Agricultural Colonization and Malaria on the Amazon Frontier

Singer, Burton H.; Castro, Márcia C.

doi:10.1111/j.1749-6632.2001.tb02753.x

Cited by 70 publications

(79 citation statements)

References 29 publications

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“…The legacy of frontier cultivation in Taiwan may, therefore, be increased risk of scrub typhus infection. The association of frontier colonization with outbreaks of scrub typhus has also been documented in several other countries (Traub and Wisseman, 1974), although our study is the first one to quantitatively investigate such an association, suggesting that, similar to other vector-borne diseases, land use policy that encourages agricultural practices in the frontiers should also contemplate the potential for elevated burdens of scrub typhus infection and other vector-borne diseases (Walsh et al, 1993;Singer and de Castro 2001).…”

Section: Discussionmentioning

confidence: 90%

Bayesian spatial modelling and the significance of agricultural land use to scrub typhus infection in Taiwan

Wardrop

Kuo

Wang³

et al. 2013

Geospat Health

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Abstract. Scrub typhus is transmitted by the larval stage of trombiculid mites. Environmental factors, including land cover and land use, are known to influence breeding and survival of trombiculid mites and, thus, also the spatial heterogeneity of scrub typhus risk. Here, a spatially autoregressive modelling framework was applied to scrub typhus incidence data from Taiwan, covering the period 2003 to 2011, to provide increased understanding of the spatial pattern of scrub typhus risk and the environmental and socioeconomic factors contributing to this pattern. A clear spatial pattern in scrub typhus incidence was observed within Taiwan, and incidence was found to be significantly correlated with several land cover classes, temperature, elevation, normalized difference vegetation index, rainfall, population density, average income and the proportion of the population that work in agriculture. The final multivariate regression model included statistically significant correlations between scrub typhus incidence and average income (negatively correlated), the proportion of land that contained mosaics of cropland and vegetation (positively correlated) and elevation (positively correlated). These results highlight the importance of land cover on scrub typhus incidence: mosaics of cropland and vegetation represent a transitional land cover type which can provide favourable habitats for rodents and, therefore, trombiculid mites. In Taiwan, these transitional land cover areas tend to occur in less populated and mountainous areas, following the frontier establishment and subsequent partial abandonment of agricultural cultivation, due to demographic and socioeconomic changes. Future land use policy decision-making should ensure that potential public health outcomes, such as modified risk of scrub typhus, are considered.

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Section: Discussionmentioning

confidence: 90%

Bayesian spatial modelling and the significance of agricultural land use to scrub typhus infection in Taiwan

Wardrop

Kuo

Wang³

et al. 2013

Geospat Health

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“…By using a local indicator of spatial association, G* i (d) statistic (38)(39)(40)(41), clusters of high and low malaria rates were identified for all survey years. Rates were interpolated for ''unoccupied'' plots by using kriging estimators (42)(43)(44). The interpolated rates combined with the cluster analysis facilitated the definition of distinctive subareas (in terms of malaria risk) within Machadinho (Fig.…”

Section: Methodsmentioning

confidence: 99%

Malaria risk on the Amazon frontier

Castro

Monte-Mór

Sawyer

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

212

237

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Frontier malaria is a biological, ecological, and sociodemographic phenomenon operating over time at three spatial scales (micro͞ individual, community, and state and national). We explicate these linkages by integrating data from remote sensing surveys, groundlevel surveys and ethnographic appraisal, focusing on the Machadinho settlement project in Rondô nia, Brazil. Spatially explicit analyses reveal that the early stages of frontier settlement are dominated by environmental risks, consequential to ecosystem transformations that promote larval habitats of Anopheles darlingi. With the advance of forest clearance and the establishment of agriculture, ranching, and urban development, malaria transmission is substantially reduced, and risks of new infection are largely driven by human behavioral factors. Malaria mitigation strategies for frontier settlements require a combination of preventive and curative methods and close collaboration between the health and agricultural sectors. Of fundamental importance is matching the agricultural potential of specific plots to the economic and technical capacities of new migrants. Equally important is providing an effective agricultural extension service.Brazilian Amazon ͉ frontier malaria E conomically and politically driven human migration in the Amazon basin of Brazil over the past century has been accompanied by substantial ecosystem transformation and the promotion of malaria transmission (1-3). Research programs in parasitology, entomology, and epidemiology of vector-borne diseases were established in Brazil in the 1890s (4-6) followed, almost immediately, by translation into malaria mitigation strategies (3, 7). Major eradication and control campaigns in Amazonia, initiated in the 1950s and persisting until 1970 (1), succeeded in reducing the number of malaria cases in the region to Ϸ30,000 (in 1970) (roughly 60% of all cases reported in the country).The modern era of Amazon frontier expansion began during the military government with the introduction of large scale colonization projects focused on agriculture, mineral extraction, and wide-ranging human settlement (8-13). The human population of the Amazon grew from 7.2 million in 1970 to 11 million in 1980 and then to 18.7 million by 1996, accompanied by a dramatic increase in malaria cases (14, 15). As of 1999, there were Ϸ600,000 malaria cases in Brazil, 99.7% of which were concentrated in the legal Amazon. The spatial distribution of these cases was very irregular, and a lack of spatially targeted mitigation strategies resulted in inefficient allocation of resources. In 1986, 60% of all malaria cases in the Amazon were concentrated in 58% of the municipalities, but 70% of the budget for malaria control was spent in municipalities with only 3% of the cases (16).Characterizing malaria risk in the rapidly transforming Amazon ecosystems requires considering biological and ecological phenomena acting at multiple spatial scales, juxtaposed with behavioral and economic conditions. In this regard, we adapt and add precis...

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“…For example, during the dry season, reservoir capacity may be lowered considerably and the area under the flight range of mosquitoes may be considerably curtailed, placing some communities at less risk of acquiring the disease 49 . Nevertheless, this control strategy must be carefully planned, as it was observed that, when the Samuel dam in Brazil naturally reduced its water levels during the dry season, malaria incidence and Anopheles populations were exacerbated due to the exposure of new areas of land with stagnant water 79 . The efficiency of fluctuating reservoir water levels also depends on the correct maintenance of the banks, mainly reducing the amount of associated vegetation that may facilitate some mosquitoes to breed.…”

Section: Control In Water Development Projectsmentioning

confidence: 99%

Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology

Sánchez-Ribas

Parra-Henao²,

Guimarães³

2012

Rev. Inst. Med. trop. S. Paulo

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SUMMARYIrrigation schemes and dams have posed a great concern on public health systems of several countries, mainly in the tropics. The focus of the present review is to elucidate the different ways how these human interventions may have an effect on population dynamics of anopheline mosquitoes and hence, how local malaria transmission patterns may be changed. We discuss different studies within the three main tropical and sub-tropical regions (namely Africa, Asia and the Pacific and the Americas). Factors such as prehuman impact malaria epidemiological patterns, control measures, demographic movements, human behaviour and local Anopheles bionomics would determine if the implementation of an irrigation scheme or a dam will have negative effects on human health. Some examples of successful implementation of control measures in such settings are presented. The use of Geographic Information System as a powerful tool to assist on the study and control of malaria in these scenarios is also highlighted.

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Agricultural Colonization and Malaria on the Amazon Frontier

Cited by 70 publications

References 29 publications

Bayesian spatial modelling and the significance of agricultural land use to scrub typhus infection in Taiwan

Bayesian spatial modelling and the significance of agricultural land use to scrub typhus infection in Taiwan

Malaria risk on the Amazon frontier

Impact of dams and irrigation schemes in Anopheline (Diptera: Culicidae) bionomics and malaria epidemiology

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