Conservation Efforts and Malaria in the Brazilian Amazon

Abstract

Abstract. We respond to Valle and Clark, 1 who assert that "conservation efforts may increase malaria burden in the Brazilian Amazon," because the relationship between forest cover and malaria incidence was stronger than the effect of the deforestation rate. 1 We contend that their conclusion is flawed because of limitations in their methodology that we discuss in detail. Most important are the exclusion of one-half the original data without a discussion of selection bias, the lack of model adjustment for either population growth or migration, and the crude classifications of land cover and protected areas that lead to aggregation bias.1 Of greater significance, we stress the need for caution in the interpretation of data that could have profound effects on regional land use decisions.In a recent article, Valle and Clark 1 found that, in 401 cities in the Brazilian Amazon, both deforestation and percent forest cover in a 20-km area around cities were associated with an increase in malaria cases reported to the primary health clinic in the city. Valle and Clark 1 conclude that "conservation efforts may increase malaria burden in the Brazilian Amazon," because the relationship between forest cover and malaria was stronger than the effect of the deforestation rate.

Public health impacts of ecosystem change in the Brazilian Amazon

“…However, as summarized in SI Appendix, Table S1, different policies for reducing deforestation could have very different effects on human exposure to disease, separate from any disease regulation resulting from ecosystem conservation. For example, strict PAs are likely to decrease exposure more than sustainableuse PAs (31). Roads increase mobility and hence both the spread of disease and access to medical services.…”

“…The thin evidence base focuses on specific drivers of specific diseases (6), typically climate (20)(21)(22)(23)(24)(25), biodemography and migration (13,(26)(27)(28)(29)(30), or land-use change (20,(31)(32)(33). Expanding this literature into multifactorial analyses could provide a more comprehensive picture of the human ecology of these diseases, including the role of specific behaviors and policies (8,34).…”

Response to the Critique by Hahn and Others Entitled “Conservation and Malaria in the Brazilian Amazon”

“…Hahn and others 1 then criticize the land use/land cover classification product that we used in our analysis. Interestingly, Hahn and others 1 have also used the same remote sensing product to implicate deforestation in malaria risk.…”

“…Hahn and others 1 have recently written a perspective piece, which was published in The American Journal of Tropical Medicine and Hygiene, criticizing our study published in 2013. 2 Here, we respond to their critique, commenting and clarifying some of the points raised.…”

“…Hahn and others 1 provide literature that supports their view that intact forests can help eliminate local malaria transmission. They 1 place special emphasis on a study that was based on a theoretical model parameterized to a different vector and applied to a completely different ecosystem (~1,000 km away from our study region) on a region that has not had any reported malaria cases for the past 30 years.…”