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Zhou G, Lee MC, Wang X, Zhong D, Githeko AK, Yan G. Mapping Potential Malaria Vector Larval Habitats for Larval Source Management in Western Kenya: Introduction to Multimodel Ensembling Approaches. Am J Trop Med Hyg 2024; 110:421-430. [PMID: 38350135 PMCID: PMC10919169 DOI: 10.4269/ajtmh.23-0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 11/03/2023] [Indexed: 02/15/2024] Open
Abstract
Identification and mapping of larval sources are a prerequisite for effective planning and implementing mosquito larval source management (LSM). Ensemble modeling is increasingly used for prediction modeling, but it lacks standard procedures. We proposed a detailed framework to predict potential malaria vector larval habitats by using multimodel ensemble modeling, which includes selection of models, ensembling method, and predictors, evaluation of variable importance, prediction of potential larval habitats, and assessment of prediction uncertainty. The models were built and validated based on multisite, multiyear field observations and climatic/environmental variables. Model performance was tested using independent field observations. Overall, we found that the ensembled model predicted larval habitats with about 20% more accuracy than the average of the individual models ensembled. Key larval habitat predictors in western Kenya were elevation, geomorphon class, and precipitation for the 2 months prior. Additional predictors may be required to increase the predictive accuracy of the larva-positive habitats. This is the first study to provide a detailed framework for the process of multimodel ensemble modeling for malaria vector habitats. Mapping of potential habitats will be helpful in LSM planning.
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Affiliation(s)
- Guofa Zhou
- Program in Public Health, University of California, Irvine, California
| | - Ming-Chieh Lee
- Program in Public Health, University of California, Irvine, California
| | - Xiaoming Wang
- Program in Public Health, University of California, Irvine, California
| | - Daibin Zhong
- Program in Public Health, University of California, Irvine, California
| | - Andrew K. Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, California
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Manley W, Tran T, Prusinski M, Brisson D. Modeling Tick Populations: An Ecological Test Case for Gradient Boosted Trees. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532443. [PMID: 36993623 PMCID: PMC10054924 DOI: 10.1101/2023.03.13.532443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
General linear models have been the foundational statistical framework used to discover the ecological processes that explain the distribution and abundance of natural populations. Analyses of the rapidly expanding cache of environmental and ecological data, however, require advanced statistical methods to contend with complexities inherent to extremely large natural data sets. Modern machine learning frameworks such as gradient boosted trees efficiently identify complex ecological relationships in massive data sets, which are expected to result in accurate predictions of the distribution and abundance of organisms in nature. However, rigorous assessments of the theoretical advantages of these methodologies on natural data sets are rare. Here we compare the abilities of gradient boosted and linear models to identify environmental features that explain observed variations in the distribution and abundance of blacklegged tick (Ixodes scapularis) populations in a data set collected across New York State over a ten-year period. The gradient boosted and linear models use similar environmental features to explain tick demography, although the gradient boosted models found non-linear relationships and interactions that are difficult to anticipate and often impractical to identify with a linear modeling framework. Further, the gradient boosted models predicted the distribution and abundance of ticks in years and areas beyond the training data with much greater accuracy than their linear model counterparts. The flexible gradient boosting framework also permitted additional model types that provide practical advantages for tick surveillance and public health. The results highlight the potential of gradient boosted models to discover novel ecological phenomena affecting pathogen demography and as a powerful public health tool to mitigate disease risks.
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Kalthof MWML, Gravey M, Wijnands F, Karssenberg D. Predicting Continental Scale Malaria With Land Surface Water Predictors Based on Malaria Dispersal Mechanisms and High-Resolution Earth Observation Data. GEOHEALTH 2023; 7:e2023GH000811. [PMID: 37822333 PMCID: PMC10564405 DOI: 10.1029/2023gh000811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/24/2023] [Accepted: 08/28/2023] [Indexed: 10/13/2023]
Abstract
Despite malaria prevalence being linked to surface water through vector breeding, spatial malaria predictors representing surface water often predict malaria poorly. Furthermore, precipitation, which precursors surface water, often performs better. Our goal is to determine whether novel surface water exposure indices that take malaria dispersal mechanisms into account, derived from new high-resolution surface water data, can be stronger predictors of malaria prevalence compared to precipitation. One hundred eighty candidate predictors were created by combining three surface water malaria exposures from high-accuracy and resolution (5 m resolution, overall accuracy 96%, Kappa Coefficient 0.89, Commission and Omission error 3% and 13%, respectively) water maps of East Africa. Through variable contribution analysis a subset of strong predictors was selected and used as input for Boosted Regression Tree models. We benchmarked the performance and Relative Contribution of this set of novel predictors to models using precipitation instead of surface water predictors, alternative lower resolution predictors, and simpler surface water predictors used in previous studies. The predictive performance of the novel indices rivaled or surpassed that of precipitation predictors. The novel indices substantially improved performance over the identical set of predictors derived from the lower resolution Joint Research Center surface water data set (+10% R 2, +17% Relative Contribution) and over the set of simpler predictors (+18% R 2, +30% Relative Contribution). Surface water derived indices can be strong predictors of malaria, if the spatial resolution is sufficiently high to detect small waterbodies and dispersal mechanisms of malaria related to surface water in human and vector water exposure assessment are incorporated.
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Affiliation(s)
- Maurice W. M. L. Kalthof
- Institute for Environmental Studies (IVM)Vrije Universiteit AmsterdamAmsterdamThe Netherlands
- Department of Physical GeographyUtrecht UniversityUtrechtThe Netherlands
| | - Mathieu Gravey
- Institute for Interdisciplinary Mountain ResearchÖsterreichische Akademie der WissenschaftenInnsbruckAustria
| | - Flore Wijnands
- Institutionen för Geologiska VetenskaperStockholm UniversityStockholmSweden
| | - Derek Karssenberg
- Department of Physical GeographyUtrecht UniversityUtrechtThe Netherlands
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Conn JE, Bickersmith SA, Saavedra MP, Morales JA, Alava F, Diaz Rodriguez GA, del Aguila Morante CR, Tong CG, Alvarez-Antonio C, Daza Huanahui JM, Vinetz JM, Gamboa D. Natural Infection of Nyssorhynchus darlingi and Nyssorhynchus benarrochi B with Plasmodium during the Dry Season in the Understudied Low-Transmission Setting of Datem del Marañon Province, Amazonian Peru. Am J Trop Med Hyg 2023; 109:288-295. [PMID: 37364858 PMCID: PMC10397451 DOI: 10.4269/ajtmh.23-0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 04/25/2023] [Indexed: 06/28/2023] Open
Abstract
The persistence of malaria hotspots in Datem del Marañon Province, Peru, prompted vector control units at the Ministry of Health, Loreto Department, to collaborate with the Amazonian International Center of Excellence for Malaria Research to identify the main vectors in several riverine villages that had annual parasite indices > 15 in 2018-2019. Anophelinae were collected indoors and outdoors for two 12-hour nights/community during the dry season in 2019 using human landing catch. We identified four species: Nyssorhynchus benarrochi B, Nyssorhynchus darlingi, Nyssorhynchus triannulatus, and Anopheles mattogrossensis. The most abundant, Ny. benarrochi B, accounted for 96.3% of the total (7,550/7,844), of which 61.5% were captured outdoors (4,641/7,550). Six mosquitoes, one Ny. benarrochi B and five Ny. darlingi, were infected by Plasmodium falciparum or Plasmodium vivax. Human biting rates ranged from 0.5 to 592.8 bites per person per hour for Ny. benarrochi B and from 0.5 to 32.0 for Ny. darlingi, with entomological inoculation rates as high as 0.50 infective bites per night for Ny. darlingi and 0.25 for Ny. benarrochi B. These data demonstrate the risk of malaria transmission by both species even during the dry season in villages in multiple watersheds in Datem del Marañon province.
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Affiliation(s)
- Jan E. Conn
- Wadsworth Center, New York State Department of Health, Albany, New York
- Department of Biomedical Sciences, School of Public Health, State University of New York-Albany, Albany, New York
| | | | - Marlon P. Saavedra
- Amazonian International Center of Excellence for Malaria Research, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Juliana A. Morales
- Amazonian International Center of Excellence for Malaria Research, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | | | | | - Carlos G. Tong
- Laboratorio de Salud Pública-Gerencia Regional de Salud de Loreto, GERESA, Iquitos, Peru
| | | | - Jesus M. Daza Huanahui
- Red de Salud Datem del Marañon – Gerencia Regional de Salud de Loreto, GERESA, Iquitos, Peru
| | - Joseph M. Vinetz
- Amazonian International Center of Excellence for Malaria Research, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorio de Malaria: Parásitos y Vectores, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
- VA Connecticut Healthcare System, West Haven, Connecticut
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Dionicia Gamboa
- Amazonian International Center of Excellence for Malaria Research, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorio de Malaria: Parásitos y Vectores, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
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Hollingsworth BD, Sandborn H, Baguma E, Ayebare E, Ntaro M, Mulogo EM, Boyce RM. Comparing field-collected versus remotely-sensed variables to model malaria risk in the highlands of western Uganda. Malar J 2023; 22:197. [PMID: 37365595 PMCID: PMC10294526 DOI: 10.1186/s12936-023-04628-w] [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] [Accepted: 06/16/2023] [Indexed: 06/28/2023] Open
Abstract
BACKGROUND Malaria risk is not uniform across relatively small geographic areas, such as within a village. This heterogeneity in risk is associated with factors including demographic characteristics, individual behaviours, home construction, and environmental conditions, the importance of which varies by setting, making prediction difficult. This study attempted to compare the ability of statistical models to predict malaria risk at the household level using either (i) free easily-obtained remotely-sensed data or (ii) results from a resource-intensive household survey. METHODS The results of a household malaria survey conducted in 3 villages in western Uganda were combined with remotely-sensed environmental data to develop predictive models of two outcomes of interest (1) a positive ultrasensitive rapid diagnostic test (uRDT) and (2) inpatient admission for malaria within the last year. Generalized additive models were fit to each result using factors from the remotely-sensed data, the household survey, or a combination of both. Using a cross-validation approach, each model's ability to predict malaria risk for out-of-sample households (OOS) and villages (OOV) was evaluated. RESULTS Models fit using only environmental variables provided a better fit and higher OOS predictive power for uRDT result (AIC = 362, AUC = 0.736) and inpatient admission (AIC = 623, AUC = 0.672) compared to models using household variables (uRDT AIC = 376, Admission AIC = 644, uRDT AUC = 0.667, Admission AUC = 0.653). Combining the datasets did not result in a better fit or higher OOS predictive power for uRDT results (AIC = 367, AUC = 0.671), but did for inpatient admission (AIC = 615, AUC = 0.683). Household factors performed best when predicting OOV uRDT results (AUC = 0.596) and inpatient admission (AUC = 0.553), but not much better than a random classifier. CONCLUSIONS These results suggest that residual malaria risk is driven more by the external environment than home construction within the study area, possibly due to transmission regularly occurring outside of the home. Additionally, they suggest that when predicting malaria risk the benefit may not outweigh the high costs of attaining detailed information on household predictors. Instead, using remotely-sensed data provides an equally effective, cost-efficient alternative.
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Affiliation(s)
| | - Hilary Sandborn
- Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Emmanuel Baguma
- Department of Community Health, Faculty of Medicine, Mbarara University of Science & Technology, Mbarara, Uganda
| | - Emmanuel Ayebare
- Department of Community Health, Faculty of Medicine, Mbarara University of Science & Technology, Mbarara, Uganda
| | - Moses Ntaro
- Department of Community Health, Faculty of Medicine, Mbarara University of Science & Technology, Mbarara, Uganda
| | - Edgar M Mulogo
- Department of Community Health, Faculty of Medicine, Mbarara University of Science & Technology, Mbarara, Uganda
| | - Ross M Boyce
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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The urgent need to develop a new grassland map in China: based on the consistency and accuracy of ten land cover products. SCIENCE CHINA. LIFE SCIENCES 2023; 66:385-405. [PMID: 36040706 DOI: 10.1007/s11427-021-2143-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 06/10/2022] [Indexed: 10/14/2022]
Abstract
Grasslands are the most dominant terrestrial ecosystem in China, but few national grassland maps have been generated. The grassland resource map produced in the 1980s is widely used as background data, but it has not been updated for almost 40 years. Therefore, a reliable map depicting the current spatial distribution of grasslands across the country is urgently needed. In this study, we evaluated the grassland consistency and accuracy of ten land cover datasets (GLC2000, GlobCover, CCI-LC, MCD12Q1, CLUD, GlobeLand30, GLC-FCS30, CGLS-LC100, CLCD, and FROM-GLC) for 2000, 2010, and 2020 based on extensive fieldwork. We concluded that the area of these ten grassland products ranges from 107.80×104 to 332.46×104 km2, with CLCD and MCD12Q1 having the highest area consistency. The spatial and sample consistency is highest in the regions of east-central Inner Mongolia, the Qinghai-Tibet Plateau and northern Xinjiang, while the distribution of southern grasslands is scattered and differs considerably among the ten products. MCD12Q1 is significantly more accurate than the other nine products, with an overall accuracy (OA) reaching 77.51% and a kappa coefficient of 0.51; CLCD is slightly less accurate than MCD12Q1 (OA=73.02%, kappa coefficient=0.45) and is more conducive to the fine monitoring and management of grassland because of its 30-meter resolution. The highest accuracy of grassland was found in the Inner Mongolia-Ningxia region and Qinghai-Tibet Plateau, while the accuracy was worst in the southeastern region. In the future grassland mapping, cartographers should improve the accuracy of the grassland distribution in South China and regions where grassland is confused with forest, cropland and bare land. We specify the availability of valuable data in existing land cover datasets for China's grasslands and call for researchers and the government to actively produce a new generation of grassland maps.
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Zhang Y, Zhang Q, Zhao Y, Deng Y, Zheng H. Urban spatial risk prediction and optimization analysis of POI based on deep learning from the perspective of an epidemic. INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION : ITC JOURNAL 2022; 112:102942. [PMID: 35945962 PMCID: PMC9353319 DOI: 10.1016/j.jag.2022.102942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/19/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
From an epidemiological perspective, previous research on COVID-19 has generally been based on classical statistical analyses. As a result, spatial information is often not used effectively. This paper uses image-based neural networks to explore the relationship between urban spatial risk and the distribution of infected populations, and the design of urban facilities. To achieve this objective, we use spatio-temporal data of people infected with new coronary pneumonia prior to 28 February 2020 in Wuhan. We then use kriging, which is a method of spatial interpolation, as well as core density estimation technology to establish the epidemic heat distribution on fine grid units. We further evaluate the influence of nine major spatial risk factors, including the distribution of agencies, hospitals, park squares, sports fields, banks and hotels, by testing them for significant positive correlation with the distribution of the epidemic. The weights of these spatial risk factors are used for training Generative Adversarial Network (GAN) models, which predict the distribution of cases in a given area. The input image for the machine learning model is a city plan converted by public infrastructures, and the output image is a map of urban spatial risk factors in the given area. The results of the trained model demonstrate that optimising the relevant point of interests (POI) in urban areas to effectively control potential risk factors can aid in managing the epidemic and preventing it from dispersing further.
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Affiliation(s)
- Yecheng Zhang
- College of Architecture & Art, Hefei University of Technology, Hefei, China
| | - Qimin Zhang
- School of Mechanical Engineering, Hefei University of Technology, Hefei, China
| | - Yuxuan Zhao
- College of Architecture & Art, Hefei University of Technology, Hefei, China
| | - Yunjie Deng
- College of Architecture & Art, Hefei University of Technology, Hefei, China
| | - Hao Zheng
- Stuart Weitzman School of Design, University of Pennsylvania, Philadelphia, United States
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Gong YF, Zhu LQ, Li YL, Zhang LJ, Xue JB, Xia S, Lv S, Xu J, Li SZ. Identification of the high-risk area for schistosomiasis transmission in China based on information value and machine learning: a newly data-driven modeling attempt. Infect Dis Poverty 2021; 10:88. [PMID: 34176515 PMCID: PMC8237418 DOI: 10.1186/s40249-021-00874-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/15/2021] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Schistosomiasis control is striving forward to transmission interruption and even elimination, evidence-lead control is of vital importance to eliminate the hidden dangers of schistosomiasis. This study attempts to identify high risk areas of schistosomiasis in China by using information value and machine learning. METHODS The local case distribution from schistosomiasis surveillance data in China between 2005 and 2019 was assessed based on 19 variables including climate, geography, and social economy. Seven models were built in three categories including information value (IV), three machine learning models [logistic regression (LR), random forest (RF), generalized boosted model (GBM)], and three coupled models (IV + LR, IV + RF, IV + GBM). Accuracy, area under the curve (AUC), and F1-score were used to evaluate the prediction performance of the models. The optimal model was selected to predict the risk distribution for schistosomiasis. RESULTS There is a more prone to schistosomiasis epidemic provided that paddy fields, grasslands, less than 2.5 km from the waterway, annual average temperature of 11.5-19.0 °C, annual average rainfall of 1000-1550 mm. IV + GBM had the highest prediction effect (accuracy = 0.878, AUC = 0.902, F1 = 0.920) compared with the other six models. The results of IV + GBM showed that the risk areas are mainly distributed in the coastal regions of the middle and lower reaches of the Yangtze River, the Poyang Lake region, and the Dongting Lake region. High-risk areas are primarily distributed in eastern Changde, western Yueyang, northeastern Yiyang, middle Changsha of Hunan province; southern Jiujiang, northern Nanchang, northeastern Shangrao, eastern Yichun in Jiangxi province; southern Jingzhou, southern Xiantao, middle Wuhan in Hubei province; southern Anqing, northwestern Guichi, eastern Wuhu in Anhui province; middle Meishan, northern Leshan, and the middle of Liangshan in Sichuan province. CONCLUSIONS The risk of schistosomiasis transmission in China still exists, with high-risk areas relatively concentrated in the coastal regions of the middle and lower reaches of the Yangtze River. Coupled models of IV and machine learning provide for effective analysis and prediction, forming a scientific basis for evidence-lead surveillance and control.
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Affiliation(s)
- Yan-Feng Gong
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Ling-Qian Zhu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Yin-Long Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Li-Juan Zhang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Jing-Bo Xue
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Shang Xia
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Shan Lv
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jing Xu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Shi-Zhu Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; HC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, 200025, China.
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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McMahon A, Mihretie A, Ahmed AA, Lake M, Awoke W, Wimberly MC. Remote sensing of environmental risk factors for malaria in different geographic contexts. Int J Health Geogr 2021; 20:28. [PMID: 34120599 PMCID: PMC8201719 DOI: 10.1186/s12942-021-00282-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/03/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Despite global intervention efforts, malaria remains a major public health concern in many parts of the world. Understanding geographic variation in malaria patterns and their environmental determinants can support targeting of malaria control and development of elimination strategies. METHODS We used remotely sensed environmental data to analyze the influences of environmental risk factors on malaria cases caused by Plasmodium falciparum and Plasmodium vivax from 2014 to 2017 in two geographic settings in Ethiopia. Geospatial datasets were derived from multiple sources and characterized climate, vegetation, land use, topography, and surface water. All data were summarized annually at the sub-district (kebele) level for each of the two study areas. We analyzed the associations between environmental data and malaria cases with Boosted Regression Tree (BRT) models. RESULTS We found considerable spatial variation in malaria occurrence. Spectral indices related to land cover greenness (NDVI) and moisture (NDWI) showed negative associations with malaria, as the highest malaria rates were found in landscapes with low vegetation cover and moisture during the months that follow the rainy season. Climatic factors, including precipitation and land surface temperature, had positive associations with malaria. Settlement structure also played an important role, with different effects in the two study areas. Variables related to surface water, such as irrigated agriculture, wetlands, seasonally flooded waterbodies, and height above nearest drainage did not have strong influences on malaria. CONCLUSION We found different relationships between malaria and environmental conditions in two geographically distinctive areas. These results emphasize that studies of malaria-environmental relationships and predictive models of malaria occurrence should be context specific to account for such differences.
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Affiliation(s)
- Andrea McMahon
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK USA
| | - Abere Mihretie
- Health, Development, and Anti-Malaria Association, Addis Ababa, Ethiopia
| | - Adem Agmas Ahmed
- Malaria Control and Elimination Partnership in Africa, Bahir Dar, Ethiopia
| | | | - Worku Awoke
- School of Public Health, Bahir Dar University, Bahir Dar, Ethiopia
| | - Michael Charles Wimberly
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK USA
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Rosas-Aguirre A, Moreno M, Moreno-Gutierrez D, Llanos-Cuentas A, Saavedra M, Contreras-Mancilla J, Barboza J, Alava F, Aguirre K, Carrasco G, Prussing C, Vinetz J, Conn JE, Speybroeck N, Gamboa D. Integrating Parasitological and Entomological Observations to Understand Malaria Transmission in Riverine Villages in the Peruvian Amazon. J Infect Dis 2021; 223:S99-S110. [PMID: 33906225 PMCID: PMC8079135 DOI: 10.1093/infdis/jiaa496] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Remote rural riverine villages account for most of the reported malaria cases in the Peruvian Amazon. As transmission decreases due to intensive standard control efforts, malaria strategies in these villages will need to be more focused and adapted to local epidemiology. METHODS By integrating parasitological, entomological, and environmental observations between January 2016 and June 2017, we provided an in-depth characterization of malaria transmission dynamics in 4 riverine villages of the Mazan district, Loreto department. RESULTS Despite variation across villages, malaria prevalence by polymerase chain reaction in March 2016 was high (>25% in 3 villages), caused by Plasmodium vivax mainly and composed of mostly submicroscopic infections. Housing without complete walls was the main malaria risk factor, while households close to forest edges were more commonly identified as spatial clusters of malaria prevalence. Villages in the basin of the Mazan River had a higher density of adult Anopheles darlingi mosquitoes, and retained higher prevalence and incidence rates compared to villages in the basin of the Napo River despite test-and-treat interventions. CONCLUSIONS High heterogeneity in malaria transmission was found across and within riverine villages, resulting from interactions between the microgeographic landscape driving diverse conditions for vector development, housing structure, and human behavior.
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Affiliation(s)
- Angel Rosas-Aguirre
- Research Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium.,Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marta Moreno
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Diamantina Moreno-Gutierrez
- Research Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium.,Facultad de Medicina Humana, Universidad Nacional de la Amazonía Peruana, Loreto, Peru
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Marlon Saavedra
- International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Juan Contreras-Mancilla
- International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jose Barboza
- International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Freddy Alava
- International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Kristhian Aguirre
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Gabriel Carrasco
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.,Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Catharine Prussing
- School of Public Health, Department of Biomedical Sciences, State University of New York, Albany, New York, USA.,Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Joseph Vinetz
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.,Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Jan E Conn
- School of Public Health, Department of Biomedical Sciences, State University of New York, Albany, New York, USA.,Wadsworth Center, New York State Department of Health, Albany, New York, USA
| | - Niko Speybroeck
- Research Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium
| | - Dionicia Gamboa
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.,International Centers of Excellence for Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
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11
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Progress towards onchocerciasis elimination in Côte d'Ivoire: A geospatial modelling study. PLoS Negl Trop Dis 2021; 15:e0009091. [PMID: 33566805 PMCID: PMC7875389 DOI: 10.1371/journal.pntd.0009091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 01/01/2021] [Indexed: 11/19/2022] Open
Abstract
Background Côte d’Ivoire has had 45 years of intervention for onchocerciasis by vector control (from 1975 to 1991), ivermectin mass drug administration (MDA) (from 1992 to 1994) and community directed treatment with ivermectin (CDTi) from 1995 to the present. We modeled onchocerciasis endemicity during two time periods that correspond to the scale up of vector control and ivermectin distribution, respectively. This analysis illustrates progress towards elimination during these periods, and it has identified potential hotspots areas that are at risk for ongoing transmission. Methods and findings The analysis used Ministry of Health skin snip microfilaria (MF) prevalence and intensity data collected between 1975 and 2016. Socio-demographic and environmental factors were incorporated into a predictive, machine learning algorithm to create continuous maps of onchocerciasis endemicity. Overall predicted mean MF prevalence decreased from 51.8% circa 1991 to 3.9% circa 2016. The model predicted infection foci with higher prevalence in the southern region of the country. Predicted mean community MF load (CMFL) decreased from 10.1MF/snip circa 1991 to 0.1MF/snip circa 2016. Again, the model predicts foci with higher Mf densities in the southern region. For assessing model performance, the root mean squared error and R2 values were 1.14 and 0.62 respectively for a model trained with data collected prior to 1991, and 1.28 and 0.57 for the model trained with infection survey data collected later, after the introduction of ivermectin. Finally, our models show that proximity to permanent inland bodies of water and altitude were the most informative variables that correlated with onchocerciasis endemicity. Conclusion/Significance This study further documents the significant reduction of onchocerciasis infection following widespread use of ivermectin for onchocerciasis control in Côte d’Ivoire. Maps produced predict areas at risk for ongoing infection and transmission. Onchocerciasis might be eliminated in Côte d’Ivoire in the future with a combination of sustained CDTi with high coverage, active surveillance, and close monitoring for persistent infection in previously hyper-endemic areas. Côte d’Ivoire is endemic for onchocerciasis (also known as “river blindness”). This neglected tropical disease is transmitted by biting black flies that breed in fast flowing rivers. From 1975 to 1991, onchocerciasis control was based on weekly aerial spraying of the insecticide temephos, on black fly breeding sites. Vector control, however, was mostly focused on the northern and central parts of the country. From 1992 to present, mass treatment with ivermectin was implemented in all endemic areas, including forested regions in the south. Here we present the first geospatial estimates of onchocerciasis endemicity over time. Using the machine learning algorithm quantile regression forest, we implemented models to: identify important socio-demographic and environmental factors that correlate with onchocerciasis infection; predict the prevalence and density of infection in areas without ground-truth data; delineate remaining infection hotspots. Our results show that Côte d’Ivoire has made very significant progress in reducing infection parameters over time, and they may help to inform future interventions to achieve the goal of onchocerciasis elimination in Côte d’Ivoire.
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12
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Zhou G, Zhong D, Lee MC, Wang X, Atieli HE, Githure JI, Githeko AK, Kazura J, Yan G. Multi-Indicator and Multistep Assessment of Malaria Transmission Risks in Western Kenya. Am J Trop Med Hyg 2021; 104:1359-1370. [PMID: 33556042 DOI: 10.4269/ajtmh.20-1211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 12/24/2020] [Indexed: 11/07/2022] Open
Abstract
Malaria risk factor assessment is a critical step in determining cost-effective intervention strategies and operational plans in a regional setting. We develop a multi-indicator multistep approach to model the malaria risks at the population level in western Kenya. We used a combination of cross-sectional seasonal malaria infection prevalence, vector density, and cohort surveillance of malaria incidence at the village level to classify villages into malaria risk groups through unsupervised classification. Generalized boosted multinomial logistics regression analysis was performed to determine village-level risk factors using environmental, biological, socioeconomic, and climatic features. Thirty-six villages in western Kenya were first classified into two to five operational groups based on different combinations of malaria risk indicators. Risk assessment indicated that altitude accounted for 45-65% of all importance value relative to all other factors; all other variable importance values were < 6% in all models. After adjusting by altitude, villages were classified into three groups within distinct geographic areas regardless of the combination of risk indicators. Risk analysis based on altitude-adjusted classification indicated that factors related to larval habitat abundance accounted for 63% of all importance value, followed by geographic features related to the ponding effect (17%), vegetation cover or greenness (15%), and the number of bed nets combined with February temperature (5%). These results suggest that altitude is the intrinsic factor in determining malaria transmission risk in western Kenya. Malaria vector larval habitat management, such as habitat reduction and larviciding, may be an important supplement to the current first-line vector control tools in the study area.
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Affiliation(s)
- Guofa Zhou
- 1Program in Public Health, University of California, Irvine, California
| | - Daibin Zhong
- 1Program in Public Health, University of California, Irvine, California
| | - Ming-Chieh Lee
- 1Program in Public Health, University of California, Irvine, California
| | - Xiaoming Wang
- 1Program in Public Health, University of California, Irvine, California
| | - Harrysone E Atieli
- 2School of Public Health and Community Development, Maseno University, Kisumu, Kenya
| | - John I Githure
- 3International Center of Excellence in Malaria Research, Tom Mboya University College, Homabay, Kenya
| | - Andrew K Githeko
- 4Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James Kazura
- 5Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Guiyun Yan
- 1Program in Public Health, University of California, Irvine, California
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13
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DePina AJ, Stresman G, Barros HSB, Moreira AL, Dia AK, Furtado UD, Faye O, Seck I, Niang EHA. Updates on malaria epidemiology and profile in Cabo Verde from 2010 to 2019: the goal of elimination. Malar J 2020; 19:380. [PMID: 33097051 PMCID: PMC7585190 DOI: 10.1186/s12936-020-03455-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/18/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Located in West Africa, Cabo Verde is an archipelago consisting of nine inhabited islands. Malaria has been endemic since the settlement of the islands during the sixteenth century and is poised to achieve malaria elimination in January 2021. The aim of this research is to characterize the trends in malaria cases from 2010 to 2019 in Cabo Verde as the country transitions from endemic transmission to elimination and prevention of reintroduction phases. METHODS All confirmed malaria cases reported to the Ministry of Health between 2010 and 2019 were extracted from the passive malaria surveillance system. Individual-level data available included age, gender, municipality of residence, and the self-reported countries visited if travelled within the past 30 days, therby classified as imported. Trends in reported cases were visualized and multivariable logistic regression used to assess risk factors associated with a malaria case being imported and differences over time. RESULTS A total of 814 incident malaria cases were reported in the country between 2010 and 2019, the majority of which were Plasmodium falciparum. Overall, prior to 2017, when the epidemic occurred, 58.1% (95% CI 53.6-64.6) of infections were classified as imported, whereas during the post-epidemic period, 93.3% (95% CI 86.9-99.7) were imported. The last locally acquired case was reported in January 2018. Imported malaria cases were more likely to be 25-40 years old (AOR: 15.1, 95% CI 5.9-39.2) compared to those under 15 years of age and more likely during the post-epidemic period (AOR: 56.1; 95% CI 13.9-225.5) and most likely to be reported on Sao Vicente Island (AOR = 4256.9, 95% CI = 260-6.9e+4) compared to Boavista. CONCLUSIONS Cabo Verde has made substantial gains in reducing malaria burden in the country over the past decade and are poised to achieve elimination in 2021. However, the high mobility between the islands and continental Africa, where malaria is still highly endemic, means there is a constant risk of malaria reintroduction. Characterization of imported cases provides useful insight for programme and enables better evidence-based decision-making to ensure malaria elimination can be sustained.
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Affiliation(s)
- Adilson José DePina
- Programa de Eliminação do Paludismo, CCS-SIDA, Ministério da Saúde e da Segurança Social, Praia, Cabo Verde.
- Ecole Doctorale des Sciences de la Vie, de la Santé et de l'Environnement (ED-SEV), Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal.
| | - Gillian Stresman
- Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | | | - António Lima Moreira
- Programa Nacional de Luta contra as Doenças de Transmissão vectorial e Problemas de Saúde Associadas ao Meio Ambiente, Ministério da Saúde e da Segurança Social, Praia, Cabo Verde
| | - Abdoulaye Kane Dia
- Ecole Doctorale des Sciences de la Vie, de la Santé et de l'Environnement (ED-SEV), Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal
- Laboratoire d'Ecologie Vectorielle et Parasitaire,Faculté des Sciences et Techniques, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal
| | | | - Ousmane Faye
- Laboratoire d'Ecologie Vectorielle et Parasitaire,Faculté des Sciences et Techniques, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal
| | - Ibrahima Seck
- Institut de Santé et Développement, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal
| | - El Hadji Amadou Niang
- Laboratoire d'Ecologie Vectorielle et Parasitaire,Faculté des Sciences et Techniques, Université Cheikh Anta Diop (UCAD) de Dakar, Dakar, Sénégal
- Aix Marseille Univ, IRD, AP-HM, MEPHI, IHU-Méditerranée Infection, Marseille, France
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14
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Rocha EM, Katak RDM, Campos de Oliveira J, Araujo MDS, Carlos BC, Galizi R, Tripet F, Marinotti O, Souza-Neto JA. Vector-Focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies. Trop Med Infect Dis 2020; 5:E161. [PMID: 33092228 PMCID: PMC7709627 DOI: 10.3390/tropicalmed5040161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/05/2023] Open
Abstract
In Brazil, malaria transmission is mostly confined to the Amazon, where substantial progress has been made towards disease control in the past decade. Vector control has been historically considered a fundamental part of the main malaria control programs implemented in Brazil. However, the conventional vector-control tools have been insufficient to control or eliminate local vector populations due to the complexity of the Amazonian rainforest environment and ecological features of malaria vector species in the Amazon, especially Anopheles darlingi. Malaria elimination in Brazil and worldwide eradication will require a combination of conventional and new approaches that takes into account the regional specificities of vector populations and malaria transmission dynamics. Here we present an overview on both conventional and novel promising vector-focused tools to curb malaria transmission in the Brazilian Amazon. If well designed and employed, vector-based approaches may improve the implementation of malaria-control programs, particularly in remote or difficult-to-access areas and in regions where existing interventions have been unable to eliminate disease transmission. However, much effort still has to be put into research expanding the knowledge of neotropical malaria vectors to set the steppingstones for the optimization of conventional and development of innovative vector-control tools.
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Affiliation(s)
- Elerson Matos Rocha
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Ricardo de Melo Katak
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Juan Campos de Oliveira
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Maisa da Silva Araujo
- Laboratory of Medical Entomology, Oswaldo Cruz Foundation, FIOCRUZ RONDONIA, Porto Velho, RO 76812-245, Brazil;
| | - Bianca Cechetto Carlos
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
| | - Roberto Galizi
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | - Frederic Tripet
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | | | - Jayme A. Souza-Neto
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
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15
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Rosas-Aguirre A, Guzman-Guzman M, Chuquiyauri R, Moreno M, Manrique P, Ramirez R, Carrasco-Escobar G, Rodriguez H, Speybroeck N, Conn JE, Gamboa D, Vinetz JM, Llanos-Cuentas A. Temporal and Microspatial Heterogeneity in Transmission Dynamics of Coendemic Plasmodium vivax and Plasmodium falciparum in Two Rural Cohort Populations in the Peruvian Amazon. J Infect Dis 2020; 223:1466-1477. [PMID: 32822474 DOI: 10.1093/infdis/jiaa526] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/17/2020] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Malaria is highly heterogeneous: its changing malaria microepidemiology needs to be addressed to support malaria elimination efforts at the regional level. METHODS A 3-year, population-based cohort study in 2 settings in the Peruvian Amazon (Lupuna, Cahuide) followed participants by passive and active case detection from January 2013 to December 2015. Incidence and prevalence rates were estimated using microscopy and polymerase chain reaction (PCR). RESULTS Lupuna registered 1828 infections (1708 Plasmodium vivax, 120 Plasmodium falciparum; incidence was 80.7 infections/100 person-years (95% confidence interval [CI] , 77.1-84.5). Cahuide detected 1046 infections (1024 P vivax, 20 P falciparum, 2 mixed); incidence was 40.2 infections/100 person-years (95% CI, 37.9-42.7). Recurrent P vivax infections predominated onwards from 2013. According to PCR data, submicroscopic predominated over microscopic infections, especially in periods of low transmission. The integration of parasitological, entomological, and environmental observations evidenced an intense and seasonal transmission resilient to standard control measures in Lupuna and a persistent residual transmission after severe outbreaks were intensively handled in Cahuide. CONCLUSIONS In 2 exemplars of complex local malaria transmission, standard control strategies failed to eliminate submicroscopic and hypnozoite reservoirs, enabling persistent transmission.
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Affiliation(s)
- Angel Rosas-Aguirre
- Research Institute of Health and Society, Université Catholique de Louvain, Brussels, Belgium.,Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Mitchel Guzman-Guzman
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Raul Chuquiyauri
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Marta Moreno
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA.,London School of Hygiene and Tropical Medicine, Department of Immunology and Infection, London, United Kingdom
| | - Paulo Manrique
- Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Roberson Ramirez
- Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Gabriel Carrasco-Escobar
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.,Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Hugo Rodriguez
- Dirección Regional de Salud Loreto DIRESA Loreto, Loreto, Perú
| | - Niko Speybroeck
- Research Institute of Health and Society, Université Catholique de Louvain, Brussels, Belgium
| | - Jan E Conn
- Wadsworth Center, New York State Department of Health, Albany, New York, USA.,Department of Biomedical Sciences, School of Public Health, University at Albany, State University of New York, Albany, New York, USA
| | - Dionicia Gamboa
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Joseph M Vinetz
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Laboratorio International Centers of Excellence in Malaria Research-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.,Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Perú.,Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Perú
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16
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Zhao X, Thanapongtharm W, Lawawirojwong S, Wei C, Tang Y, Zhou Y, Sun X, Cui L, Sattabongkot J, Kaewkungwal J. Malaria Risk Map Using Spatial Multi-Criteria Decision Analysis along Yunnan Border During the Pre-elimination Period. Am J Trop Med Hyg 2020; 103:793-809. [PMID: 32602435 PMCID: PMC7410425 DOI: 10.4269/ajtmh.19-0854] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In moving toward malaria elimination, finer scale malaria risk maps are required to identify hotspots for implementing surveillance–response activities, allocating resources, and preparing health facilities based on the needs and necessities at each specific area. This study aimed to demonstrate the use of multi-criteria decision analysis (MCDA) in conjunction with geographic information systems (GISs) to create a spatial model and risk maps by integrating satellite remote-sensing and malaria surveillance data from 18 counties of Yunnan Province along the China–Myanmar border. The MCDA composite and annual models and risk maps were created from the consensus among the experts who have been working and know situations in the study areas. The experts identified and provided relative factor weights for nine socioeconomic and disease ecology factors as a weighted linear combination model of the following: ([Forest coverage × 0.041] + [Cropland × 0.086] + [Water body × 0.175] + [Elevation × 0.297] + [Human population density × 0.043] + [Imported case × 0.258] + [Distance to road × 0.030] + [Distance to health facility × 0.033] + [Urbanization × 0.036]). The expert-based model had a good prediction capacity with a high area under curve. The study has demonstrated the novel integrated use of spatial MCDA which combines multiple environmental factors in estimating disease risk by using decision rules derived from existing knowledge or hypothesized understanding of the risk factors via diverse quantitative and qualitative criteria using both data-driven and qualitative indicators from the experts. The model and fine MCDA risk map developed in this study could assist in focusing the elimination efforts in the specifically identified locations with high risks.
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Affiliation(s)
- Xiaotao Zhao
- Yunnan Institute of Parasitic Diseases, Pu'er, P. R. China.,Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Weerapong Thanapongtharm
- Department of Livestock Development, Veterinary Epidemiological Center, Bureau of Disease Control and Veterinary Services, Bangkok, Thailand
| | - Siam Lawawirojwong
- Geo-Informatics and Space Technology Development Agency, Bangkok, Thailand
| | - Chun Wei
- Yunnan Institute of Parasitic Diseases, Pu'er, P. R. China
| | - Yerong Tang
- Yunnan Institute of Parasitic Diseases, Pu'er, P. R. China
| | - Yaowu Zhou
- Yunnan Institute of Parasitic Diseases, Pu'er, P. R. China
| | - Xiaodong Sun
- Yunnan Institute of Parasitic Diseases, Pu'er, P. R. China
| | - Liwang Cui
- Division of Infectious Diseases and Internal Medicine, Department of Internal Medicine, University of South Florida, Tampa, Florida
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Jaranit Kaewkungwal
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Center of Excellence for Biomedical and Public Health Informatics (BIOPHICS), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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17
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Moreno-Gutierrez D, Rosas-Aguirre A, Llanos-Cuentas A, Bilcke J, Barboza JL, Hayette MP, Contreras-Mancilla J, Aguirre K, Gamboa D, Rodriguez H, Speybroeck N, Beutels P. Economic costs analysis of uncomplicated malaria case management in the Peruvian Amazon. Malar J 2020; 19:161. [PMID: 32316981 PMCID: PMC7175533 DOI: 10.1186/s12936-020-03233-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 04/10/2020] [Indexed: 02/08/2023] Open
Abstract
Background Case management is one of the principal strategies for malaria control. This study aimed to estimate the economic costs of uncomplicated malaria case management and explore the influence of health-seeking behaviours on those costs. Methods A knowledge, attitudes and practices (KAP) survey was applied to 680 households of fifteen communities in Mazan-Loreto in March 2017, then a socio-economic survey was conducted in September 2017 among 161 individuals with confirmed uncomplicated malaria in the past 3 months. Total costs per episode were estimated from both provider (Ministry of Health, MoH) and patient perspectives. Direct costs were estimated using a standard costing estimation procedure, while the indirect costs considered the loss of incomes among patients, substitute labourers and companions due to illness in terms of the monthly minimum wage. Sensitivity analysis evaluated the uncertainty of the average cost per episode. Results The KAP survey showed that most individuals (79.3%) that had malaria went to a health facility for a diagnosis and treatment, 2.7% received those services from community health workers, and 8% went to a drugstore or were self-treated at home. The average total cost per episode in the Mazan district was US$ 161. The cost from the provider’s perspective was US$ 30.85 per episode while from the patient’s perspective the estimated cost was US$ 131 per episode. The average costs per Plasmodium falciparum episode (US$ 180) were higher than those per Plasmodium vivax episode (US$ 156) due to longer time lost from work by patients with P. falciparum infections (22.2 days) than by patients with P. vivax infections (17.0 days). The delayed malaria diagnosis (after 48 h of the onset of symptoms) was associated with the time lost from work due to illness (adjusted mean ratio 1.8; 95% CI 1.3, 2.6). The average cost per malaria episode was most sensitive to the uncertainty around the lost productivity cost due to malaria. Conclusions Despite the provision of free malaria case management by MoH, there is delay in seeking care and the costs of uncomplicated malaria are mainly borne by the families. These costs are not well perceived by the society and the substantial financial impact of the disease can be frequently undervalued in public policy planning.
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Affiliation(s)
- Diamantina Moreno-Gutierrez
- Facultad de Medicina Humana, Universidad Nacional de la Amazonía Peruana, Iquitos, Loreto, 160, Peru. .,Research Institute of Health and Society (IRSS), Université Catholique de Louvain, 1200, Brussels, Belgium. .,Centre for Health Economics Research and Modelling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, 2000, Antwerp, Belgium.
| | - Angel Rosas-Aguirre
- Research Institute of Health and Society (IRSS), Université Catholique de Louvain, 1200, Brussels, Belgium.,Fund for Scientific Research FNRS, 1000, Brussels, Belgium.,Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru.,Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Joke Bilcke
- Centre for Health Economics Research and Modelling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, 2000, Antwerp, Belgium
| | - José Luis Barboza
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Marie-Pierre Hayette
- Department of Clinical Microbiology, Center for Interdisciplinary Research on Medicines (CIRM), University Hospital of Liège, 4000, Liège, Belgium
| | - Juan Contreras-Mancilla
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru.,Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Kristhian Aguirre
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Dionicia Gamboa
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, 31, Peru.,Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, 31, Peru.,Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, 31, Peru
| | - Hugo Rodriguez
- Facultad de Medicina Humana, Universidad Nacional de la Amazonía Peruana, Iquitos, Loreto, 160, Peru
| | - Niko Speybroeck
- Research Institute of Health and Society (IRSS), Université Catholique de Louvain, 1200, Brussels, Belgium
| | - Philippe Beutels
- Centre for Health Economics Research and Modelling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, 2000, Antwerp, Belgium
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Ecological Risk Assessment and Impact Factor Analysis of Alpine Wetland Ecosystem Based on LUCC and Boosted Regression Tree on the Zoige Plateau, China. REMOTE SENSING 2020. [DOI: 10.3390/rs12030368] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Zoige Plateau is typical of alpine wetland ecosystems worldwide, which play a key role in regulating global climate and ecological balance. Due to the influence of global climate change and intense human activities, the stability and sustainability of the ecosystems associated with the alpine marsh wetlands are facing enormous threats. It is important to establish a precise risk assessment method to evaluate the risks to alpine wetlands ecosystems, and then to understand the influencing factors of ecological risk. However, the multi-index evaluation method of ecological risk in the Zoige region is overly focused on marsh wetlands, and the smallest units of assessment are relatively large. Although recently developed landscape ecological risk assessment (ERA) methods can address the above limitations, the final directionality of the evaluation results is not clear. In this work, we used the landscape ERA method based on land use and land cover changes (LUCC) to evaluate the ecological risks to an alpine wetland ecosystem from a spatial pixel scale (5 km × 5 km). Furthermore, the boosted regression tree (BRT) model was adopted to quantitatively analyze the impact factors of ecological risk. The results show the following: (1) From 1990 to 2016, the land use and land cover (LULC) types in the study area changed markedly. In particular, the deep marshes and aeolian sediments, and whereas construction land areas changed dramatically, the alpine grassland changed relatively slowly. (2) The ecological risk in the study area increased and was dominated by regions with higher and moderate risk levels. Meanwhile, these areas showed notable spatio-temporal changes, significant spatial correlation, and a high degree of spatial aggregation. (3) The topographic distribution, climate changes and human activities influenced the stability of the study area. Elevation (23.4%) was the most important factor for ecological risk, followed by temperature (16.2%). Precipitation and GDP were also seen to be adverse factors affecting ecological risk, at levels of 13.0% and 12.1%, respectively. The aim of this study was to provide more precise and specific support for defining conservation objectives, and ecological management in alpine wetland ecosystems.
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