INTRODUCTION: Understanding human mobility's role in malaria transmission is critical to successful control and elimination. However, common approaches to measuring mobility are ill-equipped for remote regions such as the Amazon. This study develops a network survey to quantify the effect of community connectivity and mobility on malaria transmission. METHODS: We measure community connectivity across the study area using a respondent driven sampling design among key informants who are at least 18 years of age. 45 initial communities will be selected: 10 in Brazil, 10 in Ecuador and 25 in Peru. Participants will be recruited in each initial node and administered a survey to obtain data on each community's mobility patterns. Survey responses will be ranked and the 2-3 most connected communities will then be selected and surveyed. This process will be repeated for a third round of data collection. Community network matrices will be linked with each country's malaria surveillance system to test the effects of mobility on disease risk. ETHICS AND DISSEMINATION: This study protocol has been approved by the institutional review boards of Duke University (USA), Universidad San Francisco de Quito (Ecuador), Universidad Peruana Cayetano Heredia (Peru) and Universidade Federal Minas Gerais (Brazil). Results will be disseminated in communities by the end of the study.
Community Networks , Malaria , Humans , Peru/epidemiology , Ecuador/epidemiology , Brazil/epidemiology , Malaria/epidemiology , Malaria/prevention & control
Objectives: Understanding human mobility's role on malaria transmission is critical to successful control and elimination. However, common approaches to measuring mobility are ill-equipped for remote regions such as the Amazon. This study develops a network survey to quantify the effect of community connectivity and mobility on malaria transmission. Design: A community-level network survey. Setting: We collect data on community connectivity along three river systems in the Amazon basin: the Pastaza river corridor spanning the Ecuador-Peru border; and the Amazon and Javari river corridors spanning the Brazil-Peru border. Participants: We interviewed key informants in Brazil, Ecuador, and Peru, including from indigenous communities: Shuar, Achuar, Shiwiar, Kichwa, Ticuna, and Yagua. Key informants are at least 18 years of age and are considered community leaders. Primary outcome: Weekly, community-level malaria incidence during the study period. Methods: We measure community connectivity across the study area using a respondent driven sampling design. Forty-five communities were initially selected: 10 in Brazil, 10 in Ecuador, and 25 in Peru. Participants were recruited in each initial node and administered a survey to obtain data on each community's mobility patterns. Survey responses were ranked and the 2-3 most connected communities were then selected and surveyed. This process was repeated for a third round of data collection. Community network matrices will be linked with eadch country's malaria surveillance system to test the effects of mobility on disease risk. Findings: To date, 586 key informants were surveyed from 126 communities along the Pastaza river corridor. Data collection along the Amazon and Javari river corridors is ongoing. Initial results indicate that network sampling is a superior method to delineate migration flows between communities. Conclusions: Our study provides measures of mobility and connectivity in rural settings where traditional approaches are insufficient, and will allow us to understand mobility's effect on malaria transmission.
BACKGROUND: The Amazon environment has been exposed in the last decades to radical changes that have been accompanied by a remarkable rise of both Plasmodium falciparum and Plasmodium vivax malaria. The malaria transmission process is highly influenced by factors such as spatial and temporal heterogeneities of the environment and individual-based characteristics of mosquitoes and humans populations. All these determinant factors can be simulated effectively trough agent-based models. METHODS: This paper presents a validated agent-based model of local-scale malaria transmission. The model reproduces the environment of a typical riverine village in the northern Peruvian Amazon, where the malaria transmission is highly seasonal and apparently associated with flooding of large areas caused by the neighbouring river. Agents representing humans, mosquitoes and the two species of Plasmodium (P. falciparum and P. vivax) are simulated in a spatially explicit representation of the environment around the village. The model environment includes: climate, people houses positions and elevation. A representation of changes in the mosquito breeding areas extension caused by the river flooding is also included in the simulation environment. RESULTS: A calibration process was carried out to reproduce the variations of the malaria monthly incidence over a period of 3 years. The calibrated model is also able to reproduce the spatial heterogeneities of local scale malaria transmission. A "what if" eradication strategy scenario is proposed: if the mosquito breeding sites are eliminated through mosquito larva habitat management in a buffer area extended at least 200 m around the village, the malaria transmission is eradicated from the village. CONCLUSIONS: The use of agent-based models can reproduce effectively the spatiotemporal variations of the malaria transmission in a low endemicity environment dominated by river floodings like in the Amazon.
Malaria, Falciparum/epidemiology , Malaria, Vivax/epidemiology , Topography, Medical , Animals , Computer Simulation , Culicidae , Disease Transmission, Infectious , Humans , Incidence , Malaria, Falciparum/transmission , Malaria, Vivax/transmission , Models, Statistical , Rainforest , Spatio-Temporal Analysis , Tropical Climate
Climate change will exacerbate the vulnerability of places and people around the world in the next decades, especially in less developed regions. In this paper, we investigate future scenarios of population vulnerability to climate change for the next 30 years in 66 regions of the state of Minas Gerais, Brazil. Based upon the Alkire & Foster Index, we integrate simulated and projected dimensions of population vulnerability into a Multidimensional Index, showing how scenarios of temperature change would affect each region's relative vulnerability in the future. Results suggest that economic and health dimensions are the highest contributors to increases in temperature-related vulnerability, with the poorest and agribusiness regions being the most impacted in decades to come...
As mudanças climáticas exacerbarão, nas próximas décadas, a vulnerabilidade de populações, lugares e pessoas ao redor do mundo, especialmente nos países em desenvolvimento. Este artigo investiga cenários hipotéticos futuros de vulnerabilidade às mudanças climáticas para os próximos 30 anos, em 66 microrregiões do Estado de Minas Gerais. Com base no Índice de Alkire e Foster, são integradas as dimensões simuladas e projetadas de vulnerabilidade populacional em um indicador multidimensional, o qual mostra como cenários de mudanças de temperatura afetariam a vulnerabilidade relativa de cada região no futuro. Os resultados sugerem que as dimensões econômica e de saúde são as maiores contribuintes para o aumento da vulnerabilidade relacionada às alterações na temperatura média, com as regiões mais pobres e voltadas ao agronegócio constituindo as mais afetadas em cenários futuros...
En las próximas décadas, el cambio climático exacerbará la vulnerabilidad de las poblaciones alrededor del mundo, especialmente en los países en desarrollo. En este artículo se investigan escenarios hipotéticos futuros de vulnerabilidad frente al cambio climático para los próximos 30 años en 66 microrregiones del estado de Minas Gerais. Sobre la base del Índice de Alkire y Foster, se integran en un indicador multidimensional las dimensiones simuladas y proyectadas de vulnerabilidad poblacional, mostrando cómo los escenarios de cambios de temperatura afectarían la vulnerabilidad relativa de cada región en el futuro. Los resultados sugieren que las dimensiones económica y de salud son las que más contribuyen en el aumento de la vulnerabilidad relacionada con las alteraciones de la temperatura media, y que las regiones más pobres y volcadas al agronegocio constituirán las más afectadas en estos escenarios futuros...
Humans , Climate Change , Population Dynamics , Environment , Brazil , Demography , Social Vulnerability
Rural settlement in previously sparsely occupied areas of the Brazilian Amazon has been associated with high levels of forest loss and unclear long-term social outcomes. We focus here on the micro-level processes in one settlement area to answer the question of how settler and farm endowments affect household poverty. We analyze the extent to which poverty is sensitive to changes in natural capital, land use strategies, and biophysical characteristics of properties (particularly soil quality). Cumulative time spent in poverty is simulated using Markovian processes, which show that accessibility to markets and land use system are especially important for decreasing poverty among households in our sample. Wealtheir households are selected into commercial production of perennials before our initial observation, and are therefore in poverty a lower proportion of the time. Land in pasture, in contrast, has an independent effect on reducing the proportion of time spent in poverty. Taken together, these results show that investments in roads and the institutional structures needed to make commercial agriculture or ranching viable in existing and new settlement areas can improve human well-being in frontiers.
Agriculture , Economic Development , Environment , Family Characteristics , Ownership , Poverty , Rural Population , Animal Husbandry , Brazil , Commerce , Conservation of Natural Resources , Ecosystem , Humans , Income , Natural Resources , Rivers , Social Class , Soil , Transportation
One of Daniel Hogan's lasting impacts on international demography community comes through his advocacy for studying bidirectional relationships between environment and demography, particularly migration. We build on his holistic approach to mobility and examine dynamic changes in land use and migration among small farm families in Altamira, Pará, Brazil. We find that prior area in either pasture or perennials promotes out-migration of adult children, but that out-migration is not directly associated with land-use change. In contrast to early formulations of household life cycle models that argued that aging parents would decrease productive land use as children left the farm, we find no effect of out-migration of adult children on land-use change. Instead, remittances facilitate increases in area in perennials, a slower to pay off investment that requires scarce capital, but in pasture. While remittances are rare, they appear to permit sound investments in the rural milieu and thus to slow rural exodus and the potential consolidation of land into large holdings. We would do well to promote the conditions that allow them to be sent and to be used productively to keep families on the land to avoid the specter of extensive deforestation for pasture followed by land consolidation.
This paper analyses poverty and inequality dynamics among smallholders along the Transamazon High-way. We measure changes in poverty and inequality for original settlers and new owners, contrasting income-based with multidimensional indices of well-being. Our results show an overall reduction in both poverty and inequality among smallholders, although poverty decline was more pronounced among new owners, while inequality reduction was larger among original settlers. This trend suggests that families have an initial improvement in livelihood and well-being which tends to reach a limit later-a sign of structural limitations common to rural areas and maybe a replication of boom and bust trends in local economies among Amazonian municipalities. In addition, our multidimensional estimates of well-being reveal that some economically viable land use strategies of smallholders (e.g., pasture) may have important ecological implications for the regional landscape. These findings highlight the public policy challenges for fostering sustainable development among rural populations.
