Long-lasting transition toward sustainable elimination of desert malaria under irrigation development

Abstract

In arid areas, people living in the proximity of irrigation infrastructure are potentially exposed to a higher risk of malaria due to changes in ecohydrological conditions that lead to increased vector abundance. However, irrigation provides a pathway to economic prosperity that over longer time scales is expected to counteract these negative effects. A better understanding of this transition between increased malaria risk and regional elimination, in particular whether it is slow or abrupt, is relevant to sustainable development and disease management. By relying on space as a surrogate for stages of time, we investigate this transition in a semidesert region of India where a megairrigation project is underway and expected to cover more than 1,900 million hectares and benefit around 1 million farmers. Based on spatio-temporal epidemiological cases of Plasmodium vivax malaria and land-use irrigation from remote sensing sources, we show that this transition is characterized by an enhanced risk in areas adjacent to the trunk of the irrigation network, despite a forceful and costly insecticide-based control. Moreover, this transition between climate-driven epidemics and sustained low risk has already lasted a decade. Given the magnitude of these projects, these results suggest that increased health costs have to be planned for over a long time horizon. They further highlight the need to integrate assessments of both health and environmental impacts to guide adaptive mitigation strategies. Our results should help to define and track these transitions in other arid parts of the world subjected to similar tradeoffs.vector-borne diseases | agricultural development | epidemic malaria | irrigation gradient | environmental health

Relationships of climate and irrigation factors with malaria parasite incidences in two climatically dissimilar regions in India

“…Climatic variables (temperature and humidity) related to irrigation practices have been considered as the important environmental factors for malaria transmission, especially in arid environments (Baeza et al, 2011;Keiser et al, 2005;Tyagi, 2004;Akhar and McMichael, 1996). In arid areas, people living in the proximity of irrigation infrastructure are potentially exposed to a higher risk of malaria due to changes in eco-hydrological and eco-climatological conditions that lead to increased vector abundance (Baeza et al, 2013).…”

Environmental change and Rift Valley fever in eastern Africa: projecting beyond HEALTHY FUTURES

“…Ethiopia (Kibret et al, 2014), by bringing about an increased incidence of malaria -the so-called paddies paradox (Ijumba and Lindsey, 2001). Often these negative health effects of development are temporary (Baeza et al, 2013), as the associated increased wealth as a result of raised agricultural productivity eventually bring about improvements in nutrition, housing, sanitation, education and access to health services. The pathogenic landscape may be more resistant to positive changes in the case of the communities impacted by RVF outbreaks, however.…”

Climate and health in Africa

“…For example, estimations of air temperature derived from Moderate-Resolution Imaging Spectro-radiometer (MODIS) Land Surface Temperature products Ceccato et al 2010) were developed and provided to the user community to assess risks of malaria transmission in the highland regions of Africa. Maps of water bodies and vegetation using the MODIS sensor at 250 metre spatial resolution were developed and integrated into vector-borne disease risk models (Baeza et al 2013;Ceccato et al 2006). Additionally, a Vectorial Capacity Model (VCAP) has been designed to include the influence of rainfall and temperature variables on the potential for malaria transmission.…”