1
|
Villena OC, Arab A, Lippi CA, Ryan SJ, Johnson LR. Influence of environmental, geographic, socio-demographic, and epidemiological factors on presence of malaria at the community level in two continents. Sci Rep 2024; 14:16734. [PMID: 39030306 PMCID: PMC11271557 DOI: 10.1038/s41598-024-67452-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Accepted: 07/11/2024] [Indexed: 07/21/2024] Open
Abstract
The interactions of environmental, geographic, socio-demographic, and epidemiological factors in shaping mosquito-borne disease transmission dynamics are complex and changeable, influencing the abundance and distribution of vectors and the pathogens they transmit. In this study, 27 years of cross-sectional malaria survey data (1990-2017) were used to examine the effects of these factors on Plasmodium falciparum and Plasmodium vivax malaria presence at the community level in Africa and Asia. Monthly long-term, open-source data for each factor were compiled and analyzed using generalized linear models and classification and regression trees. Both temperature and precipitation exhibited unimodal relationships with malaria, with a positive effect up to a point after which a negative effect was observed as temperature and precipitation increased. Overall decline in malaria from 2000 to 2012 was well captured by the models, as was the resurgence after that. The models also indicated higher malaria in regions with lower economic and development indicators. Malaria is driven by a combination of environmental, geographic, socioeconomic, and epidemiological factors, and in this study, we demonstrated two approaches to capturing this complexity of drivers within models. Identifying these key drivers, and describing their associations with malaria, provides key information to inform planning and prevention strategies and interventions to reduce malaria burden.
Collapse
Affiliation(s)
- Oswaldo C Villena
- The Earth Commons Institute, Georgetown University, Washington, DC, 20057, USA.
| | - Ali Arab
- Department of Mathematics and Statistics, Georgetown University, Washington, DC, 20057, USA
| | - Catherine A Lippi
- Department of Geography, University of Florida, Gainesville, FL, 32611, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Sadie J Ryan
- Department of Geography, University of Florida, Gainesville, FL, 32611, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Leah R Johnson
- Department of Statistics, Virginia Tech, Blacksburg, VA, 24061, USA
- Computational Modeling and Data Analytics, Virginia Tech, Blacksburg, VA, 24061, USA
- Department of Biology, Virginia Tech, Blacksburg, VA, 24061, USA
| |
Collapse
|
2
|
Gbaguidi GJ, Idrissou M, Topanou N, Filho WL, Ketoh GK. Application of advanced very high-resolution radiometer (AVHRR)-based vegetation health indices for modelling and predicting malaria in Northern Benin, West Africa. Malar J 2024; 23:78. [PMID: 38491345 PMCID: PMC10943795 DOI: 10.1186/s12936-024-04879-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/12/2024] [Indexed: 03/18/2024] Open
Abstract
BACKGROUND Vegetation health (VH) is a powerful characteristic for forecasting malaria incidence in regions where the disease is prevalent. This study aims to determine how vegetation health affects the prevalence of malaria and create seasonal weather forecasts using NOAA/AVHRR environmental satellite data that can be substituted for malaria epidemic forecasts. METHODS Weekly advanced very high-resolution radiometer (AVHRR) data were retrieved from the NOAA satellite website from 2009 to 2021. The monthly number of malaria cases was collected from the Ministry of Health of Benin from 2009 to 2021 and matched with AVHRR data. Pearson correlation was calculated to investigate the impact of vegetation health on malaria transmission. Ordinary least squares (OLS), support vector machine (SVM) and principal component regression (PCR) were applied to forecast the monthly number of cases of malaria in Northern Benin. A random sample of proposed models was used to assess accuracy and bias. RESULTS Estimates place the annual percentage rise in malaria cases at 9.07% over 2009-2021 period. Moisture (VCI) for weeks 19-21 predicts 75% of the number of malaria cases in the month of the start of high mosquito activities. Soil temperature (TCI) and vegetation health index (VHI) predicted one month earlier than the start of mosquito activities through transmission, 78% of monthly malaria incidence. CONCLUSIONS SVM model D is more effective than OLS model A in the prediction of malaria incidence in Northern Benin. These models are a very useful tool for stakeholders looking to lessen the impact of malaria in Benin.
Collapse
Affiliation(s)
- Gouvidé Jean Gbaguidi
- West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), Faculty of Human and Social Sciences, Department of Geography, University of Lomé, Lomé, Togo.
- Laboratory of Ecology and Ecotoxicology, Department of Zoology, Faculty of Sciences, University of Lomé, 1BP: 1515, Lomé, Togo.
| | - Mouhamed Idrissou
- West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL), Faculty of Human and Social Sciences, Department of Geography, University of Lomé, Lomé, Togo
- École Polytechnique de Lomé, University of Lomé, Lomé, Togo
| | - Nikita Topanou
- Kaba Laboratory of Chemical Research and Application (LaKReCA), Department of Chemistry, Faculty of Science and Technic of Natitingou, University of Abomey, Abomey, Benin
| | - Walter Leal Filho
- Research and Transfer Centre Sustainability and Climate Change Management, Faculty of Life Sciences, Hamburg University of Applied Sciences, Ulmenliet 20, 21033, Hamburg, Germany
| | - Guillaume K Ketoh
- Laboratory of Ecology and Ecotoxicology, Department of Zoology, Faculty of Sciences, University of Lomé, 1BP: 1515, Lomé, Togo
| |
Collapse
|
3
|
Gbaguidi GJ, Topanou N, Filho WL, Ketoh GK. Towards an intelligent malaria outbreak warning model based intelligent malaria outbreak warning in the northern part of Benin, West Africa. BMC Public Health 2024; 24:450. [PMID: 38347490 PMCID: PMC10863265 DOI: 10.1186/s12889-024-17847-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 01/22/2024] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND Malaria is one of the major vector-borne diseases most sensitive to climatic change in West Africa. The prevention and reduction of malaria are very difficult in Benin due to poverty, economic insatiability and the non control of environmental determinants. This study aims to develop an intelligent outbreak malaria early warning model driven by monthly time series climatic variables in the northern part of Benin. METHODS Climate data from nine rain gauge stations and malaria incidence data from 2009 to 2021 were extracted from the National Meteorological Agency (METEO) and the Ministry of Health of Benin, respectively. Projected relative humidity and temperature were obtained from the coordinated regional downscaling experiment (CORDEX) simulations of the Rossby Centre Regional Atmospheric regional climate model (RCA4). A structural equation model was employed to determine the effects of climatic variables on malaria incidence. We developed an intelligent malaria early warning model to predict the prevalence of malaria using machine learning by applying three machine learning algorithms, including linear regression (LiR), support vector machine (SVM), and negative binomial regression (NBiR). RESULTS Two ecological factors such as factor 1 (related to average mean relative humidity, average maximum relative humidity, and average maximal temperature) and factor 2 (related to average minimal temperature) affect the incidence of malaria. Support vector machine regression is the best-performing algorithm, predicting 82% of malaria incidence in the northern part of Benin. The projection reveals an increase in malaria incidence under RCP4.5 and RCP8.5 over the studied period. CONCLUSION These results reveal that the northern part of Benin is at high risk of malaria, and specific malaria control programs are urged to reduce the risk of malaria.
Collapse
Affiliation(s)
- Gouvidé Jean Gbaguidi
- Department of Geography, West African Science Service Centre On Climate Change and Adapted Land Use (WASCAL), Faculty of Human and Social Sciences, University of Lomé, Lomé, Togo.
- Department of Zoology, Laboratory of Ecology and Ecotoxicology, Faculty of Sciences, University of Lomé, 1BP: 1515, Lomé, Togo.
| | - Nikita Topanou
- Department of Chemistry, Kaba Laboratory of Chemical Research and Application (LaKReCA), Faculty of Science and Technic of Natitingou, University of Abomey, Abomey, Benin
| | - Walter Leal Filho
- Research and Transfer Centre Sustainability and Climate Change Management, Faculty of Life Sciences, Hamburg University of Applied Sciences, Ulmenliet 20, 21033, Hamburg, Germany
| | - Guillaume K Ketoh
- Department of Zoology, Laboratory of Ecology and Ecotoxicology, Faculty of Sciences, University of Lomé, 1BP: 1515, Lomé, Togo
| |
Collapse
|
4
|
Hong H, Eom TH, Trinh TTT, Tuan BD, Park H, Yeo SJ. Identification of breeding habitats and kdr mutations in Anopheles spp. in South Korea. Malar J 2023; 22:381. [PMID: 38104158 PMCID: PMC10724954 DOI: 10.1186/s12936-023-04821-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023] Open
Abstract
BACKGROUND Malaria is still endemic in South Korea. However, limited information is available on the current Anopheles breeding sites and the occurrence of insecticide resistance-associated genetic mutations and their distribution needed to control the malaria vector efficiently. METHODS This study explored breeding sites of Anopheline adults in Gimpo-si, near the demilitarized zone (DMZ) in Gyeonggi-do province, South Korea, from 2022 to 2023. Genetic diversity was investigated based on the internal transcribed spacer (ITS2), cytochrome c oxidase subunit I (COI), and knockdown resistance (kdr) genes of Anopheles mosquitoes. A natural environment associated with the seasonal abundance of Anopheles larvae was characterized. RESULTS Two breeding sites of Anopheles larvae and adults were found at a stream margin or shallow freshwater near the forest in Wolgot-myeon in Gimpo-si without cattle shed within 1 km and in Naega-myeon in Ganghwa-gun with cow shed within 100 m in 2022 and 2023, respectively. Both sites were located between the newly cultivated lands and the forest. Besides, both breeding sites were in the valley at a slight elevation of 60-70 m from ground lands and maintained the shadow all day. Overall, the Wolgot-myeon breeding site showed various Anopheles spp. larvae, including Anopheles sinensis. Naega-myeon, an additional breeding site found in 2023, had Anopheles sineroides larvae, and approximately 59.7% (89/149) of An. sinensis adults inhabited within a 100-m distance. The total collection, including larvae and adults, revealed that An. sinensis, Anopheles pullus, Anopheles kleini, An. sineroides, Anopheles belenrae, and Anopheles lindesayi accounted for 44.2% (118/267), 0.7% (2/267), 0.7% (2/267), 22.1% (59/267), 1.9% (5/267), and 30.3% (81/267), respectively. Furthermore, various kdr mutant genotypes (F/F, C/C, L/F, L/C and F/C) in An. sinensis, and the first kdr allele mutant (L/F1014) in An. belenrae were identified in South Korea. CONCLUSIONS Two breeding sites of Anopheles larvae were studied in Wolgot-myeon and Naega-myeon. Various Anopheles spp. larvae were detected in both habitats, but overall, An. sinensis was the most prevalent adults in both study sites. The occurrence of kdr allele mutant of An. belenrae in South Korea was reported. Rigorous larvae monitoring of Anopheles spp., continuously updating information on Anopheles breeding sites, and understanding the environmental conditions of Anopheles habitats are required to develop an effective malaria control programme in South Korea.
Collapse
Affiliation(s)
- Hyelee Hong
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea
| | - Tae-Hui Eom
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea
| | - Thuy-Tien Thi Trinh
- Department of Tropical Medicine and Parasitology, Medical Research Center, Institute of Endemic Diseases, Seoul National University, Seoul, 03080, Republic of Korea
| | - Bao Duong Tuan
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, 460 Iksan-Daero, Iksan, 54538, Republic of Korea
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, 460 Iksan-Daero, Iksan, 54538, Republic of Korea
| | - Seon-Ju Yeo
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea.
- Department of Tropical Medicine and Parasitology, Medical Research Center, Institute of Endemic Diseases, Seoul National University, Seoul, 03080, Republic of Korea.
| |
Collapse
|
5
|
Pradhan S, Hore S, Roy S, Manna S, Dam P, Mondal R, Ghati A, Biswas T, Shaw S, Sharma S, Singh WS, Maji SK, Roy S, Basu A, Pandey KC, Samanta S, Vashisht K, Dolai TK, Kundu PK, Mitra S, Biswas D, Sadat A, Shokriyan M, Maity AB, Mandal AK, İnce İA. Geo-environmental factors and the effectiveness of mulberry leaf extract in managing malaria. Sci Rep 2023; 13:14808. [PMID: 37684270 PMCID: PMC10491663 DOI: 10.1038/s41598-023-41668-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
Malaria prevalence has become medically important and a socioeconomic impediment for the endemic regions, including Purulia, West Bengal. Geo-environmental variables, humidity, altitude, and land use patterns are responsible for malaria. For surveillance of the endemic nature of Purulia's blocks, statistical and spatiotemporal factors analysis have been done here. Also, a novel approach for the Pf malaria treatment using methanolic leaf extract of Morus alba S1 has significantly reduced the parasite load. The EC50 value (1.852) of the methanolic extract of M. alba S1 with P. falciparum 3D7 strain is close to the EC50 value (0.998) of the standard drug chloroquine with the same chloroquine-sensitive strain. Further studies with an in-silico model have shown successful interaction between DHFR and the phytochemicals. Both 1-octadecyne and oxirane interacted favourably, which was depicted through GC-MS analysis. The predicted binary logistic regression model will help the policy makers for epidemiological surveillance in malaria-prone areas worldwide when substantial climate variables create a circumstance favourable for malaria. From the in vitro and in silico studies, it can be concluded that the methanolic extract of M. alba S1 leaves were proven to have promising antiplasmodial activity. Thus, there is a scope for policy-driven approach for discovering and developing these lead compounds and undermining the rising resistance to the frontline anti-malarial drugs in the world.
Collapse
Affiliation(s)
- Sayantan Pradhan
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
- Hematology Department, Nil Ratan Sircar Medical College and Hospital, Kolkata, 700014, India
| | - Samrat Hore
- Department of Statistics, Tripura University, Agartala, Tripura, 799022, India
| | - Stabak Roy
- Department of Geography and Disaster Management, Tripura University, Agartala, Tripura, 799022, India
| | - Simi Manna
- Department of Bio-Medical Laboratory Science and Management, Vidyasagar University, Midnapore, West Bengal, 721102, India
| | - Paulami Dam
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Rittick Mondal
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Amit Ghati
- Department of Microbiology, Barrackpore Rastraguru Surendranath College, Barrackpore, West Bengal, 700120, India
| | - Trishanjan Biswas
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Subhajit Shaw
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Supriya Sharma
- ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | | | - Suman Kumar Maji
- District Public Health Centre, Deben Mahata Government Medical College and Hospital, Purulia, West Bengal, 723101, India
| | - Sankarsan Roy
- PH and CD Branch, Office of the Chief Medical Officer of Health, Purulia, West Bengal, 723101, India
| | - Aparajita Basu
- Department of Microbiology, University of Calcutta, Kolkata, West Bengal, 700019, India
| | - Kailash C Pandey
- ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Soumadri Samanta
- Advanced Functional Nanomaterials, Energy and Environment Unit, Institute of Nano Science and Technology (INST), Phase X, SAS Nagar, Mohali, Punjab, 160062, India
| | - Kapil Vashisht
- ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Tuphan Kanti Dolai
- Hematology Department, Nil Ratan Sircar Medical College and Hospital, Kolkata, 700014, India
| | - Pratip Kumar Kundu
- Department of Microbiology, Santiniketan Medical College, Gobindapur, Muluk, Bolpur, Birbhum, West Bengal, 731204, India
| | - Saptarshi Mitra
- Department of Geography and Disaster Management, Tripura University, Agartala, Tripura, 799022, India
| | - Debasish Biswas
- Department of Economics, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Abdul Sadat
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India
| | - Masuma Shokriyan
- Department of Medical Microbiology, School of Medicine, Acibadem Mehmet Ali Aydınlar University, 34752, Ataşehir, Istanbul, Turkey
| | - Amit Bikram Maity
- Department of Otorhinolaryngology, Institute of Post Graduate Medical Education and Research (S.S.K.M. Hospital), Kolkata, West Bengal, 700020, India.
| | - Amit Kumar Mandal
- Department of Sericulture, Raiganj University, North Dinajpur, West Bengal, 733134, India.
- Centre for Nanotechnology Sciences, Raiganj University, North Dinajpur, West Bengal, 733134, India.
| | - İkbal Agah İnce
- Department of Medical Microbiology, School of Medicine, Acibadem Mehmet Ali Aydınlar University, 34752, Ataşehir, Istanbul, Turkey.
| |
Collapse
|
6
|
Nigussie TZ, Zewotir TT, Muluneh EK. Seasonal and spatial variations of malaria transmissions in northwest Ethiopia: Evaluating climate and environmental effects using generalized additive model. Heliyon 2023; 9:e15252. [PMID: 37089331 PMCID: PMC10114238 DOI: 10.1016/j.heliyon.2023.e15252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 03/16/2023] [Accepted: 03/31/2023] [Indexed: 04/25/2023] Open
Abstract
The impacts of climate change and environmental predictors on malaria epidemiology remain unclear and not well investigated in the Sub-Sahara African region. This study was aimed to investigate the nonlinear effects of climate and environmental factors on monthly malaria cases in northwest Ethiopia, considering space-time interaction effects. The monthly malaria cases and populations sizes of the 152 districts were obtained from the Amhara public health institute and the central statistical agency of Ethiopia. The climate and environmental data were retrieved from US National Oceanic and Atmospheric Administration. The data were analyzed using a spatiotemporal generalized additive model. The spatial, temporal, and space-time interaction effects had higher contributions in explaining the spatiotemporal distribution of malaria transmissions. Malaria transmission was seasonal, in which a higher number of cases occurred from September to November. The long-term trend of malaria incidence has decreased between 2012 and 2018 and has turned to an increased pattern since 2019. Areas neighborhood to the Abay gorge and Benshangul-Gumuz, South Sudan, and Sudan border have higher spatial effects. Climate and environmental predictors had significant nonlinear effects, in which their effects are not stationary through the ranges of values of variables, and they had a smaller contributions in explaining the variabilities of malaria incidence compared to seasonal, spatial and temporal effects. Effects of climate and environmental predictors were nonlinear and varied across areas, ecology, and landscape of the study sites, which had little contribution to explaining malaria transmission variabilities with an account of space and time dimensions. Hence, exploring and developing an early warning system that predicts the outbreak of malaria transmission would have an essential role in controlling, preventing, and eliminating malaria in areas with lower and higher transmission levels and ultimately lead to the achievement of malaria GTS milestones.
Collapse
Affiliation(s)
- Teshager Zerihun Nigussie
- Department of Statistics, College of Science, Bahir Dar University, Bahir Dar, Ethiopia
- Department of Statistics, Faculty of Natural and Computational Sciences, Debre Tabor University, Debre Tabor, Ethiopia
- Corresponding author. Department of Statistics, College of Science, Bahir Dar University, Bahir Dar, Ethiopia.
| | - Temesgen T. Zewotir
- School of Mathematics, Statistics and Computer Science, College of Agriculture Engineering and Science, University of KwaZulu-Natal, Durban, South Africa
| | - Essey Kebede Muluneh
- School of Public Health, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| |
Collapse
|
7
|
Yamba EI, Fink AH, Badu K, Asare EO, Tompkins AM, Amekudzi LK. Climate Drivers of Malaria Transmission Seasonality and Their Relative Importance in Sub-Saharan Africa. GEOHEALTH 2023; 7:e2022GH000698. [PMID: 36743738 PMCID: PMC9884660 DOI: 10.1029/2022gh000698] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 12/15/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
A new database of the Entomological Inoculation Rate (EIR) was used to directly link the risk of infectious mosquito bites to climate in Sub-Saharan Africa. Applying a statistical mixed model framework to high-quality monthly EIR measurements collected from field campaigns in Sub-Saharan Africa, we analyzed the impact of rainfall and temperature seasonality on EIR seasonality and determined important climate drivers of malaria seasonality across varied climate settings in the region. We observed that seasonal malaria transmission was within a temperature window of 15°C-40°C and was sustained if average temperature was well above 15°C or below 40°C. Monthly maximum rainfall for seasonal malaria transmission did not exceed 600 in west Central Africa, and 400 mm in the Sahel, Guinea Savannah, and East Africa. Based on a multi-regression model approach, rainfall and temperature seasonality were found to be significantly associated with malaria seasonality in all parts of Sub-Saharan Africa except in west Central Africa. Topography was found to have significant influence on which climate variable is an important determinant of malaria seasonality in East Africa. Seasonal malaria transmission onset lags behind rainfall only at markedly seasonal rainfall areas such as Sahel and East Africa; elsewhere, malaria transmission is year-round. High-quality EIR measurements can usefully supplement established metrics for seasonal malaria. The study's outcome is important for the improvement and validation of weather-driven dynamical mathematical malaria models that directly simulate EIR. Our results can contribute to the development of fit-for-purpose weather-driven malaria models to support health decision-making in the fight to control or eliminate malaria in Sub-Saharan Africa.
Collapse
Affiliation(s)
- Edmund I. Yamba
- Department of Meteorology and Climate ScienceKwame Nkrumah University of Science and Technology (KNUST)KumasiGhana
| | - Andreas H. Fink
- Institute of Meteorology and Climate ResearchKarlsruhe Institute of TechnologyKarlsruheGermany
| | - Kingsley Badu
- Department of Theoretical and Applied BiologyKwame Nkrumah University of Science and TechnologyKumasiGhana
| | - Ernest O. Asare
- Department of Epidemiology of Microbial DiseasesYale School of Public HealthYale UniversityNew HavenCTUSA
| | - Adrian M. Tompkins
- International Centre for Theoretical Physics, Earth System PhysicsTriesteItaly
| | - Leonard K. Amekudzi
- Department of Meteorology and Climate ScienceKwame Nkrumah University of Science and Technology (KNUST)KumasiGhana
| |
Collapse
|
8
|
Pourtois JD, Tallam K, Jones I, Hyde E, Chamberlin AJ, Evans MV, Ihantamalala FA, Cordier LF, Razafinjato BR, Rakotonanahary RJL, Tsirinomen'ny Aina A, Soloniaina P, Raholiarimanana SH, Razafinjato C, Bonds MH, De Leo GA, Sokolow SH, Garchitorena A. Climatic, land-use and socio-economic factors can predict malaria dynamics at fine spatial scales relevant to local health actors: Evidence from rural Madagascar. PLOS GLOBAL PUBLIC HEALTH 2023; 3:e0001607. [PMID: 36963091 PMCID: PMC10021226 DOI: 10.1371/journal.pgph.0001607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 01/23/2023] [Indexed: 02/24/2023]
Abstract
While much progress has been achieved over the last decades, malaria surveillance and control remain a challenge in countries with limited health care access and resources. High-resolution predictions of malaria incidence using routine surveillance data could represent a powerful tool to health practitioners by targeting malaria control activities where and when they are most needed. Here, we investigate the predictors of spatio-temporal malaria dynamics in rural Madagascar, estimated from facility-based passive surveillance data. Specifically, this study integrates climate, land-use, and representative household survey data to explain and predict malaria dynamics at a high spatial resolution (i.e., by Fokontany, a cluster of villages) relevant to health care practitioners. Combining generalized linear mixed models (GLMM) and path analyses, we found that socio-economic, land use and climatic variables are all important predictors of monthly malaria incidence at fine spatial scales, via both direct and indirect effects. In addition, out-of-sample predictions from our model were able to identify 58% of the Fokontany in the top quintile for malaria incidence and account for 77% of the variation in the Fokontany incidence rank. These results suggest that it is possible to build a predictive framework using environmental and social predictors that can be complementary to standard surveillance systems and help inform control strategies by field actors at local scales.
Collapse
Affiliation(s)
- Julie D Pourtois
- Biology Department, Stanford University, Stanford, CA, United States of America
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Krti Tallam
- Biology Department, Stanford University, Stanford, CA, United States of America
| | - Isabel Jones
- Biology Department, Stanford University, Stanford, CA, United States of America
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Elizabeth Hyde
- School of Medicine, Stanford University, Stanford, CA, United States of America
| | - Andrew J Chamberlin
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Michelle V Evans
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Felana A Ihantamalala
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, United States of America
- NGO Pivot, Ifanadiana, Madagascar
| | | | | | - Rado J L Rakotonanahary
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, United States of America
- NGO Pivot, Ifanadiana, Madagascar
| | | | | | | | - Celestin Razafinjato
- Programme National de Lutte contre le Paludisme, Ministère de la Santé Publique, Antananarivo, Madagascar
| | - Matthew H Bonds
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, United States of America
- NGO Pivot, Ifanadiana, Madagascar
| | - Giulio A De Leo
- Biology Department, Stanford University, Stanford, CA, United States of America
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, United States of America
| | - Susanne H Sokolow
- Woods Institute for the Environment, Stanford University, Stanford, CA, United States of America
- Marine Science Institute and Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA, United States of America
| | - Andres Garchitorena
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
- NGO Pivot, Ifanadiana, Madagascar
| |
Collapse
|
9
|
Amare A, Eshetu T, Lemma W. Dry-season transmission and determinants of Plasmodium infections in Jawi district, northwest Ethiopia. Malar J 2022; 21:45. [PMID: 35164768 PMCID: PMC8842575 DOI: 10.1186/s12936-022-04068-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 01/30/2022] [Indexed: 11/12/2022] Open
Abstract
Background Malaria remains a serious global public health problem, and continues to have a devastating impact on people’s health worldwide. Continuous monitoring and evaluation of current malaria transmission status in different seasons is a mainstay for the success of ongoing intervention strategies for malaria. The purpose of this study was to assess the dry-season transmission and determinants of malaria in Jawi district, northwest Ethiopia. Methods A community-based cross-sectional study was conducted from January 13 to February 11, 2020; among selected Kebeles in the Jawi district. A multistage sampling technique was used in this study. Random and systematic sampling techniques were carried out to select Kebeles and each household, respectively. Light microscopy and CareStart™ Malaria HRP2/pLDH (Pf/Pv) Combo RDT were implemented to determine the prevalence of malaria. Moreover, associated risk factors in the prevalence of malaria were assessed by using a bivariate and multivariate logistic regression model. Results A total of 219 study participants were enrolled in this study. Of the total enrolled individuals, malaria cases were found among 36 individuals with a positivity rate of 16.4% (95% CI 11.4–21.5). Plasmodium falciparum was the predominant species with an estimated prevalence of 87.0% in the study areas. Interrupted utilization of ITN (AOR = 4.411, 95% CI 1.401–13.880), using over 3 years older ITNs (AOR = 9.622, 95% CI 1.881–49.214), travel history (AOR = 12.703, 95% CI 2.441–66.114), living in a house with holes on the wall (AOR = 3.811, 95% CI 1.010–14.384), and living in a house with an eave (AOR = 4.23, 95% CI 1.065–16.801) significantly increased the probability of malaria positivity rate. Conclusion Malaria is still an important public health burden among individuals in the Jawi district. Interrupted utilization of ITNs, using over 3 years older ITNs, living in a house with holes on the wall, living in a house with an eave, and travel history were identified as the risk factors of malaria. Therefore, the District health office and Health extension workers should promote daily utilization of good ITNs and improve housing conditions to reduce malaria prevalence.
Collapse
|
10
|
Larson PS, Eisenberg JNS, Berrocal VJ, Mathanga DP, Wilson ML. An urban-to-rural continuum of malaria risk: new analytic approaches characterize patterns in Malawi. Malar J 2021; 20:418. [PMID: 34689786 PMCID: PMC8543962 DOI: 10.1186/s12936-021-03950-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 10/12/2021] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND The urban-rural designation has been an important risk factor in infectious disease epidemiology. Many studies rely on a politically determined dichotomization of rural versus urban spaces, which fails to capture the complex mosaic of infrastructural, social and environmental factors driving risk. Such evaluation is especially important for Plasmodium transmission and malaria disease. To improve targeting of anti-malarial interventions, a continuous composite measure of urbanicity using spatially-referenced data was developed to evaluate household-level malaria risk from a house-to-house survey of children in Malawi. METHODS Children from 7564 households from eight districts throughout Malawi were tested for presence of Plasmodium parasites through finger-prick blood sampling and slide microscopy. A survey questionnaire was administered and latitude and longitude coordinates were recorded for each household. Distances from households to features associated with high and low levels of development (health facilities, roads, rivers, lakes) and population density were used to produce a principal component analysis (PCA)-based composite measure for all centroid locations of a fine geo-spatial grid covering Malawi. Regression methods were used to test associations of the urbanicity measure against Plasmodium infection status and to predict parasitaemia risk for all locations in Malawi. RESULTS Infection probability declined with increasing urbanicity. The new urbanicity metric was more predictive than either a governmentally defined rural/urban dichotomous variable or a population density variable. One reason for this was that 23% of cells within politically defined rural areas exhibited lower risk, more like those normally associated with "urban" locations. CONCLUSIONS In addition to increasing predictive power, the new continuous urbanicity metric provided a clearer mechanistic understanding than the dichotomous urban/rural designations. Such designations often ignore urban-like, low-risk pockets within traditionally rural areas, as were found in Malawi, along with rural-like, potentially high-risk environments within urban areas. This method of characterizing urbanicity can be applied to other infectious disease processes in rapidly urbanizing contexts.
Collapse
Affiliation(s)
- Peter S Larson
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Joseph N S Eisenberg
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Veronica J Berrocal
- Department of Statistics, School of Information and Computer Sciences, University of California, Irvine, CA, 92697, USA
| | - Don P Mathanga
- Malaria Alert Centre, College of Medicine, University of Malawi, Blantyre, Malawi
- Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Mark L Wilson
- Department of Epidemiology, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA.
| |
Collapse
|
11
|
Alves LD, Lana RM, Coelho FC. A Framework for Weather-Driven Dengue Virus Transmission Dynamics in Different Brazilian Regions. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18189493. [PMID: 34574418 PMCID: PMC8466780 DOI: 10.3390/ijerph18189493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 08/14/2021] [Accepted: 08/16/2021] [Indexed: 11/16/2022]
Abstract
This study investigated a model to assess the role of climate fluctuations on dengue (DENV) dynamics from 2010 to 2019 in four Brazilian municipalities. The proposed transmission model was based on a preexisting SEI-SIR model, but also incorporates the vector vertical transmission and the vector's egg compartment, thus allowing rainfall to be introduced to modulate egg-hatching. Temperature and rainfall satellite data throughout the decade were used as climatic model inputs. A sensitivity analysis was performed to understand the role of each parameter. The model-simulated scenario was compared to the observed dengue incidence and the findings indicate that the model was able to capture the observed seasonal dengue incidence pattern with good accuracy until 2016, although higher deviations were observed from 2016 to 2019. The results further demonstrate that vertical transmission fluctuations can affect attack transmission rates and patterns, suggesting the need to investigate the contribution of vertical transmission to dengue transmission dynamics in future assessments. The improved understanding of the relationship between different environment variables and dengue transmission achieved by the proposed model can contribute to public health policies regarding mosquito-borne diseases.
Collapse
Affiliation(s)
- Leon Diniz Alves
- Centro Federal Celso Suckow da Fonseca, Rio de Janeiro 20271-110, Brazil; or
- Computational Biology and Systems, Oswaldo Cruz Foundation, Rio de Janeiro 21040-900, Brazil
| | - Raquel Martins Lana
- Scientific Computing Program, Oswaldo Cruz Foundation, Rio de Janeiro 21040-900, Brazil; or
| | - Flávio Codeço Coelho
- School of Applied Mathematics, Getulio Vargas Foundation, Rio de Janeiro 22250-900, Brazil
- Institute of Global Health, University of Geneva, 1205 Geneva, Switzerland
- Correspondence: ; Tel.: +55-21-98725-1609
| |
Collapse
|
12
|
Okunlola OA, Oyeyemi OT, Lukman AF. Modeling the relationship between malaria prevalence and insecticide-treated bed net coverage in Nigeria using a Bayesian spatial generalized linear mixed model with a Leroux prior. Epidemiol Health 2021; 43:e2021041. [PMID: 34098626 PMCID: PMC8510838 DOI: 10.4178/epih.e2021041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/04/2021] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVES To evaluate malaria transmission in relation to insecticide-treated net (ITN) coverage in Nigeria. METHODS We used an exploratory analysis approach to evaluate variation in malaria transmission in relation to ITN distribution in 1,325 Demographic and Health Survey clusters in Nigeria. A Bayesian spatial generalized linear mixed model with a Leroux conditional autoregressive prior for the random effects was used to model the spatial and contextual variation in malaria prevalence and ITN distribution after adjusting for environmental variables. RESULTS Spatial smoothed maps showed the nationwide distribution of malaria and ITN. The distribution of ITN varied significantly across the 6 geopolitical zones (p<0.05). The North-East had the least ITN distribution (0.196±0.071), while ITN distribution was highest in the South-South (0.309±0.075). ITN coverage was also higher in rural areas (0.281±0.074) than in urban areas (0.240±0.096, p<0.05). The Bayesian hierarchical regression results showed a non-significant negative relationship between malaria prevalence and ITN coverage, but a significant spatial structured random effect and unstructured random effect. The correlates of malaria transmission included rainfall, maximum temperature, and proximity to water. CONCLUSIONS Reduction in malaria transmission was not significantly related to ITN coverage, although much could be achieved in attempts to curtail malaria transmission through enhanced ITN coverage. A multifaceted and integrated approach to malaria control is strongly advocated.
Collapse
Affiliation(s)
- Oluyemi A Okunlola
- Department of Mathematics, University of Medical Sciences, Ondo, Nigeria
| | - Oyetunde T Oyeyemi
- Department of Biological Sciences, University of Medical Sciences, Ondo, Nigeria
| | - Adewale F Lukman
- Department of Physical Sciences, Landmark University, Omu-Aran, Nigeria
| |
Collapse
|
13
|
Lee SA, Jarvis CI, Edmunds WJ, Economou T, Lowe R. Spatial connectivity in mosquito-borne disease models: a systematic review of methods and assumptions. J R Soc Interface 2021; 18:20210096. [PMID: 34034534 PMCID: PMC8150046 DOI: 10.1098/rsif.2021.0096] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/26/2021] [Indexed: 12/14/2022] Open
Abstract
Spatial connectivity plays an important role in mosquito-borne disease transmission. Connectivity can arise for many reasons, including shared environments, vector ecology and human movement. This systematic review synthesizes the spatial methods used to model mosquito-borne diseases, their spatial connectivity assumptions and the data used to inform spatial model components. We identified 248 papers eligible for inclusion. Most used statistical models (84.2%), although mechanistic are increasingly used. We identified 17 spatial models which used one of four methods (spatial covariates, local regression, random effects/fields and movement matrices). Over 80% of studies assumed that connectivity was distance-based despite this approach ignoring distant connections and potentially oversimplifying the process of transmission. Studies were more likely to assume connectivity was driven by human movement if the disease was transmitted by an Aedes mosquito. Connectivity arising from human movement was more commonly assumed in studies using a mechanistic model, likely influenced by a lack of statistical models able to account for these connections. Although models have been increasing in complexity, it is important to select the most appropriate, parsimonious model available based on the research question, disease transmission process, the spatial scale and availability of data, and the way spatial connectivity is assumed to occur.
Collapse
Affiliation(s)
- Sophie A. Lee
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Christopher I. Jarvis
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - W. John Edmunds
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | | | - Rachel Lowe
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| |
Collapse
|
14
|
Patterns and correlates of ownership and utilization of insecticide-treated bed-nets for malaria control among women of reproductive age (15-49 years) in Malawi. J Biosoc Sci 2021; 54:269-278. [PMID: 33526152 DOI: 10.1017/s002193202100002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Malaria is a major public health concern in Malawi. This study explored the patterns and correlates of ownership and utilization of ITNs for malaria control among women of reproductive age in Malawi. Data were derived from the multi-stage cross-sectional Malaria Indicator Survey (MIS) conducted in 2017, which followed ITN distribution in 2012 and 2015. Of the 3860 sampled women aged 15-49 years, 88% (3398/3860) and 64% (2473/3860) reported that they owned and utilized ITNs, respectively. Adjusted multivariate logistic regression analysis showed that the odds of ownership of ITNs were significantly low among women with no education (AOR = 0.36, CI = 0.18-0.72), those with primary education (AOR = 0.50, CI = 0.27-0.94) and poor women (AOR = 0.70, CI = 0.51-0.97). Similarly, the odds of utilization of ITNs were significantly low among women with no education, (AOR = 0.40, CI = 0.26-0.63), primary education (AOR = 0.53, CI = 0.36-0.78) and poor women (AOR = 0.70, CI = 0.51-0.97). Furthermore, the odds of utilization of ITNs were significantly low among women living in households without a radio (AOR = 0.79, CI = 0.67-0.93) and those who have not seen or heard a malaria message in the last 6 months (AOR = 0.74, CI = 0.64-0.87). In order to prevent malaria morbidity and mortality among women of reproductive age, especially those from poor households, the Malawi government and relevant stakeholders need to continue the free distribution of ITNs to the poor and encourage social behaviours that promote the ownership and utilization of ITNs.
Collapse
|
15
|
Topazian HM, Gumbo A, Puerto-Meredith S, Njiko R, Mwanza A, Kayange M, Mwalilino D, Mvula B, Tegha G, Mvalo T, Edwards JK, Emch M, Pettifor A, Smith JS, Hoffman I, Meshnick SR, Juliano JJ. Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015-2016. Sci Rep 2020; 10:18740. [PMID: 33127922 PMCID: PMC7603306 DOI: 10.1038/s41598-020-75261-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/13/2020] [Indexed: 11/25/2022] Open
Abstract
Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.
Collapse
Affiliation(s)
- Hillary M Topazian
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.
| | - Austin Gumbo
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | | | - Ruth Njiko
- University of North Carolina Project-Malawi, Lilongwe, Malawi
| | - Alexis Mwanza
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Michael Kayange
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | - David Mwalilino
- National HIV Reference Laboratory, Malawi Ministry of Health, Lilongwe, Malawi
| | - Bernard Mvula
- National HIV Reference Laboratory, Malawi Ministry of Health, Lilongwe, Malawi
| | - Gerald Tegha
- University of North Carolina Project-Malawi, Lilongwe, Malawi
| | - Tisungane Mvalo
- University of North Carolina Project-Malawi, Lilongwe, Malawi.,Department of Pediatrics, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Jessie K Edwards
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Michael Emch
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.,Department of Geography, University of North Carolina, Chapel Hill, NC, USA
| | - Audrey Pettifor
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.,Carolina Population Center, University of North Carolina, Chapel Hill, NC, USA
| | - Jennifer S Smith
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Irving Hoffman
- University of North Carolina Project-Malawi, Lilongwe, Malawi.,Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, USA
| | - Steven R Meshnick
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Jonathan J Juliano
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| |
Collapse
|
16
|
Yuan HY, Liang J, Lin PS, Sucipto K, Tsegaye MM, Wen TH, Pfeiffer S, Pfeiffer D. The effects of seasonal climate variability on dengue annual incidence in Hong Kong: A modelling study. Sci Rep 2020; 10:4297. [PMID: 32152334 PMCID: PMC7062697 DOI: 10.1038/s41598-020-60309-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 02/05/2020] [Indexed: 11/23/2022] Open
Abstract
In recent years, dengue has been rapidly spreading and growing in the tropics and subtropics. Located in southern China, Hong Kong’s subtropical monsoon climate may favour dengue vector populations and increase the chance of disease transmissions during the rainy summer season. An increase in local dengue incidence has been observed in Hong Kong ever since the first case in 2002, with an outbreak reaching historically high case numbers in 2018. However, the effects of seasonal climate variability on recent outbreaks are unknown. As the local cases were found to be spatially clustered, we developed a Poisson generalized linear mixed model using pre-summer monthly total rainfall and mean temperature to predict annual dengue incidence (the majority of local cases occur during or after the summer months), over the period 2002-2018 in three pre-defined areas of Hong Kong. Using leave-one-out cross-validation, 5 out of 6 observations of area-specific outbreaks during the major outbreak years 2002 and 2018 were able to be predicted. 42 out of a total of 51 observations (82.4%) were within the 95% confidence interval of the annual incidence predicted by our model. Our study found that the rainfall before and during the East Asian monsoon (pre-summer) rainy season is negatively correlated with the annual incidence in Hong Kong while the temperature is positively correlated. Hence, as mosquito control measures in Hong Kong are intensified mainly when heavy rainfalls occur during or close to summer, our study suggests that a lower-than-average intensity of pre-summer rainfall should also be taken into account as an indicator of increased dengue risk.
Collapse
Affiliation(s)
- Hsiang-Yu Yuan
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China.
| | - Jingbo Liang
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Pei-Sheng Lin
- Institute of Population Health Sciences, National Health Research Institutes, Miaoli County, Taiwan.,National Mosquito-borne Disease Control Research Center, National Health Research Institutes, Miaoli County, Taiwan
| | - Kathleen Sucipto
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Mesfin Mengesha Tsegaye
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Tzai-Hung Wen
- Department of Geography, National Taiwan University, Taipei City, Taiwan
| | - Susanne Pfeiffer
- Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Hong Kong, China
| | - Dirk Pfeiffer
- Centre for Applied One Health Research and Policy Advice, City University of Hong Kong, Hong Kong, China
| |
Collapse
|
17
|
Chirombo J, Ceccato P, Lowe R, Terlouw DJ, Thomson MC, Gumbo A, Diggle PJ, Read JM. Childhood malaria case incidence in Malawi between 2004 and 2017: spatio-temporal modelling of climate and non-climate factors. Malar J 2020; 19:5. [PMID: 31906963 PMCID: PMC6945411 DOI: 10.1186/s12936-019-3097-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/26/2019] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Malaria transmission is influenced by a complex interplay of factors including climate, socio-economic, environmental factors and interventions. Malaria control efforts across Africa have shown a mixed impact. Climate driven factors may play an increasing role with climate change. Efforts to strengthen routine facility-based monthly malaria data collection across Africa create an increasingly valuable data source to interpret burden trends and monitor control programme progress. A better understanding of the association with other climatic and non-climatic drivers of malaria incidence over time and space may help guide and interpret the impact of interventions. METHODS Routine monthly paediatric outpatient clinical malaria case data were compiled from 27 districts in Malawi between 2004 and 2017, and analysed in combination with data on climatic, environmental, socio-economic and interventional factors and district level population estimates. A spatio-temporal generalized linear mixed model was fitted using Bayesian inference, in order to quantify the strength of association of the various risk factors with district-level variation in clinical malaria rates in Malawi, and visualized using maps. RESULTS Between 2004 and 2017 reported childhood clinical malaria case rates showed a slight increase, from 50 to 53 cases per 1000 population, with considerable variation across the country between climatic zones. Climatic and environmental factors, including average monthly air temperature and rainfall anomalies, normalized difference vegetative index (NDVI) and RDT use for diagnosis showed a significant relationship with malaria incidence. Temperature in the current month and in each of the 3 months prior showed a significant relationship with the disease incidence unlike rainfall anomaly which was associated with malaria incidence at only three months prior. Estimated risk maps show relatively high risk along the lake and Shire valley regions of Malawi. CONCLUSION The modelling approach can identify locations likely to have unusually high or low risk of malaria incidence across Malawi, and distinguishes between contributions to risk that can be explained by measured risk-factors and unexplained residual spatial variation. Also, spatial statistical methods applied to readily available routine data provides an alternative information source that can supplement survey data in policy development and implementation to direct surveillance and intervention efforts.
Collapse
Affiliation(s)
- James Chirombo
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster University Medical School, Lancaster, UK
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Pietro Ceccato
- International Research Institute for Climate and Society, New York, USA
| | - Rachel Lowe
- Centre on Climate Change and Planetary Health & Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Barcelona Institute for Global Health, Barcelona, Spain
| | - Dianne J Terlouw
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Austin Gumbo
- National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | - Peter J Diggle
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster University Medical School, Lancaster, UK
| | - Jonathan M Read
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster University Medical School, Lancaster, UK
| |
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
Matsushita N, Kim Y, Ng CFS, Moriyama M, Igarashi T, Yamamoto K, Otieno W, Minakawa N, Hashizume M. Differences of Rainfall-Malaria Associations in Lowland and Highland in Western Kenya. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:ijerph16193693. [PMID: 31575076 PMCID: PMC6801446 DOI: 10.3390/ijerph16193693] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 09/24/2019] [Accepted: 09/26/2019] [Indexed: 01/05/2023]
Abstract
Many studies have reported a relationship between climate factors and malaria. However, results were inconsistent across the areas. We examined associations between climate factors and malaria in two geographically different areas: lowland (lakeside area) and highland in Western Kenya. Associations between climate factors (rainfall, land surface temperature (LST), and lake water level (LWL)) and monthly malaria cases from 2000 to 2013 in six hospitals (two in lowland and four in highland) were analyzed using time-series regression analysis with a distributed lag nonlinear model (DLNM) and multivariate meta-analysis. We found positive rainfall–malaria overall associations in lowland with a peak at 120 mm of monthly rainfall with a relative risk (RR) of 7.32 (95% CI: 2.74, 19.56) (reference 0 mm), whereas similar associations were not found in highland. Positive associations were observed at lags of 2 to 4 months at rainfall around 100–200 mm in both lowland and highland. The RRs at 150 mm rainfall were 1.42 (95% CI: 1.18, 1.71) in lowland and 1.20 (95% CI: 1.07, 1.33) in highland (at a lag of 3 months). LST and LWL did not show significant association with malaria. The results suggest that geographical characteristics can influence climate–malaria relationships.
Collapse
Affiliation(s)
- Naohiko Matsushita
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine (NEKKEN), Nagasaki University. Nagasaki 852-8523, Japan.
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8523, Japan.
| | - Yoonhee Kim
- Department of Global Environmental Health, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Chris Fook Sheng Ng
- School of Tropical Medicine and Global Health (TMGH), Nagasaki University, Nagasaki 852-8523, Japan.
| | - Masao Moriyama
- Division of Electrical Engineering and Computer Science, Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan.
| | - Tamotsu Igarashi
- Remote Sensing Technology Center of Japan (RESTEC), Tokyo 105-0001, Japan.
| | | | - Wellington Otieno
- Centre for Research and Technology Development Maseno University, Kisumu 40100, Kenya.
| | - Noboru Minakawa
- Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
| | - Masahiro Hashizume
- Department of Paediatric Infectious Diseases, Institute of Tropical Medicine (NEKKEN), Nagasaki University. Nagasaki 852-8523, Japan.
- School of Tropical Medicine and Global Health (TMGH), Nagasaki University, Nagasaki 852-8523, Japan.
| |
Collapse
|
20
|
Davis JK, Gebrehiwot T, Worku M, Awoke W, Mihretie A, Nekorchuk D, Wimberly MC. A genetic algorithm for identifying spatially-varying environmental drivers in a malaria time series model. ENVIRONMENTAL MODELLING & SOFTWARE : WITH ENVIRONMENT DATA NEWS 2019; 119:275-284. [PMID: 33814961 PMCID: PMC8018598 DOI: 10.1016/j.envsoft.2019.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Time series models of malaria cases can be applied to forecast epidemics and support proactive interventions. Mosquito life history and parasite development are sensitive to environmental factors such as temperature and precipitation, and these variables are often used as predictors in malaria models. However, malaria-environment relationships can vary with ecological and social context. We used a genetic algorithm to optimize a spatiotemporal malaria model by aggregating locations into clusters with similar environmental sensitivities. We tested the algorithm in the Amhara Region of Ethiopia using seven years of weekly Plasmodium falciparum data from 47 districts and remotely-sensed land surface temperature, precipitation, and spectral indices as predictors. The best model identified six clusters, and the districts in each cluster had distinctive responses to the environmental predictors. We conclude that spatial stratification can improve the fit of environmentally-driven disease models, and genetic algorithms provide a practical and effective approach for identifying these clusters.
Collapse
Affiliation(s)
- Justin K. Davis
- Dept. of Geography and Environmental Sustainability, University of Oklahoma, Norman OK, United States
| | | | | | - Worku Awoke
- School of Public Health, Bahir Dar University, Bahir Dar, Ethiopia
| | - Abere Mihretie
- Health, Development, and Anti-Malaria Association, Addis Ababa, Ethiopia
| | - Dawn Nekorchuk
- Dept. of Geography and Environmental Sustainability, University of Oklahoma, Norman OK, United States
| | - Michael C. Wimberly
- Dept. of Geography and Environmental Sustainability, University of Oklahoma, Norman OK, United States
| |
Collapse
|
21
|
Ouédraogo M, Samadoulougou S, Rouamba T, Hien H, Sawadogo JEM, Tinto H, Alegana VA, Speybroeck N, Kirakoya-Samadoulougou F. Spatial distribution and determinants of asymptomatic malaria risk among children under 5 years in 24 districts in Burkina Faso. Malar J 2018; 17:460. [PMID: 30526598 PMCID: PMC6286519 DOI: 10.1186/s12936-018-2606-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 12/01/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND In malaria endemic countries, asymptomatic cases constitute an important reservoir of infections sustaining transmission. Estimating the burden of the asymptomatic population and identifying areas with elevated risk is important for malaria control in Burkina Faso. This study analysed the spatial distribution of asymptomatic malaria infection among children under 5 in 24 health districts in Burkina Faso and identified the determinants of this distribution. METHODS The data used in this study were collected in a baseline survey on "evaluation of the impact of pay for performance on the quality of care" conducted in 24 health districts in Burkina Faso, between October 2013 and March 2014. This survey involved 7844 households and 1387 community health workers. A Bayesian hierarchical logistic model that included spatial dependence and covariates was implemented to identify the determinants of asymptomatic malaria infection. The posterior probability distribution of a parameter from the model was summarized using odds ratio (OR) and 95% credible interval (95% CI). RESULTS The overall prevalence of asymptomatic malaria infection in children under 5 years of age was estimated at 38.2%. However, significant variation was observed between districts ranging from 11.1% in the district of Barsalgho to 77.8% in the district of Gaoua. Older children (48-59 vs < 6 months: OR: 6.79 [5.62, 8.22]), children from very poor households (Richest vs poorest: OR: 0.85 [0.74-0.96]), households located more than 5 km from a health facility (< 5 km vs ≥ 5 km: OR: 1.14 [1.04-1.25]), in localities with inadequate number of nurses (< 3 vs ≥ 3: 0.72 [0.62, 0.82], from rural areas (OR: 1.67 [1.39-2.01]) and those surveyed in high transmission period of asymptomatic malaria (OR: 1.27 [1.10-1.46]) were most at risk for asymptomatic malaria infection. In addition, the spatial analysis identified the following nine districts that reported significantly higher risks: Batié, Boromo, Dano, Diébougou, Gaoua, Ouahigouya, Ouargaye, Sapouy and Toma. The district of Zabré reported the lowest risk. CONCLUSION The analysis of spatial distribution of infectious reservoir allowed the identification of risk areas as well as the identification of individual and contextual factors. Such national spatial analysis should help to prioritize areas for increased malaria control activities.
Collapse
Affiliation(s)
- Mady Ouédraogo
- Centre de Recherche en Epidémiologie, Biostatistiques et Recherche Clinique, Ecole de Santé Publique, Université libre de Bruxelles, Brussels, Belgium.,Institut de Recherche Santé et Sociétés, Faculté de Santé Publique, Université catholique de Louvain, Brussels, Belgium
| | - Sékou Samadoulougou
- Pôle Epidémiologie et Biostatistique, Institut de Recherche Expérimentale et Clinique, Faculté de Santé Publique, Université catholique de Louvain, Brussels, Belgium
| | - Toussaint Rouamba
- Centre de Recherche en Epidémiologie, Biostatistiques et Recherche Clinique, Ecole de Santé Publique, Université libre de Bruxelles, Brussels, Belgium.,Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Centre National de la Recherche Scientifique et Technologique, Ouagadougou, Burkina Faso
| | - Hervé Hien
- Département de Santé Publique, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - John E M Sawadogo
- Département de Santé Publique, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Centre National de la Recherche Scientifique et Technologique, Ouagadougou, Burkina Faso
| | - Victor A Alegana
- Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Niko Speybroeck
- Institut de Recherche Santé et Sociétés, Faculté de Santé Publique, Université catholique de Louvain, Brussels, Belgium
| | - Fati Kirakoya-Samadoulougou
- Centre de Recherche en Epidémiologie, Biostatistiques et Recherche Clinique, Ecole de Santé Publique, Université libre de Bruxelles, Brussels, Belgium.
| |
Collapse
|
22
|
Ugwu CLJ, Zewotir TT. Using mixed effects logistic regression models for complex survey data on malaria rapid diagnostic test results. Malar J 2018; 17:453. [PMID: 30518399 PMCID: PMC6282337 DOI: 10.1186/s12936-018-2604-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/29/2018] [Indexed: 11/10/2022] Open
Abstract
Background The effect of malaria in Nigeria is still worrisome and has remained a leading public health issue in the country. In 2016, Nigeria was the highest malaria burden country among the 15 countries in sub-Saharan Africa that accounted for the 80% global malaria cases. The purpose of this study is to utilize appropriate statistical models in identifying socio-economic, demographic and geographic risk factors that have influenced malaria transmission in Nigeria, based on malaria rapid diagnostic test survey results. This study contributes towards re-designing intervention strategies to achieve the target of meeting the Sustainable Development Goals 2030 Agenda for total malaria elimination. Methods This study adopted the generalized linear mixed models approach which accounts for the complexity of the sample survey design associated with the data. The 2015 Nigeria malaria indicator survey data of children between 6 and 59 months are used in the study. Results From the findings of this study, the cluster effect is significant \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$(P<0.0001)$$\end{document}(P<0.0001) which has suggested evidence of heterogeneity among the clusters. It was found that the vulnerability of a child to malaria infection increases as the child advances in age. Other major significant factors were; the presence of anaemia in a child, an area where a child resides (urban or rural), the level of the mother’s education, poverty level, number of household members, sanitation, age of head of household, availability of electricity and the type of material for roofing. Moreover, children from Northern and South-West regions were also found to be at higher risk of malaria disease and re-infection. Conclusion Improvement of socio-economic development and quality of life is paramount to achieving malaria free Nigeria. There is a strong link of malaria risk with poverty, under-development and the mother’s educational level.
Collapse
Affiliation(s)
- Chigozie Louisa J Ugwu
- School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Westville Campus, Durban, South Africa.
| | - Temesgen T Zewotir
- School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Westville Campus, Durban, South Africa
| |
Collapse
|
23
|
Tompkins AM, Thomson MC. Uncertainty in malaria simulations in the highlands of Kenya: Relative contributions of model parameter setting, driving climate and initial condition errors. PLoS One 2018; 13:e0200638. [PMID: 30256799 PMCID: PMC6157844 DOI: 10.1371/journal.pone.0200638] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 06/29/2018] [Indexed: 11/23/2022] Open
Abstract
In this study, experiments are conducted to gauge the relative importance of model, initial condition, and driving climate uncertainty for simulations of malaria transmission at a highland plantation in Kericho, Kenya. A genetic algorithm calibrates each of these three factors within their assessed prior uncertainty in turn to see which allows the best fit to a timeseries of confirmed cases. It is shown that for high altitude locations close to the threshold for transmission, the spatial representativeness uncertainty for climate, in particular temperature, dominates the uncertainty due to model parameter settings. Initial condition uncertainty plays little role after the first two years, and is thus important in the early warning system context, but negligible for decadal and climate change investigations. Thus, while reducing uncertainty in the model parameters would improve the quality of the simulations, the uncertainty in the temperature driving data is critical. It is emphasized that this result is a function of the mean climate of the location itself, and it is shown that model uncertainty would be relatively more important at warmer, lower altitude locations.
Collapse
Affiliation(s)
- Adrian M. Tompkins
- Earth System Physics, The Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy
- * E-mail:
| | - Madeleine C. Thomson
- International Research Institute for Climate and Society, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, United States of America
| |
Collapse
|
24
|
Hasyim H, Dhimal M, Bauer J, Montag D, Groneberg DA, Kuch U, Müller R. Does livestock protect from malaria or facilitate malaria prevalence? A cross-sectional study in endemic rural areas of Indonesia. Malar J 2018; 17:302. [PMID: 30126462 PMCID: PMC6102806 DOI: 10.1186/s12936-018-2447-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/05/2018] [Indexed: 11/20/2022] Open
Abstract
Background Ever since it was discovered that zoophilic vectors can transmit malaria, zooprophylaxis has been used to prevent the disease. However, zoopotentiation has also been observed. Thus, the presence of livestock has been widely accepted as an important variable for the prevalence and risk of malaria, but the effectiveness of zooprophylaxis remained subject to debate. This study aims to critically analyse the effects of the presence of livestock on malaria prevalence using a large dataset from Indonesia. Methods This study is based on data from the Indonesia Basic Health Research (“Riskesdas”) cross-sectional survey of 2007 organized by the National Institute of Health Research and Development of Indonesia’s Ministry of Health. The subset of data used in the present study included 259,885 research participants who reside in the rural areas of 176 regencies throughout the 15 provinces of Indonesia where the prevalence of malaria is higher than the national average. The variable “existence of livestock” and other independent demographic, social and behavioural variables were tested as potential determinants for malaria prevalence by multivariate logistic regressions. Results Raising medium-sized animals in the house was a significant predictor of malaria prevalence (OR = 2.980; 95% CI 2.348–3.782, P < 0.001) when compared to keeping such animals outside of the house (OR = 1.713; 95% CI 1.515–1.937, P < 0.001). After adjusting for gender, age, access to community health facility, sewage canal condition, use of mosquito nets and insecticide-treated bed nets, the participants who raised medium-sized animals inside their homes were 2.8 times more likely to contract malaria than respondents who did not (adjusted odds ratio = 2.809; 95% CI 2.207–3.575; P < 0.001). Conclusions The results of this study highlight the importance of livestock for malaria transmission, suggesting that keeping livestock in the house contributes to malaria risk rather than prophylaxis in Indonesia. Livestock-based interventions should therefore play a significant role in the implementation of malaria control programmes, and focus on households with a high proportion of medium-sized animals in rural areas. The implementation of a “One Health” strategy to eliminate malaria in Indonesia by 2030 is strongly recommended. Electronic supplementary material The online version of this article (10.1186/s12936-018-2447-6) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Hamzah Hasyim
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany. .,Faculty of Public Health, Sriwijaya University, Indralaya, South Sumatra, Indonesia.
| | - Meghnath Dhimal
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Nepal Health Research Council, Ramshah Path, Kathmandu, Nepal
| | - Jan Bauer
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Doreen Montag
- Centre for Primary Care and Public Health, Barts and the London School of Medicine, Queen Mary University of London, London, UK
| | - David A Groneberg
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Ulrich Kuch
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Ruth Müller
- Faculty of Medicine, Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| |
Collapse
|
25
|
M’Bra RK, Kone B, Soro DP, N’krumah RTAS, Soro N, Ndione JA, Sy I, Ceccato P, Ebi KL, Utzinger J, Schindler C, Cissé G. Impact of climate variability on the transmission risk of malaria in northern Côte d'Ivoire. PLoS One 2018; 13:e0182304. [PMID: 29897901 PMCID: PMC5999085 DOI: 10.1371/journal.pone.0182304] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/16/2018] [Indexed: 11/19/2022] Open
Abstract
Since the 1970s, the northern part of Côte d'Ivoire has experienced considerable fluctuation in its meteorology including a general decrease of rainfall and increase of temperature from 1970 to 2000, a slight increase of rainfall since 2000, a severe drought in 2004-2005 and flooding in 2006-2007. Such changing climate patterns might affect the transmission of malaria. The purpose of this study was to analyze climate and environmental parameters associated with malaria transmission in Korhogo, a city in northern Côte d'Ivoire. All data were collected over a 10-year period (2004-2013). Rainfall, temperature and Normalized Difference Vegetation Index (NDVI) were the climate and environmental variables considered. Association between these variables and clinical malaria data was determined, using negative binomial regression models. From 2004 to 2013, there was an increase in the annual average precipitation (1100.3-1376.5 mm) and the average temperature (27.2°C-27.5°C). The NDVI decreased from 0.42 to 0.40. We observed a strong seasonality in these climatic variables, which resembled the seasonality in clinical malaria. An incremental increase of 10 mm of monthly precipitation was, on average, associated with a 1% (95% Confidence interval (CI): 0.7 to 1.2%) and a 1.2% (95% CI: 0.9 to 1.5%) increase in the number of clinical malaria episodes one and two months later respectively. A 1°C increase in average monthly temperature was, on average, associated with a decline of a 3.5% (95% CI: 0.1 to 6.7%) in clinical malaria episodes. A 0.1 unit increase in monthly NDVI was associated with a 7.3% (95% CI: 0.8 to 14.1%) increase in the monthly malaria count. There was a similar increase for the preceding-month lag (6.7% (95% CI: 2.3% to 11.2%)). The study results can be used to establish a malaria early warning system in Korhogo to prepare for outbreaks of malaria, which would increase community resilience no matter the magnitude and pattern of climate change.
Collapse
Affiliation(s)
- Richard K. M’Bra
- Unité de Formation et de Recherche Sciences de la Terre et des Ressources Minières, Université Félix Houphouët Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail: ,
| | - Brama Kone
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Institut de Gestion Agropastorale, Université Péléforo Gon Coulibaly, Korhogo, Côte d’Ivoire
| | - Dramane P. Soro
- Unité de Formation et de Recherche Sciences de la Terre et des Ressources Minières, Université Félix Houphouët Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
| | - Raymond T. A. S. N’krumah
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Unité de Formation et de Recherche des Sciences Médicales, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
| | - Nagnin Soro
- Unité de Formation et de Recherche Sciences de la Terre et des Ressources Minières, Université Félix Houphouët Boigny, Abidjan, Côte d’Ivoire
| | | | | | - Pietro Ceccato
- International Research Institute for Climate and Society, Columbia University, New York, New York, United States of America
| | - Kristie L. Ebi
- Department of Global Health School of Public Health University of Washington, Seattle, Washington, United States of America
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christian Schindler
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Guéladio Cissé
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| |
Collapse
|
26
|
Verma P, Sarkar S, Singh P, Dhiman RC. Devising a method towards development of early warning tool for detection of malaria outbreak. Indian J Med Res 2018; 146:612-621. [PMID: 29512603 PMCID: PMC5861472 DOI: 10.4103/ijmr.ijmr_426_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background & objectives Uncertainty often arises in differentiating seasonal variation from outbreaks of malaria. The present study was aimed to generalize the theoretical structure of sine curve for detecting an outbreak so that a tool for early warning of malaria may be developed. Methods A 'case/mean-ratio scale' system was devised for labelling the outbreak in respect of two diverse districts of Assam and Rajasthan. A curve-based method of analysis was developed for determining outbreak and using the properties of sine curve. It could be used as an early warning tool for Plasmodium falciparum malaria outbreaks. Result In the present method of analysis, the critical Cmax(peak value of sine curve) value of seasonally adjusted curve for P. falciparum malaria outbreak was 2.3 for Karbi Anglong and 2.2 for Jaisalmer districts. On case/mean-ratio scale, the Cmax value of malaria curve between Cmaxand 3.5, the outbreak could be labelled as minor while >3.5 may be labelled as major. In epidemic years, with mean of case/mean ratio of ≥1.00 and root mean square (RMS) ≥1.504 of case/mean ratio, outbreaks can be predicted 1-2 months in advance. Interpretation & conclusions The present study showed that in P. falciparum cases in Karbi Anglong (Assam) and Jaisalmer (Rajasthan) districts, the rise in Cmaxvalue of curve was always followed by rise in average/RMS or both and hence could be used as an early warning tool. The present method provides better detection of outbreaks than the conventional method of mean plus two standard deviation (mean+2 SD). The identified tools are simple and may be adopted for preparedness of malaria outbreaks.
Collapse
Affiliation(s)
- Preeti Verma
- Environmental Epidemiology Division, ICMR-National Institute of Malaria Research, New Delhi, India
| | - Soma Sarkar
- Environmental Epidemiology Division, ICMR-National Institute of Malaria Research, New Delhi, India
| | - Poonam Singh
- Environmental Epidemiology Division, ICMR-National Institute of Malaria Research, New Delhi, India
| | - Ramesh C Dhiman
- Environmental Epidemiology Division, ICMR-National Institute of Malaria Research, New Delhi, India
| |
Collapse
|
27
|
Sadoine ML, Smargiassi A, Ridde V, Tusting LS, Zinszer K. The associations between malaria, interventions, and the environment: a systematic review and meta-analysis. Malar J 2018; 17:73. [PMID: 29415721 PMCID: PMC5803989 DOI: 10.1186/s12936-018-2220-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/31/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Malaria transmission is driven by multiple factors, including complex and multifaceted connections between malaria transmission, socioeconomic conditions, climate and interventions. Forecasting models should account for all significant drivers of malaria incidence although it is first necessary to understand the relationship between malaria burden and the various determinants of risk to inform the development of forecasting models. In this study, the associations between malaria risk, environmental factors, and interventions were evaluated through a systematic review. METHODS Five electronic databases (CAB Abstracts, EMBASE, Global Health, MEDLINE and ProQuest Dissertations & Theses) were searched for studies that included both the effects of the environment and interventions on malaria within the same statistical model. Studies were restricted to quantitative analyses and health outcomes of malaria mortality or morbidity, outbreaks, or transmission suitability. Meta-analyses were conducted on a subset of results using random-effects models. RESULTS Eleven studies of 2248 potentially relevant articles that met inclusion criteria were identified for the systematic review and two meta-analyses based upon five results each were performed. Normalized Difference Vegetation Index was not found to be statistically significant associated with malaria with a pooled OR of 1.10 (95% CI 0.07, 1.71). Bed net ownership was statistically associated with decreasing risk of malaria, when controlling for the effects of environment with a pooled OR of 0.75 (95% CI 0.60, 0.95). In general, environmental effects on malaria, while controlling for the effect of interventions, were variable and showed no particular pattern. Bed nets ownership, use and distribution, have a significant protective effect while controlling for environmental variables. CONCLUSIONS There are a limited number of studies which have simultaneously evaluated both environmental and interventional effects on malaria risk. Poor statistical reporting and a lack of common metrics were important challenges for this review, which must be addressed to ensure reproducibility and quality research. A comprehensive or inclusive approach to identifying malaria determinants using standardized indicators would allow for a better understanding of its epidemiology, which is crucial to improve future malaria risk estimations.
Collapse
Affiliation(s)
- Margaux L Sadoine
- Université de Montréal Public Health Research Institute (Institut de Recherche en Santé Publique (IRSPUM)), Université de Montréal, Montréal, QC, Canada.
- School of Public Health, Department of Social and Preventive Medicine, Université de Montréal, Montréal, QC, Canada.
| | - Audrey Smargiassi
- Université de Montréal Public Health Research Institute (Institut de Recherche en Santé Publique (IRSPUM)), Université de Montréal, Montréal, QC, Canada
- School of Public Health, Department of Environmental and Occupational Health, Université de Montréal, Montréal, QC, Canada
- Institut national de santé publique du Québec, Montréal, QC, Canada
| | - Valéry Ridde
- Université de Montréal Public Health Research Institute (Institut de Recherche en Santé Publique (IRSPUM)), Université de Montréal, Montréal, QC, Canada
- School of Public Health, Department of Social and Preventive Medicine, Université de Montréal, Montréal, QC, Canada
| | - Lucy S Tusting
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Kate Zinszer
- Université de Montréal Public Health Research Institute (Institut de Recherche en Santé Publique (IRSPUM)), Université de Montréal, Montréal, QC, Canada
- School of Public Health, Department of Social and Preventive Medicine, Université de Montréal, Montréal, QC, Canada
| |
Collapse
|
28
|
Smith J, Tahani L, Bobogare A, Bugoro H, Otto F, Fafale G, Hiriasa D, Kazazic A, Beard G, Amjadali A, Jeanne I. Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands. Malar J 2017; 16:472. [PMID: 29162098 PMCID: PMC5697090 DOI: 10.1186/s12936-017-2120-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 11/14/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria control remains a significant challenge in the Solomon Islands. Despite progress made by local malaria control agencies over the past decade, case rates remain high in some areas of the country. Studies from around the world have confirmed important links between climate and malaria transmission. This study focuses on understanding the links between malaria and climate in Guadalcanal, Solomon Islands, with a view towards developing a climate-based monitoring and early warning for periods of enhanced malaria transmission. METHODS Climate records were sourced from the Solomon Islands meteorological service (SIMS) and historical malaria case records were sourced from the National Vector-Borne Disease Control Programme (NVBDCP). A declining trend in malaria cases over the last decade associated with improved malaria control was adjusted for. A stepwise regression was performed between climate variables and climate-associated malaria transmission (CMT) at different lag intervals to determine where significant relationships existed. The suitability of these results for use in a three-tiered categorical warning system was then assessed using a Mann-Whitney U test. RESULTS Of the climate variables considered, only rainfall had a consistently significant relationship with malaria in North Guadalcanal. Optimal lag intervals were determined for prediction using R2 skill scores. A highly significant negative correlation (R = - 0.86, R2 = 0.74, p < 0.05, n = 14) was found between October and December rainfall at Honiara and CMT in northern Guadalcanal for the subsequent January-June. This indicates that drier October-December periods are followed by higher malaria transmission periods in January-June. Cross-validation emphasized the suitability of this relationship for forecasting purposes [Formula: see text] as did Mann-Whitney U test results showing that rainfall below or above specific thresholds was significantly associated with above or below normal malaria transmission, respectively. CONCLUSION This study demonstrated that rainfall provides the best predictor of malaria transmission in North Guadalcanal. This relationship is thought to be underpinned by the unique hydrological conditions in northern Guadalcanal which allow sandbars to form across the mouths of estuaries which act to develop or increase stagnant brackish marshes in low rainfall periods. These are ideal habitats for the main mosquito vector, Anopheles farauti. High rainfall accumulations result in the flushing of these habitats, reducing their viability. The results of this study are now being used as the basis of a malaria early warning system which has been jointly implemented by the SIMS, NVBDCP and the Australian Bureau of Meteorology.
Collapse
Affiliation(s)
- Jason Smith
- Australian Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC, 3008, Australia
| | - Lloyd Tahani
- Solomon Islands Meteorological Service, Honiara, Capital Territory, Solomon Islands
| | - Albino Bobogare
- National Vector Borne Disease Control Programme, Honiara, Capital Territory, Solomon Islands
| | - Hugo Bugoro
- National Vector Borne Disease Control Programme, Honiara, Capital Territory, Solomon Islands
| | - Francis Otto
- National Vector Borne Disease Control Programme, Honiara, Capital Territory, Solomon Islands
| | - George Fafale
- National Vector Borne Disease Control Programme, Honiara, Capital Territory, Solomon Islands
| | - David Hiriasa
- Solomon Islands Meteorological Service, Honiara, Capital Territory, Solomon Islands
| | - Adna Kazazic
- Australian Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC, 3008, Australia
| | - Grant Beard
- Australian Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC, 3008, Australia
| | - Amanda Amjadali
- Australian Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC, 3008, Australia.,Pacific Science Solutions, Suva, Fiji
| | - Isabelle Jeanne
- Australian Bureau of Meteorology, 700 Collins St, Docklands, Melbourne, VIC, 3008, Australia.
| |
Collapse
|
29
|
Reprint of "Modelling the influence of temperature and rainfall on malaria incidence in four endemic provinces of Zambia using semiparametric Poisson regression". Acta Trop 2017; 175:60-70. [PMID: 28867394 DOI: 10.1016/j.actatropica.2017.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Although malaria morbidity and mortality are greatly reduced globally owing to great control efforts, the disease remains the main contributor. In Zambia, all provinces are malaria endemic. However, the transmission intensities vary mainly depending on environmental factors as they interact with the vectors. Generally in Africa, possibly due to the varying perspectives and methods used, there is variation on the relative importance of malaria risk determinants. In Zambia, the role climatic factors play on malaria case rates has not been determined in combination of space and time using robust methods in modelling. This is critical considering the reversal in malaria reduction after the year 2010 and the variation by transmission zones. Using a geoadditive or structured additive semiparametric Poisson regression model, we determined the influence of climatic factors on malaria incidence in four endemic provinces of Zambia. We demonstrate a strong positive association between malaria incidence and precipitation as well as minimum temperature. The risk of malaria was 95% lower in Lusaka (ARR=0.05, 95% CI=0.04-0.06) and 68% lower in the Western Province (ARR=0.31, 95% CI=0.25-0.41) compared to Luapula Province. North-western Province did not vary from Luapula Province. The effects of geographical region are clearly demonstrated by the unique behaviour and effects of minimum and maximum temperatures in the four provinces. Environmental factors such as landscape in urbanised places may also be playing a role.
Collapse
|
30
|
Thomson MC, Ukawuba I, Hershey CL, Bennett A, Ceccato P, Lyon B, Dinku T. Using Rainfall and Temperature Data in the Evaluation of National Malaria Control Programs in Africa. Am J Trop Med Hyg 2017; 97:32-45. [PMID: 28990912 PMCID: PMC5619931 DOI: 10.4269/ajtmh.16-0696] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/29/2016] [Indexed: 11/17/2022] Open
Abstract
Since 2010, the Roll Back Malaria (RBM) Partnership, including National Malaria Control Programs, donor agencies (e.g., President's Malaria Initiative and Global Fund), and other stakeholders have been evaluating the impact of scaling up malaria control interventions on all-cause under-five mortality in several countries in sub-Saharan Africa. The evaluation framework assesses whether the deployed interventions have had an impact on malaria morbidity and mortality and requires consideration of potential nonintervention influencers of transmission, such as drought/floods or higher temperatures. Herein, we assess the likely effect of climate on the assessment of the impact malaria interventions in 10 priority countries/regions in eastern, western, and southern Africa for the President's Malaria Initiative. We used newly available quality controlled Enhanced National Climate Services rainfall and temperature products as well as global climate products to investigate likely impacts of climate on malaria evaluations and test the assumption that changing the baseline period can significantly impact on the influence of climate in the assessment of interventions. Based on current baseline periods used in national malaria impact assessments, we identify three countries/regions where current evaluations may overestimate the impact of interventions (Tanzania, Zanzibar, Uganda) and three countries where current malaria evaluations may underestimate the impact of interventions (Mali, Senegal and Ethiopia). In four countries (Rwanda, Malawi, Mozambique, and Angola) there was no strong difference in climate suitability for malaria in the pre- and post-intervention period. In part, this may be due to data quality and analysis issues.
Collapse
Affiliation(s)
- Madeleine C. Thomson
- International Research Institute for Climate and Society, Palisades, New York
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York
| | - Israel Ukawuba
- International Research Institute for Climate and Society, Palisades, New York
| | - Christine L. Hershey
- President's Malaria Initiative, United States Agency for International Development, Washington, District of Columbia
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California
| | - Pietro Ceccato
- International Research Institute for Climate and Society, Palisades, New York
| | - Bradfield Lyon
- International Research Institute for Climate and Society, Palisades, New York
| | - Tufa Dinku
- International Research Institute for Climate and Society, Palisades, New York
| |
Collapse
|
31
|
Hajison PL, Mwakikunga BW, Mathanga DP, Feresu SA. Seasonal variation of malaria cases in children aged less than 5 years old following weather change in Zomba district, Malawi. Malar J 2017; 16:264. [PMID: 28673290 PMCID: PMC5496322 DOI: 10.1186/s12936-017-1913-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 06/26/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is seasonal and this may influence the number of children being treated as outpatients in hospitals. The objective of this study was to investigate the degree of seasonality in malaria in lakeshore and highland areas of Zomba district Malawi, and influence of climatic factors on incidence of malaria. METHODS Secondary data on malaria surveillance numbers and dates of treatment of children <5 years of age (n = 374,246) were extracted from the Zomba health information system for the period 2012-2016, while data on climatic variables from 2012 to 2015 were obtained from meteorological department. STATA version 13 was used to analyse data using non-linear time series correlation test to suggest a predictor model of malaria epidemic over explanatory variable (rainfall, temperature and humidity). RESULTS Malaria cases of children <5 years of age in Zomba district accounts for 45% of general morbidity. There was no difference in seasonality of malaria in highland compared to lakeshore in Zomba district. This study also found that an increase in average temperature and relative humidity was associated of malaria incidence in children <5 year of age in Zomba district. On the other hand, the difference of maximum and minimum temperature (diurnal temperature range), had a strong negative association (correlation coefficients of R2 = 0.563 [All Zomba] β = -1295.57 95% CI -1683.38 to -907.75 p value <0.001, R2 = 0.395 [Zomba Highlands] β = -137.74 95% CI -195.00 to -80.47 p value <0.001 and R2 = 0.470 [Zomba Lakeshores] β = -263.05 95% CI -357.47 to -168.63 p value <0.001) with malaria incidence of children <5 year in Zomba district, Malawi. CONCLUSION The diminishing of malaria seasonality, regardless of strong rainfall seasonality, and marginal drop of malaria incidence in Zomba can be explained by weather variation. Implementation of seasonal chemoprevention of malaria in Zomba could be questionable due to reduced seasonality of malaria. The lower diurnal temperature range contributed to high malaria incidence and this must be further investigated.
Collapse
Affiliation(s)
- Precious L Hajison
- Invest in Knowledge, Epidemiology Research Unit, Zomba, Malawi. .,School of Health Systems and Public Health, Epidemiology & Biostatistics Track, University of Pretoria, 5-10 H.W. Snyman Building, Pretoria, South Africa.
| | - Bonex W Mwakikunga
- DST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, South Africa.
| | - Don P Mathanga
- Malaria Alert Centre & Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Shingairai A Feresu
- School of Health Systems and Public Health, Epidemiology & Biostatistics Track, University of Pretoria, 5-10 H.W. Snyman Building, Pretoria, South Africa
| |
Collapse
|
32
|
Gómez-Barroso D, García-Carrasco E, Herrador Z, Ncogo P, Romay-Barja M, Ondo Mangue ME, Nseng G, Riloha M, Santana MA, Valladares B, Aparicio P, Benito A. Spatial clustering and risk factors of malaria infections in Bata district, Equatorial Guinea. Malar J 2017; 16:146. [PMID: 28403879 PMCID: PMC5389164 DOI: 10.1186/s12936-017-1794-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/31/2017] [Indexed: 11/22/2022] Open
Abstract
Background The transmission of malaria is intense in the majority of the countries of sub-Saharan Africa, particularly in those that are located along the Equatorial strip. The present study aimed to describe the current distribution of malaria prevalence among children and its environment-related factors as well as to detect malaria spatial clusters in the district of Bata, in Equatorial Guinea. Methods From June to August 2013 a representative cross-sectional survey using a multistage, stratified, cluster-selected sample was carried out of children in urban and rural areas of Bata District. All children were tested for malaria using rapid diagnostic tests (RDTs). Results were linked to each household by global position system data. Two cluster analysis methods were used: hot spot analysis using the Getis-Ord Gi statistic, and the SaTScan™ spatial statistic estimates, based on the assumption of a Poisson distribution to detect spatial clusters. In addition, univariate associations and Poisson regression model were used to explore the association between malaria prevalence at household level with different environmental factors. Results A total of 1416 children aged 2 months to 15 years living in 417 households were included in this study. Malaria prevalence by RDTs was 47.53%, being highest in the age group 6–15 years (63.24%, p < 0.001). Those children living in rural areas were there malaria risk is greater (65.81%) (p < 0.001). Malaria prevalence was higher in those houses located <1 km from a river and <3 km to a forest (IRR: 1.31; 95% CI 1.13–1.51 and IRR: 1.44; 95% CI 1.25–1.66, respectively). Poisson regression analysis also showed a decrease in malaria prevalence with altitude (IRR: 0.73; 95% CI 0.62–0.86). A significant cluster inland of the district, in rural areas has been found. Conclusions This study reveals a high prevalence of RDT-based malaria among children in Bata district. Those households situated in inland rural areas, near to a river, a green area and/or at low altitude were a risk factor for malaria. Spatial tools can help policy makers to promote new recommendations for malaria control.
Collapse
Affiliation(s)
- Diana Gómez-Barroso
- CIBERESP, National Centre of Epidemiology, Carlos III Institute of Health (ISCIII), Madrid, Spain.
| | - Emely García-Carrasco
- RICET, National Center of Tropical Medicine, Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - Zaida Herrador
- RICET, National Center of Tropical Medicine, Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - Policarpo Ncogo
- Reference Centre for Endemic Control of Equatorial Guinea (CRCE), Malabo, Equatorial Guinea
| | - María Romay-Barja
- RICET, National Center of Tropical Medicine, Carlos III Institute of Health (ISCIII), Madrid, Spain
| | | | - Gloria Nseng
- Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Matilde Riloha
- Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Maria Angeles Santana
- University Institute for Tropical Diseases and Public Health of Canarias, Tenerife, Spain
| | - Basilio Valladares
- University Institute for Tropical Diseases and Public Health of Canarias, Tenerife, Spain
| | - Pilar Aparicio
- RICET, National Center of Tropical Medicine, Carlos III Institute of Health (ISCIII), Madrid, Spain
| | - Agustín Benito
- RICET, National Center of Tropical Medicine, Carlos III Institute of Health (ISCIII), Madrid, Spain
| |
Collapse
|
33
|
Assessing Climate Driven Malaria Variability in Ghana Using a Regional Scale Dynamical Model. CLIMATE 2017. [DOI: 10.3390/cli5010020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
34
|
Shimaponda-Mataa NM, Tembo-Mwase E, Gebreslasie M, Achia TNO, Mukaratirwa S. Modelling the influence of temperature and rainfall on malaria incidence in four endemic provinces of Zambia using semiparametric Poisson regression. Acta Trop 2017; 166:81-91. [PMID: 27829141 DOI: 10.1016/j.actatropica.2016.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 11/03/2016] [Accepted: 11/05/2016] [Indexed: 11/30/2022]
Abstract
Although malaria morbidity and mortality are greatly reduced globally owing to great control efforts, the disease remains the main contributor. In Zambia, all provinces are malaria endemic. However, the transmission intensities vary mainly depending on environmental factors as they interact with the vectors. Generally in Africa, possibly due to the varying perspectives and methods used, there is variation on the relative importance of malaria risk determinants. In Zambia, the role climatic factors play on malaria case rates has not been determined in combination of space and time using robust methods in modelling. This is critical considering the reversal in malaria reduction after the year 2010 and the variation by transmission zones. Using a geoadditive or structured additive semiparametric Poisson regression model, we determined the influence of climatic factors on malaria incidence in four endemic provinces of Zambia. We demonstrate a strong positive association between malaria incidence and precipitation as well as minimum temperature. The risk of malaria was 95% lower in Lusaka (ARR=0.05, 95% CI=0.04-0.06) and 68% lower in the Western Province (ARR=0.31, 95% CI=0.25-0.41) compared to Luapula Province. North-western Province did not vary from Luapula Province. The effects of geographical region are clearly demonstrated by the unique behaviour and effects of minimum and maximum temperatures in the four provinces. Environmental factors such as landscape in urbanised places may also be playing a role.
Collapse
Affiliation(s)
- Nzooma M Shimaponda-Mataa
- University of Zambia, School of Medicine, Department of Biomedical Sciences, Ridgeway Campus, P. O. Box 50110, Lusaka, Zambia; University of KwaZulu-Natal, School of Life Sciences, Westville Campus, Private Bag X54001, Durban 4000, South Africa.
| | - Enala Tembo-Mwase
- University of Zambia, School of Veterinary Medicine, Great East Road Campus, P. O. Box 32379, Lusaka, Zambia
| | - Michael Gebreslasie
- University of KwaZulu-Natal, School of Agriculture, Earth and Environmental Science, Westville Campus, Private Bag X54001, Durban 4000, South Africa
| | - Thomas N O Achia
- University of KwaZulu-Natal School of Mathematics, Statistics and Computer Science, Private Bag X01, Scottsville 3209, Durban, South Africa
| | - Samson Mukaratirwa
- University of KwaZulu-Natal, School of Life Sciences, Westville Campus, Private Bag X54001, Durban 4000, South Africa
| |
Collapse
|
35
|
Marty R, Dolan CB, Leu M, Runfola D. Taking the health aid debate to the subnational level: the impact and allocation of foreign health aid in Malawi. BMJ Glob Health 2017; 2:e000129. [PMID: 28588997 PMCID: PMC5321384 DOI: 10.1136/bmjgh-2016-000129] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/12/2016] [Accepted: 11/03/2016] [Indexed: 01/10/2023] Open
Abstract
Objective Cross-national studies provide inconclusive results as to the effectiveness of foreign health aid. We highlight a novel application of using subnational data to evaluate aid impacts, using Malawi as a case study. Design We employ two rounds of nationally representative household surveys (2004/2005 and 2010/2011) and geo-referenced foreign aid data. We examine the determinants of Malawi's traditional authorities receiving aid according to health, environmental risk, socioeconomic and political factors. We use two approaches to estimate the impact of aid on reducing malaria prevalence and increasing healthcare quality: difference-in-difference models, which include traditional authority and month-of-interview fixed effects and control for individual and household level time-varying factors, and entropy balancing, where models balance on health-related and socioeconomic baseline characteristics. General health aid and four specific health aid sectors are examined. Results Traditional authorities with greater proportions of individuals living in urban areas, more health facilities and greater proportions of those in major ethnic groups were more likely to receive aid. Difference-in-difference models show health infrastructure and parasitic disease control aid reduced malaria prevalence by 1.20 (95% CI −0.36 to 2.76) and 2.20 (95% CI 0.43 to 3.96) percentage points, respectively, and increased the likelihood of individuals reporting healthcare as more than adequate by 12.1 (95% CI 1.51 to 22.68) and 14.0 (95% CI 0.11 to 28.11) percentage points. Entropy balancing shows similar results. Conclusions Aid was targeted to areas with greater existing health infrastructure rather than areas most in need, but still effectively reduced malaria prevalence and enhanced self-reported healthcare quality.
Collapse
Affiliation(s)
- Robert Marty
- AidData, The College of William and Mary, Williamsburg, Virginia, USA
| | - Carrie B Dolan
- AidData, The College of William and Mary, Williamsburg, Virginia, USA
| | - Matthias Leu
- Department of Biology, The College of William and Mary, Williamsburg, Virginia, USA
| | - Daniel Runfola
- AidData, The College of William and Mary, Williamsburg, Virginia, USA
| |
Collapse
|
36
|
Moise IK, Kalipeni E, Jusrut P, Iwelunmor JI. Assessing the reduction in infant mortality rates in Malawi over the 1990–2010 decades. Glob Public Health 2016; 12:757-779. [DOI: 10.1080/17441692.2016.1239268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Imelda K. Moise
- Department of Geography and Regional Studies, University of Miami, Coral Gables, FL, USA
| | - Ezekiel Kalipeni
- Department of Geography & GIScience, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Poonam Jusrut
- Department of Geography & GIScience, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Juliet I. Iwelunmor
- Department of Kinesiology and Community Health, College of Applied Health Sciences, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| |
Collapse
|
37
|
Okami S, Kohtake N. Fine-Scale Mapping by Spatial Risk Distribution Modeling for Regional Malaria Endemicity and Its Implications under the Low-to-Moderate Transmission Setting in Western Cambodia. PLoS One 2016; 11:e0158737. [PMID: 27415623 PMCID: PMC4944927 DOI: 10.1371/journal.pone.0158737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 06/21/2016] [Indexed: 11/18/2022] Open
Abstract
The disease burden of malaria has decreased as malaria elimination efforts progress. The mapping approach that uses spatial risk distribution modeling needs some adjustment and reinvestigation in accordance with situational changes. Here we applied a mathematical modeling approach for standardized morbidity ratio (SMR) calculated by annual parasite incidence using routinely aggregated surveillance reports, environmental data such as remote sensing data, and non-environmental anthropogenic data to create fine-scale spatial risk distribution maps of western Cambodia. Furthermore, we incorporated a combination of containment status indicators into the model to demonstrate spatial heterogeneities of the relationship between containment status and risks. The explanatory model was fitted to estimate the SMR of each area (adjusted Pearson correlation coefficient R2 = 0.774; Akaike information criterion AIC = 149.423). A Bayesian modeling framework was applied to estimate the uncertainty of the model and cross-scale predictions. Fine-scale maps were created by the spatial interpolation of estimated SMRs at each village. Compared with geocoded case data, corresponding predicted values showed conformity [Spearman’s rank correlation r = 0.662 in the inverse distance weighed interpolation and 0.645 in ordinal kriging (95% confidence intervals of 0.414–0.827 and 0.368–0.813, respectively), Welch’s t-test; Not significant]. The proposed approach successfully explained regional malaria risks and fine-scale risk maps were created under low-to-moderate malaria transmission settings where reinvestigations of existing risk modeling approaches were needed. Moreover, different representations of simulated outcomes of containment status indicators for respective areas provided useful insights for tailored interventional planning, considering regional malaria endemicity.
Collapse
Affiliation(s)
- Suguru Okami
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
- * E-mail:
| | - Naohiko Kohtake
- Graduate School of System Design and Management, Keio University, Kanagawa, Japan
| |
Collapse
|
38
|
Ebhuoma O, Gebreslasie M. Remote Sensing-Driven Climatic/Environmental Variables for Modelling Malaria Transmission in Sub-Saharan Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:ijerph13060584. [PMID: 27314369 PMCID: PMC4924041 DOI: 10.3390/ijerph13060584] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 06/02/2016] [Accepted: 06/08/2016] [Indexed: 11/16/2022]
Abstract
Malaria is a serious public health threat in Sub-Saharan Africa (SSA), and its transmission risk varies geographically. Modelling its geographic characteristics is essential for identifying the spatial and temporal risk of malaria transmission. Remote sensing (RS) has been serving as an important tool in providing and assessing a variety of potential climatic/environmental malaria transmission variables in diverse areas. This review focuses on the utilization of RS-driven climatic/environmental variables in determining malaria transmission in SSA. A systematic search on Google Scholar and the Institute for Scientific Information (ISI) Web of Knowledge(SM) databases (PubMed, Web of Science and ScienceDirect) was carried out. We identified thirty-five peer-reviewed articles that studied the relationship between remotely-sensed climatic variable(s) and malaria epidemiological data in the SSA sub-regions. The relationship between malaria disease and different climatic/environmental proxies was examined using different statistical methods. Across the SSA sub-region, the normalized difference vegetation index (NDVI) derived from either the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) or Moderate-resolution Imaging Spectrometer (MODIS) satellite sensors was most frequently returned as a statistically-significant variable to model both spatial and temporal malaria transmission. Furthermore, generalized linear models (linear regression, logistic regression and Poisson regression) were the most frequently-employed methods of statistical analysis in determining malaria transmission predictors in East, Southern and West Africa. By contrast, multivariate analysis was used in Central Africa. We stress that the utilization of RS in determining reliable malaria transmission predictors and climatic/environmental monitoring variables would require a tailored approach that will have cognizance of the geographical/climatic setting, the stage of malaria elimination continuum, the characteristics of the RS variables and the analytical approach, which in turn, would support the channeling of intervention resources sustainably.
Collapse
Affiliation(s)
- Osadolor Ebhuoma
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa.
| | - Michael Gebreslasie
- School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Westville Campus, Durban 4000, South Africa.
| |
Collapse
|
39
|
Mukomena SE, Philipe CM, Désiré MK, Pascal LT, Ali MM, Oscar LN. [Asymptomatic Parasitemia in under five, school age children and households self-medication, Lubumbashi, Democratic Republic of Congo]. Pan Afr Med J 2016; 24:94. [PMID: 27642433 PMCID: PMC5012784 DOI: 10.11604/pamj.2016.24.94.9350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/26/2016] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION Long neglected, asymptomatic malaria is currently recognized as a potential threat and obstacle to malaria control. In DR Congo, the prevalence of this parasite is poorly documented. This study aims to determine the prevalence of asymptomatic parasitaemia in children less than 5 years of age as well as in those aged over five years for what concerns ongoing mass control interventions (LLINs). METHODS This is a cross-sectional study conducted among school age children, children less than 5 years of age living in the household of Lubumbashi. Schools, students and children less than 5 years of age were selected randomly. Thick and thin blood smears and rapid tests were performed and read. RESULTS Out of 350 examined students, 43 (12, 3%), IC 95% (9, 14-16, 04) had positive thick smear. Only plasmodium falciparum was identified in all the 43 cases. 314 households (90.5%) declared that they had administered anti-malarial drugs to their children to treat fever at home. More than one-third of households (39.9%) declared that they had administered antipyretics to their children to relieve fever, 19.7% administered quinine and only less than 2% artemether-lumefantrine. Considering the use of the TDR technique, the prevalence of asymptomatic parasitaemia was 3%, IC 95% (from 2.075 to 4.44), but if we consider microscopy as the gold standard, the prevalence was 1.9%, IC 95% (from 1.13 to 3.01). CONCLUSION Asymptomatic malaria is not without health consequences, so it is important to conduct such investigations to detect new malaria device programmes.
Collapse
Affiliation(s)
- Sompwe Eric Mukomena
- Département de Santé Publique, Faculté de Médecine, Université de Lubumbashi, République Démocratique du Congo; Ecole de Santé Publique, Université de Lubumbashi, République Démocratique du Congo
| | - Cilundika Mulenga Philipe
- Département de Santé Publique, Faculté de Médecine, Université de Lubumbashi, République Démocratique du Congo
| | | | - Lutumba Tshindele Pascal
- Département de Médecine Tropicale, Faculté de Médecine, Université de Kinshasa, République Démocratique du Congo
| | - Mapatano Mala Ali
- Ecole de Santé Publique, Université de Kinshasa, République Démocratique du Congo
| | - Luboya Numbi Oscar
- Département de Santé Publique, Faculté de Médecine, Université de Lubumbashi, République Démocratique du Congo; Ecole de Santé Publique, Université de Lubumbashi, République Démocratique du Congo
| |
Collapse
|
40
|
Izadi S. The effects of electricity network development besides routine malaria control measures in an underdeveloped region in the pre-elimination phase. Malar J 2016; 15:222. [PMID: 27091331 PMCID: PMC4835824 DOI: 10.1186/s12936-016-1273-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 04/03/2016] [Indexed: 11/22/2022] Open
Abstract
Background The main purpose of this study was to investigate the effects of electricity network development on malaria transmission. The study was performed in the rural areas of three districts in Sistan-va-Baluchestan Province, Iran. Methods From the mentioned districts, 122 rural communities were selected. The data of the years 2005–2009 were collected retrospectively from data banks of the district health centres and the offices of the local electricity network. Fixed and random effects panel data regression models were fitted to determine the effects of electrification and other variables on malaria transmission during the elimination phase. Results It seems that access to electricity of rural communities, if not harmful, has no obvious effect on malaria control and prevention at least during the elimination phase in an underdeveloped region. Elevation above sea level and precipitation during spring and summer were found to be the other important, respectively, time-invariant and time-dependent variables associated with decreasing and increasing malaria transmission. Indoor residual spraying and the use of insecticide-treated mosquito nets were not found to be effective in decreasing malaria transmission in the elimination phase. Conclusions The introduction of electricity to a rural community does not guarantee an absolutely good effect on the reduction of malaria transmission.
Collapse
Affiliation(s)
- Shahrokh Izadi
- Health Promotion Research Centre, School of Public Health, Zahedan University of Medical Sciences, Zahedan, P.O. Box 98155-759, Iran.
| |
Collapse
|
41
|
Hanandita W, Tampubolon G. Geography and social distribution of malaria in Indonesian Papua: a cross-sectional study. Int J Health Geogr 2016; 15:13. [PMID: 27072128 PMCID: PMC4830039 DOI: 10.1186/s12942-016-0043-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/30/2016] [Indexed: 11/10/2022] Open
Abstract
Background Despite being one of the world’s most affected regions, only little is known about the social and spatial distributions of malaria in Indonesian Papua. Existing studies tend to be descriptive in nature; their inferences are prone to confounding and selection biases. At the same time, there remains limited malaria-cartographic activity in the region. Analysing a subset (N = 22,643) of the National Basic Health Research 2007 dataset (N = 987,205), this paper aims to quantify the district-specific risk of malaria in Papua and to understand how socio-demographic/economic factors measured at individual and district levels are associated with individual’s probability of contracting the disease. Methods We adopt a Bayesian hierarchical logistic regression model that accommodates not only the nesting of individuals within the island’s 27 administrative units but also the spatial autocorrelation among these locations. Both individual and contextual characteristics are included as predictors in the model; a normal conditional autoregressive prior and an exchangeable one are assigned to the random effects. Robustness is then assessed through sensitivity analyses using alternative hyperpriors. Results We find that rural Papuans as well as those who live in poor, densely forested, lowland districts are at a higher risk of infection than their counterparts. We also find age and gender differentials in malaria prevalence, if only to a small degree. Nine districts are estimated to have higher-than-expected malaria risks; the extent of spatial variation on the island remains notable even after accounting for socio-demographic/economic risk factors. Conclusions Although we show that malaria is geography-dependent in Indonesian Papua, it is also a disease of poverty. This means that malaria eradication requires not only biological (proximal) interventions but also social (distal) ones.
Collapse
Affiliation(s)
- Wulung Hanandita
- Cathie Marsh Institute for Social Research (CMIST), University Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - Gindo Tampubolon
- Cathie Marsh Institute for Social Research (CMIST), University Manchester, Oxford Road, Manchester, M13 9PL, UK
| |
Collapse
|
42
|
A Regional Model for Malaria Vector Developmental Habitats Evaluated Using Explicit, Pond-Resolving Surface Hydrology Simulations. PLoS One 2016; 11:e0150626. [PMID: 27003834 PMCID: PMC4803214 DOI: 10.1371/journal.pone.0150626] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 02/17/2016] [Indexed: 11/26/2022] Open
Abstract
Dynamical malaria models can relate precipitation to the availability of vector breeding sites using simple models of surface hydrology. Here, a revised scheme is developed for the VECTRI malaria model, which is evaluated alongside the default scheme using a two year simulation by HYDREMATS, a 10 metre resolution, village-scale model that explicitly simulates individual ponds. Despite the simplicity of the two VECTRI surface hydrology parametrization schemes, they can reproduce the sub-seasonal evolution of fractional water coverage. Calibration of the model parameters is required to simulate the mean pond fraction correctly. The default VECTRI model tended to overestimate water fraction in periods subject to light rainfall events and underestimate it during periods of intense rainfall. This systematic error was improved in the revised scheme by including the a parametrization for surface run-off, such that light rainfall below the initial abstraction threshold does not contribute to ponds. After calibration of the pond model, the VECTRI model was able to simulate vector densities that compared well to the detailed agent based model contained in HYDREMATS without further parameter adjustment. Substituting local rain-gauge data with satellite-retrieved precipitation gave a reasonable approximation, raising the prospects for regional malaria simulations even in data sparse regions. However, further improvements could be made if a method can be derived to calibrate the key hydrology parameters of the pond model in each grid cell location, possibly also incorporating slope and soil texture.
Collapse
|
43
|
Sena L, Deressa W, Ali A. Correlation of Climate Variability and Malaria: A Retrospective Comparative Study, Southwest Ethiopia. Ethiop J Health Sci 2016; 25:129-38. [PMID: 26124620 PMCID: PMC4478264 DOI: 10.4314/ejhs.v25i2.5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Background Climatic variables can determine malaria transmission dynamics. To see the correlation between malaria occurrence and climatic variables, records of malaria episodes over eight years period were analyzed incorporating climatic variables around Gilgel-Gibe Hydroelectric Dam and control sites. Methods Records of 99,206 confirmed malaria episodes registered between 2003 and 2011 were analyzed along with local meteorological data of the same duration. Data were analyzed with SPSS statistical software version 20 for Windows. Spearman correlation coefficient was estimated as a measure of the correlation. Results The major peaks of malaria prevalence were observed following the peaks of rainfall in the Gilgel-Gibe Hydroelectric Dam site. In the control site, the peaks of malaria in some years coincided with the peaks of rainfall, and the pattern of rainfall was relatively less fluctuating. Mean rainfall was negatively correlated with number of malaria cases at lags of 0 and 1 month, but positively correlated at lags of 2 to 4 months. Mean relative humidity showed significant positive correlations at lags of 3 to 4 months. Monthly mean maximum and minimum temperatures weakly correlated at lags of 0 to 4 months. Conclusions Correlations of malaria and climate variables were different for the two sites; in Gilgel-Gibe, rainfall and relative humidity showed positive correlations. However, in the control site, the correlation of weather variables and malaria episodes were insignificant. Exploration of additional factors such as vegetation index and physico-chemical nature of mosquito breeding site may improve understanding of determinants of malaria dynamics in the area.
Collapse
Affiliation(s)
- Lelisa Sena
- Department of Epidemiology, College of Public Health and Medical Sciences, Jimma University, Ethiopia ; Department of Preventive Medicine, School of Public Health, College of Health Sciences, Addis Ababa University, Ethiopia
| | - Wakgari Deressa
- Department of Preventive Medicine, School of Public Health, College of Health Sciences, Addis Ababa University, Ethiopia
| | - Ahmed Ali
- Department of Preventive Medicine, School of Public Health, College of Health Sciences, Addis Ababa University, Ethiopia
| |
Collapse
|
44
|
Chihanga S, Haque U, Chanda E, Mosweunyane T, Moakofhi K, Jibril HB, Motlaleng M, Zhang W, Glass GE. Malaria elimination in Botswana, 2012-2014: achievements and challenges. Parasit Vectors 2016; 9:99. [PMID: 26911433 PMCID: PMC4765051 DOI: 10.1186/s13071-016-1382-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 02/16/2016] [Indexed: 12/25/2022] Open
Abstract
Background Botswana significantly reduced its malaria burden between 2000 and 2012. Incidence dropped from 0.99 to 0.01 % and deaths attributed to malaria declined from 12 to 3. The country initiated elimination strategies in October 2012. We examine the progress and challenges during implementation and identify future needs for a successful program in Botswana. Methods A national, rapid notification and response strategy was developed. Cases detected through the routine passive surveillance system at health facilities were intended to initiate screening of contacts around a positive case during follow up. Positive cases were reported to district health management teams to activate district rapid response teams (DRRT). The health facility and the DRRT were to investigate the cases, and screen household members within 100 m of case households within 48 h of notification using rapid diagnostic tests (RDT) and microscopy. Positive malaria cases detected in health facilities were used for spatial analysis. Results There were 1808 malaria cases recorded in Botswana during 26 months from October, 2012 to December, 2014. Males were more frequently infected (59 %) than females. Most cases (60 %) were reported from Okavango district which experienced an outbreak in 2013 and 2014. Among the factors creating challenges for malaria eradication, only 1148 cases (63.5 %) were captured by the required standardized notification forms. In total, 1080 notified cases were diagnosed by RDT. Of the positive malaria cases, only 227 (12.6 %) were monitored at the household level. One hundred (8.7 %) cases were associated with national or transnational movement of patients. Local movements of infected individuals within Botswana accounted for 31 cases while 69 (6.01 %) cases were imported from other countries. Screening individuals in and around index households identified 37 additional, asymptomatic infections. Oscillating, sporadic and new malaria hot-spots were detected in Botswana during the study period. Conclusion Botswana’s experience shows some of the practical challenges of elimination efforts. Among them are the substantial movements of human infections within and among countries, and the persistence of asymptomatic reservoir infections. Programmatically, challenges include improving the speed of communicating and improving the thoroughness when responding to newly identified cases. The country needs further sustainable interventions to target infections if it is to successfully achieve its elimination goal.
Collapse
Affiliation(s)
- Simon Chihanga
- National Malaria Programme, Ministry of Health, Gaborone, Botswana.
| | - Ubydul Haque
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA. .,Department of Geography, University of Florida, Gainesville, Florida, USA.
| | - Emmanuel Chanda
- Vector Control Specialist/Consultant, 11 Granite Street, Plot 33421/917 Kamwa South, Lusaka, Zambia.
| | | | | | | | - Mpho Motlaleng
- National Malaria Programme, Ministry of Health, Gaborone, Botswana.
| | - Wenyi Zhang
- Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, People's Republic of China.
| | - Gregory E Glass
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA. .,Department of Geography, University of Florida, Gainesville, Florida, USA.
| |
Collapse
|
45
|
Lal A. Spatial Modelling Tools to Integrate Public Health and Environmental Science, Illustrated with Infectious Cryptosporidiosis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:186. [PMID: 26848669 PMCID: PMC4772206 DOI: 10.3390/ijerph13020186] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/11/2016] [Accepted: 01/26/2016] [Indexed: 01/12/2023]
Abstract
Contemporary spatial modelling tools can help examine how environmental exposures such as climate and land use together with socio-economic factors sustain infectious disease transmission in humans. Spatial methods can account for interactions across global and local scales, geographic clustering and continuity of the exposure surface, key characteristics of many environmental influences. Using cryptosporidiosis as an example, this review illustrates how, in resource rich settings, spatial tools have been used to inform targeted intervention strategies and forecast future disease risk with scenarios of environmental change. When used in conjunction with molecular studies, they have helped determine location-specific infection sources and environmental transmission pathways. There is considerable scope for such methods to be used to identify data/infrastructure gaps and establish a baseline of disease burden in resource-limited settings. Spatial methods can help integrate public health and environmental science by identifying the linkages between the physical and socio-economic environment and health outcomes. Understanding the environmental and social context for disease spread is important for assessing the public health implications of projected environmental change.
Collapse
Affiliation(s)
- Aparna Lal
- National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Acton, Canberra 2602, Australia.
| |
Collapse
|
46
|
Modelling Climate-Sensitive Disease Risk: A Decision Support Tool for Public Health Services. ACTA ACUST UNITED AC 2016. [DOI: 10.1007/978-3-319-20161-0_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
|
47
|
Chitunhu S, Musenge E. Spatial and socio-economic effects on malaria morbidity in children under 5 years in Malawi in 2012. Spat Spatiotemporal Epidemiol 2015; 16:21-33. [PMID: 26919752 DOI: 10.1016/j.sste.2015.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 10/22/2015] [Accepted: 11/04/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Malaria is a major health challenge in sub-Saharan Africa with children under 5 being most vulnerable. Identifying regions of greater malarial burden is vital in targeting interventions. METHODS This study analysed malaria morbidity using data from the Malawi 2012 Malaria Indicator Survey that were obtained from Demographic and Health Survey (DHS) program website. These data captured malaria related information on children under 5. Poisson regression was done to determine associations between outcome (number of children under 5 with malaria in household) and explanatory variables. A Bayesian smoothing approach was employed to adjust for spatial random effects on child related variables. RESULTS There were 1878 households in 140 clusters. The number of children under five was 1900. Spatially structured effects accounted for more than 90% of random effects as these had a mean of 1.32 (95% Credible Interval (CI)=0.37, 2.50) whilst spatially unstructured had a mean of 0.10 (CI=9.0 × 10(-4), 0.38). Spatially adjusted significant variables were; type of place of residence (urban or rural) [posterior odds ratio (POR)=2.06; CI= 1.27, 3.34], not owning land [POR=1.77; CI=1.19, 2.64], not staying in a slum [POR=0.52; CI=0.33, 0.83] and enhanced vegetation index [POR=0.02; CI=0.00, 1.08]. A trend was observed on usage of insecticide treated mosquito nets [POR=0.80; CI=0.63, 1.03]. CONCLUSION This study showed that malaria is a disease of poverty. Enhanced vegetation index was an important factor in malaria morbidity. The central region was identified as the area with greatest disease burden.
Collapse
Affiliation(s)
- Simangaliso Chitunhu
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg 2193, South Africa.
| | - Eustasius Musenge
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg 2193, South Africa.
| |
Collapse
|
48
|
Chitunhu S, Musenge E. Direct and indirect determinants of childhood malaria morbidity in Malawi: a survey cross-sectional analysis based on malaria indicator survey data for 2012. Malar J 2015; 14:265. [PMID: 26152223 PMCID: PMC4495946 DOI: 10.1186/s12936-015-0777-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/29/2015] [Indexed: 01/06/2023] Open
Abstract
Background Children under the age of five are most vulnerable to malaria (malaria is a major health challenge in sub-Saharan Africa) with a child dying every 30 s from malaria. Hampered socio-economic development, poverty, diseconomies of scale, marginalization, and exploitation are associated with malaria. Therefore establishing determinants of malaria in affected sub-Saharan populations is important in order to come up with informed interventions that will be effective in malaria control. Methods The study was a cross-sectional survey design based on data from the Malawi 2012 Malaria indicator Survey obtained from Demographic and Health Survey (DHS) programme website. The outcome variable was positive laboratory-based blood smear result for malaria in children less than 5 years, after an initial positive rapid malaria diagnostic test done at the homestead. Statistical modelling was done using survey logistic regression as well as generalized structural equation modelling (G-SEM) to analyse direct and indirect effects of malaria. Results The propensity score matched data had 1 325 children with 367 (27.7%) having blood smear positive malaria. Female children made up approximately 53% of the total study participants. Child related variables (age, haemoglobin and position in household) and household wealth index were significant directly and indirectly. Further on G-SEM based multivariable analysis showed socio-economic status (SES) [Odds ratio (OR) = 0.96, 95% Confidence interval (CI) = 0.92, 0.99] and primary level of education [OR = 0.50, 95% CI = 0.32, 0.77] were important direct and indirect determinants of malaria morbidity. Conclusion Socio-economic status and education are important factors that influence malaria control. These factors need to be taken into consideration when planning malaria control programmes in order to have effective programmes. Direct and indirect effect modelling can also provide an alternative modelling technique that incorporates surrogate confounders that may not be significant when modelled directly. This holistic approach is useful and will help in improving malaria control.
Collapse
Affiliation(s)
- Simangaliso Chitunhu
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg, 2193, South Africa.
| | - Eustasius Musenge
- Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews' Road, Parktown, Johannesburg, 2193, South Africa.
| |
Collapse
|
49
|
Chirombo J, Lowe R, Kazembe L. Using structured additive regression models to estimate risk factors of malaria: analysis of 2010 Malawi malaria indicator survey data. PLoS One 2014; 9:e101116. [PMID: 24991915 PMCID: PMC4084636 DOI: 10.1371/journal.pone.0101116] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 06/03/2014] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND After years of implementing Roll Back Malaria (RBM) interventions, the changing landscape of malaria in terms of risk factors and spatial pattern has not been fully investigated. This paper uses the 2010 malaria indicator survey data to investigate if known malaria risk factors remain relevant after many years of interventions. METHODS We adopted a structured additive logistic regression model that allowed for spatial correlation, to more realistically estimate malaria risk factors. Our model included child and household level covariates, as well as climatic and environmental factors. Continuous variables were modelled by assuming second order random walk priors, while spatial correlation was specified as a Markov random field prior, with fixed effects assigned diffuse priors. Inference was fully Bayesian resulting in an under five malaria risk map for Malawi. RESULTS Malaria risk increased with increasing age of the child. With respect to socio-economic factors, the greater the household wealth, the lower the malaria prevalence. A general decline in malaria risk was observed as altitude increased. Minimum temperatures and average total rainfall in the three months preceding the survey did not show a strong association with disease risk. CONCLUSIONS The structured additive regression model offered a flexible extension to standard regression models by enabling simultaneous modelling of possible nonlinear effects of continuous covariates, spatial correlation and heterogeneity, while estimating usual fixed effects of categorical and continuous observed variables. Our results confirmed that malaria epidemiology is a complex interaction of biotic and abiotic factors, both at the individual, household and community level and that risk factors are still relevant many years after extensive implementation of RBM activities.
Collapse
Affiliation(s)
- James Chirombo
- Chancellor College, University of Malawi, Zomba, Malawi
- UNC Project, Lilongwe, Malawi
| | - Rachel Lowe
- Institut Català de Ciències del Clima (IC3), Barcelona, Spain
- Abdus Salam International Centre for Theoretical Physics, Trieste, Italy
| | - Lawrence Kazembe
- Department of Statistics and Population Studies, University of Namibia, Windhoek, Namibia
| |
Collapse
|