Division of Infectious Diseases and International Medicine, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL, 33612, USA
| | - Daniel M Parker
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, USA.
| | - Liwang Cui
- Division of Infectious Diseases and International Medicine, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL, 33612, USA.
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Thiam F, Diop G, Coulonges C, Derbois C, Mbengue B, Thiam A, Nguer CM, Zagury JF, Deleuze JF, Dieye A. G6PD and HBB polymorphisms in the Senegalese population: prevalence, correlation with clinical malaria. PeerJ 2022; 10:e13487. [PMID: 35811813 PMCID: PMC9266585 DOI: 10.7717/peerj.13487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/03/2022] [Indexed: 01/24/2023] Open
Abstract
Background Host genetic factors contribute to the variability of malaria phenotypes and can allow a better understanding of mechanisms involved in susceptibility and/or resistance to Plasmodium falciparum infection outcomes. Several genetic polymorphisms were reported to be prevalent among populations living in tropical malaria-endemic regions and induce protection against malaria. The present study aims to investigate the prevalence of HBB (chr11) and G6PD (chrX) deficiencies polymorphisms among Senegalese populations and their associations with the risk for severe Plasmodium falciparum malaria occurrence. Methods We performed a retrospective study with 437 samples, 323 patients recruited in hospitals located in three different endemic areas where malaria episodes were confirmed and 114 free malaria controls. The patients enrolled were classified into two groups: severe malaria (SM) (153 patients) and uncomplicated malaria (UM) (170 patients). PCR and DNA sequencing assessed host genetic polymorphisms in HBB and G6PD. Using a multivariate regression and additive model, estimates of the impact of human HBB and G6PD polymorphisms on malaria incidence were performed. Results Six frequent SNPs with minor allele frequencies (MAF) > 3% were detected in the HBB gene (rs7946748, rs7480526, rs10768683, rs35209591, HbS (rs334) and rs713040) and two in the G6PD gene (rs762515 and rs1050828 (G6PD-202 G > A). Analysis of selected HbS polymorphism showed significant association with protective effect against severe malaria with a significant p-value = 0.033 (OR 0.38, 95% CI [0.16-0.91]) for SM vs. UM comparison. Surprisingly, our study did not identify the protective effect of variant HbC polymorphism against severe malaria. Finally, we found some of the polymorphisms, like HbS (rs334), are associated with age and biological parameters like eosinophils, basophils, lymphocytes etc. Conclusion Our data report HBB and G6PD polymorphisms in the Senegalese population and their correlation with severe/mild malaria and outcome. The G6PD and HBB deficiencies are widespread in West Africa endemic malaria regions such as The Gambia, Mali, and Burkina Faso. The study shows the critical role of genetic factors in malaria outcomes. Indeed, genetic markers could be good tools for malaria endemicity prognosis.
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Affiliation(s)
- Fatou Thiam
- Groupe de Recherche Biotechnologie Appliquée et Bioprocédés Environnementaux (GRBA-BE), Laboratoire Eau, Energie, Environnement et Procédés Industriels (LE3PI), Département de Génie Chimique et Biologie Appliquée, Ecole Supérieure Polytechnique, Université Cheikh Anta DIOP de Dakar, Dakar Fann, Dakar, Sénégal
| | - Gora Diop
- Unité Postulante de Biologie Génétique, Génomique et Bio-informatique (G2B), Département de Biologie Animale, Faculté des Sciences et Techniques, Université Cheikh Anta DIOP, Avenue Cheikh Anta DIOP, Dakar Fann, Dakar, Sénégal,Pole d’Immunophysiopathologie & Maladies Infectieuses (IMI), Institut Pasteur de Dakar, Dakar, Sénégal
| | - Cedric Coulonges
- Equipe GBA «Génomique, Bioinformatique & Applications », Conservatoire National des Arts et Métiers, Paris, France
| | - Céline Derbois
- CEA, Centre National de Recherche en Génomique Humaine, Université Paris-Saclay, Evry, France
| | - Babacar Mbengue
- Service d’Immunologie, Faculté de Médecine, de Pharmacie et d’Odontostomatologie, Université Cheikh Anta DIOP, Dakar, Sénégal
| | - Alassane Thiam
- Pole d’Immunophysiopathologie & Maladies Infectieuses (IMI), Institut Pasteur de Dakar, Dakar, Sénégal
| | - Cheikh Momar Nguer
- Groupe de Recherche Biotechnologie Appliquée et Bioprocédés Environnementaux (GRBA-BE), Laboratoire Eau, Energie, Environnement et Procédés Industriels (LE3PI), Département de Génie Chimique et Biologie Appliquée, Ecole Supérieure Polytechnique, Université Cheikh Anta DIOP de Dakar, Dakar Fann, Dakar, Sénégal
| | - Jean Francois Zagury
- Equipe GBA «Génomique, Bioinformatique & Applications », Conservatoire National des Arts et Métiers, Paris, France
| | - Jean-Francois Deleuze
- CEA, Centre National de Recherche en Génomique Humaine, Université Paris-Saclay, Evry, France
| | - Alioune Dieye
- Service d’Immunologie, Faculté de Médecine, de Pharmacie et d’Odontostomatologie, Université Cheikh Anta DIOP, Dakar, Sénégal
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Assessment of Climate-Driven Variations in Malaria Transmission in Senegal Using the VECTRI Model. ATMOSPHERE 2022. [DOI: 10.3390/atmos13030418] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Several vector-borne diseases, such as malaria, are sensitive to climate and weather conditions. When unusual conditions prevail, for example, during periods of heavy rainfall, mosquito populations can multiply and trigger epidemics. This study, which consists of better understanding the link between malaria transmission and climate factors at a national level, aims to validate the VECTRI model (VECtor borne disease community model of ICTP, TRIeste) in Senegal. The VECTRI model is a grid-distributed dynamical model that couples a biological model for the vector and parasite life cycles to a simple compartmental Susceptible-Exposed-Infectious-Recovered (SEIR) representation of the disease progression in the human host. In this study, a VECTRI model driven by reanalysis data (ERA-5) was used to simulate malaria parameters, such as the entomological inoculation rate (EIR) in Senegal. Observed malaria data from the National Malaria Control Program in Senegal (PNLP/Programme National de Lutte contre le Paludisme au Senegal) and outputs from the climate data used in this study were compared. The findings highlight the unimodal shape of temporal malaria occurrence, and the seasonal malaria transmission contrast is closely linked to the latitudinal variation of the rainfall, showing a south–north gradient over Senegal. This study showed that the peak of malaria takes place from September to October, with a lag of about one month from the peak of rainfall in Senegal. There is an agreement between observations and simulations about decreasing malaria cases on time. These results indicate that the southern area of Senegal is at the highest risk of malaria spread outbreaks. The findings in the paper are expected to guide community-based early-warning systems and adaptation strategies in Senegal, which will feed into the national malaria prevention, response, and care strategies adapted to the needs of local communities.
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Faye M, Dème A, Diongue AK, Diouf I. Impact of different heat wave definitions on daily mortality in Bandafassi, Senegal. PLoS One 2021; 16:e0249199. [PMID: 33819272 PMCID: PMC8021182 DOI: 10.1371/journal.pone.0249199] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 03/12/2021] [Indexed: 11/19/2022] Open
Abstract
Objective The aim of this study is to find the most suitable heat wave definition among 15 different ones and to evaluate its impact on total, age-, and gender-specific mortality for Bandafassi, Senegal. Methods Daily weather station data were obtained from Kedougou situated at 17 km from Bandafassi from 1973 to 2012. Poisson generalized additive model (GAM) and distributed lag non-linear model (DLNM) are used to investigate the effect of heat wave on mortality and to evaluate the nonlinear association of heat wave definitions at different lag days, respectively. Results Heat wave definitions, based on three or more consecutive days with both daily minimum and maximum temperatures greater than the 90th percentile, provided the best model fit. A statistically significant increase in the relative risk (RRs 1.4 (95% Confidence Interval (CI): 1.2–1.6), 1.7 (95% CI: 1.5–1.9), 1.21 (95% CI: 1.08–1.3), 1.2 (95% CI: 1.04–1.5), 1.5 (95% CI: 1.3–1.8), 1.4 (95% CI: 1.2–1.5), 1.5 (95% CI: 1.07–1.6), and 1.5 (95% CI: 1.3–1.8)) of total mortality was observed for eight definitions. By using the definition based on the 90th percentile of minimum and maximum temperature with a 3-day duration, we also found that females and people aged ≥ 55 years old were at higher risks than males and other different age groups to heat wave related mortality. Conclusion The impact of heat waves was associated with total-, age-, gender-mortality. These results are expected to be useful for decision makers who conceive of public health policies in Senegal and elsewhere. Climate parameters, including temperatures and humidity, could be used to forecast heat wave risks as an early warning system in the area where we conduct this research. More broadly, our findings should be highly beneficial to climate services, researchers, clinicians, end-users and decision-makers.
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Affiliation(s)
- Mbaye Faye
- LERSTAD—UFR Sciences Appliquées et de Technologies, Université Gaston Berger de Saint-Louis, Saint-Louis, Sénégal
- * E-mail:
| | - Abdoulaye Dème
- LSAO—UFR Sciences Appliquées et de Technologies, Université Gaston Berger de Saint-Louis, Saint-Louis, Sénégal
| | - Abdou Kâ Diongue
- LERSTAD—UFR Sciences Appliquées et de Technologies, Université Gaston Berger de Saint-Louis, Saint-Louis, Sénégal
| | - Ibrahima Diouf
- NOAA Center for Weather and Climate Prediction Climate Prediction Center College Park, Maryland, United States of America
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Neto JM, Mellinger S, Halupka L, Marzal A, Zehtindjiev P, Westerdahl H. Seasonal dynamics of haemosporidian (Apicomplexa, Haemosporida) parasites in house sparrows Passer domesticus at four European sites: comparison between lineages and the importance of screening methods. Int J Parasitol 2020; 50:523-532. [PMID: 32422301 PMCID: PMC7306154 DOI: 10.1016/j.ijpara.2020.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 03/02/2020] [Accepted: 03/27/2020] [Indexed: 01/09/2023]
Abstract
Haemosporidae prevalence and diversity in house sparrows decreased with increasing latitude. The nested PCR method underestimates co-infections and biases results. Seasonal dynamics varied between sites, lineages, species and genera. Seasonality of single lineages (P_SGS1) also varied between sites. Unexpectedly, seasonality was greatest at the southernmost site.
Infectious diseases often vary seasonally in a predictable manner, and seasonality may be responsible for geographical differences in prevalence. In temperate regions, vector-borne parasites such as malaria are expected to evolve lower virulence and a time-varying strategy to invest more in transmission when vectors are available. A previous model of seasonal variation of avian malaria described a double peak in prevalence of Plasmodium parasites in multiple hosts resulting from spring relapses and transmission to susceptible individuals in summer. However, this model was rejected by a study describing different patterns of seasonal variation of two Plasmodium spp. at the same site, with the double peak only apparent when these species were combined. Here, we assessed the seasonal variation in prevalence of haemosporidian parasites (Plasmodium, Haemoproteus and Leucocytozoon) in house sparrows (Passer domesticus) sampled across 1 year at four temperate European sites spanning a latitudinal range of 17°. We showed that parasite prevalence and diversity decreased with increasing latitude, but the parasite communities differed between sites, with only one Plasmodium lineage (P_SGS1) occurring at all sites. Moreover, the nested PCR method commonly used to detect and identify haemosporidian parasites strongly underestimated co-infections of Haemoproteus and Plasmodium, significantly biasing the pattern of seasonal variation, so additional molecular methods were used. Finally, we showed that: (i) seasonal variation in prevalence of haemosporidian parasites varied between study sites and parasite lineages/species/genera, describing further cases where the double peak model is not met; (ii) the seasonal dynamics of single lineages (P_SGS1) varied between sites; and (iii) unexpectedly, seasonality was greatest at the southernmost site, a pattern that was mostly driven by lineage H_PADOM05. Limitations of the genotyping methods and consequences of pooling (parasite lineages, sites and years) in studies of haemosporidian parasites are discussed and recommendations proposed, since these actions may obscure the patterns of prevalence and limit ecological inferences.
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Affiliation(s)
- Júlio Manuel Neto
- Molecular Ecology and Evolution Lab, Department of Biology, Ecology Building, SE-223 62 Lund, Sweden.
| | - Samantha Mellinger
- Molecular Ecology and Evolution Lab, Department of Biology, Ecology Building, SE-223 62 Lund, Sweden
| | - Lucyna Halupka
- Ornithological Station, Wrocław University, Sienkiewicza 21, 50-335 Wrocław, Poland
| | - Alfonso Marzal
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, E-06006 Badajoz, Spain
| | - Pavel Zehtindjiev
- Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Helena Westerdahl
- Molecular Ecology and Evolution Lab, Department of Biology, Ecology Building, SE-223 62 Lund, Sweden
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Diallo MA, Badiane AS, Diongue K, Sakandé L, Ndiaye M, Seck MC, Ndiaye D. A twenty-eight-year laboratory-based retrospective trend analysis of malaria in Dakar, Senegal. PLoS One 2020; 15:e0231587. [PMID: 32413069 PMCID: PMC7228107 DOI: 10.1371/journal.pone.0231587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/27/2020] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Health facility-based records offer a rich source of information to understand trends and changes in malaria cases over time. This study is aimed at determining the changes in malaria occurrence over the last 28 years, from 1989 to 2016 in Dakar, Senegal. METHODS Laboratory suspected and confirmed malaria records from 1989 to 2016 were reviewed from the laboratory registers of the Laboratory of Parasitology and Mycology of Aristide Le Dantec Hospital. Interrupted time series (ITS) analysis was used to estimate the changes by comparing malaria cases post-intervention (2006-2016) with that of the pre-intervention (1989-2005) period. RESULTS A total of 5,876 laboratory confirmed malaria cases were reported out of 29,852 tested cases, with total slide positivity rate (SPR) of 19.7%. Malaria case counts exhibited a fluctuating trend with major peaks occurring in the years 1995 and 2003 with SPR of 42.3% and 42.5%, respectively. Overall, a remarkable decline in the total number of laboratory confirmed malaria cases was observed over the last 28 years. P. falciparum was almost the only reported species, accounting for 99.98% of cases. The highest SPR was observed in the age group of under five years during the pre-intervention period while this shifted to the age group of 6-15 years old for the subsequent years. Two major malaria peak seasons were observed: one in September during the pre-intervention period and the other in November for the post-intervention period. The ITS analysis showed a dramatic decline of 83.6% in SPR following the scale-up of interventions in 2006. CONCLUSION A remarkable decline in laboratory confirmed malaria cases in Dakar over 28 years was observed. The period of rapid decline in malaria SPR coincided with the scale-up in interventions beginning in 2006 with the introduction of ACTs, followed by the widespread introduction in 2008 of bed nets treated with insecticides. Robust surveillance data should be maintained in the context of malaria elimination efforts.
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Affiliation(s)
- Mamadou Alpha Diallo
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
- * E-mail:
| | | | - Khadim Diongue
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
| | - Linda Sakandé
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
| | - Mouhamadou Ndiaye
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
| | - Mame Cheikh Seck
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
| | - Daouda Ndiaye
- Department of Parasitology, Cheikh Anta Diop University, Dakar, Senegal
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Diouf I, Rodriguez Fonseca B, Caminade C, Thiaw WM, Deme A, Morse AP, Ndione JA, Gaye AT, Diaw A, Ndiaye MKN. Climate Variability and Malaria over West Africa. Am J Trop Med Hyg 2020; 102:1037-1047. [PMID: 32189612 PMCID: PMC7204584 DOI: 10.4269/ajtmh.19-0062] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 02/01/2020] [Indexed: 01/24/2023] Open
Abstract
Malaria is a major public health problem in West Africa. Previous studies have shown that climate variability significantly affects malaria transmission. The lack of continuous observed weather station data and the absence of surveillance data for malaria over long periods have led to the use of reanalysis data to drive malaria models. In this study, we use the Liverpool Malaria Model (LMM) to simulate spatiotemporal variability of malaria in West Africa using daily rainfall and temperature from the following: Twentieth Century Reanalysis (20th CR), National Center for Environmental Prediction (NCEP), European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Reanalysis of the Twentieth Century (ERA20C), and interim ECMWF Re-Analysis (ERA-Interim). Malaria case data from the national surveillance program in Senegal are used for model validation between 2001 and 2016. The warm temperatures found over the Sahelian fringe of West Africa can lead to high malaria transmission during wet years. The rainfall season peaks in July to September over West Africa and Senegal, and the malaria season lasts from September to November, about 1-2 months after the rainfall peak. The long-term trends exhibit interannual and decadal variabilities. The LMM shows acceptable performance in simulating the spatial distribution of malaria incidence. However, some discrepancies are found. These results are useful for decision-makers who plan public health and control measures in affected West African countries. The study would have substantial implications for directing malaria surveillance activities and health policy. In addition, this malaria modeling framework could lead to the development of an early warning system for malaria in West Africa.
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Affiliation(s)
- Ibrahima Diouf
- NOAA Center for Weather and Climate Prediction, College Park, Maryland
- Laboratoire de Physique de L’Atmosphère et de L’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de L’Université Cheikh Anta Diop, Dakar, Sénégal
| | - Belén Rodriguez Fonseca
- Department of Geophysics and Meteorology, Universidad Complutense de Madrid, Madrid, Spain
- Instituto de Geociencias IGEO, CSIC-UCM, Agencia Estatal del Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Cyril Caminade
- Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- National Institute for Health Research [M1] (NIHR), Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, United Kingdom
| | - Wassila M. Thiaw
- NOAA Center for Weather and Climate Prediction, College Park, Maryland
| | - Abdoulaye Deme
- Unité de Formation et de Recherche de Sciences Appliquées et de Technologie, Université Gaston Berger, Saint Louis, Sénégal
| | - Andrew P. Morse
- National Institute for Health Research [M1] (NIHR), Health Protection Research Unit in Emerging and Zoonotic Infections, Liverpool, United Kingdom
- Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, United Kingdom
| | | | - Amadou Thierno Gaye
- Laboratoire de Physique de L’Atmosphère et de L’Océan-Siméon Fongang, Ecole Supérieure Polytechnique de L’Université Cheikh Anta Diop, Dakar, Sénégal
| | - Anta Diaw
- General Direction of Public Health, Ministry of Health and Social Action, Dakar, Senegal
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Mbouna AD, Tompkins AM, Lenouo A, Asare EO, Yamba EI, Tchawoua C. Modelled and observed mean and seasonal relationships between climate, population density and malaria indicators in Cameroon. Malar J 2019; 18:359. [PMID: 31707994 PMCID: PMC6842545 DOI: 10.1186/s12936-019-2991-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 10/31/2019] [Indexed: 11/17/2022] Open
Abstract
Background A major health burden in Cameroon is malaria, a disease that is sensitive to climate, environment and socio-economic conditions, but whose precise relationship with these drivers is still uncertain. An improved understanding of the relationship between the disease and its drivers, and the ability to represent these relationships in dynamic disease models, would allow such models to contribute to health mitigation and adaptation planning. This work collects surveys of malaria parasite ratio and entomological inoculation rate and examines their relationship with temperature, rainfall, population density in Cameroon and uses this analysis to evaluate a climate sensitive mathematical model of malaria transmission. Methods Co-located, climate and population data is compared to the results of 103 surveys of parasite ratio (PR) covering 18,011 people in Cameroon. A limited set of campaigns which collected year-long field-surveys of the entomological inoculation rate (EIR) are examined to determine the seasonality of disease transmission, three of the study locations are close to the Sanaga and Mefou rivers while others are not close to any permanent water feature. Climate-driven simulations of the VECTRI malaria model are evaluated with this analysis. Results The analysis of the model results shows the PR peaking at temperatures of approximately 22 °C to 26 °C, in line with recent work that has suggested a cooler peak temperature relative to the established literature, and at precipitation rates at 7 mm day−1, somewhat higher than earlier estimates. The malaria model is able to reproduce this broad behaviour, although the peak occurs at slightly higher temperatures than observed, while the PR peaks at a much lower rainfall rate of 2 mm day−1. Transmission tends to be high in rural and peri-urban relative to urban centres in both model and observations, although the model is oversensitive to population which could be due to the neglect of population movements, and differences in hydrological conditions, housing quality and access to healthcare. The EIR follows the seasonal rainfall with a lag of 1 to 2 months, and is well reproduced by the model, while in three locations near permanent rivers the annual cycle of malaria transmission is out of phase with rainfall and the model fails. Conclusion Malaria prevalence is maximum at temperatures of 24 to 26 °C in Cameroon and rainfall rates of approximately 4 to 6 mm day−1. The broad relationships are reproduced in a malaria model although prevalence is highest at a lower rainfall maximum of 2 mm day−1. In locations far from water bodies malaria transmission seasonality closely follows that of rainfall with a lag of 1 to 2 months, also reproduced by the model, but in locations close to a seasonal river the seasonality of malaria transmission is reversed due to pooling in the transmission to the dry season, which the model fails to capture.
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Affiliation(s)
- Amelie D Mbouna
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé́ I, Yaoundé, Cameroon. .,Earth System Physics, Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy.
| | - Adrian M Tompkins
- Earth System Physics, Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy
| | - Andre Lenouo
- Department of Physics, Faculty of Science, University of Douala, Douala, Cameroon
| | - Ernest O Asare
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, USA
| | - Edmund I Yamba
- Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Clement Tchawoua
- Laboratory for Environmental Modelling and Atmospheric Physics (LEMAP), Department of Physics, Faculty of Science, University of Yaoundé́ I, Yaoundé, Cameroon
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Abstract
Early warning systems to predict infectious disease outbreaks have been identified as a key adaptive response to climate change. Warming, climate variability and extreme weather events associated with climate change are expected to drive an increase in frequency and intensity of mosquito-borne disease (MBD) outbreaks globally. In Canada, this will mean an increased risk of endemic and emerging MBD outbreaks such as West Nile virus and other MBDs. The availability of timely information on the risk of impending MBD outbreaks has important public health implications, by allowing implementation of mosquito control measures and targeted communications regarding the need for increased personal protective measures-before an outbreak occurs. In Canada, both mechanistic and statistical weather-based models have been developed to predict West Nile virus outbreaks. These include models for different species of mosquitoes that transmit West Nile virus in different geographical areas of Canada. Although initial results have been promising, further validation and assessment of forecasting skill are needed before wide scale implementation. Weather-based forecasting for other emerging MBDs in Canada, such as Eastern equine encephalitis, may also be feasible.
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