Outbreaks of Vector-Borne and Zoonotic Diseases Are Associated With Changes in Forest Cover and Oil Palm Expansion at Global Scale

Abstract

Deforestation is a major cause of biodiversity loss with a negative impact on human health. This study explores at global scale whether the loss and gain of forest cover and the rise of oil palm plantations can promote outbreaks of vector-borne and zoonotic diseases. Taking into account the human population growth, we find that the increases in outbreaks of zoonotic and vector-borne diseases from 1990 to 2016 are linked with deforestation, mostly in tropical countries, and with reforestation, mostly in temperate countries. We also find that outbreaks of vector-borne diseases are associated with the increase in areas of palm oil plantations. Our study gives new support for a link between global deforestation and outbreaks of zoonotic and vector-borne diseases as well as evidences that reforestation and plantations may also contribute to epidemics of infectious diseases. The results are discussed in light of the importance of forests for biodiversity, livelihoods and human health and the need to urgently build an international governance framework to ensure the preservation of forests and the ecosystem services they provide, including the regulation of diseases. We develop recommendations to scientists, public health officers and policymakers who should reconcile the need to preserve biodiversity while taking into account the health risks posed by lack or mismanagement of forests.

Keywords: deforestation; governance; infectious diseases; oil palm; public health; vector-borne diseases; zoonoses.

Figure 1

(A) Number of outbreaks of zoonotic diseases worldwide from 1990 to 2016 (data obtained from GIDEON). (B) Number of outbreaks of vector-borne diseases worldwide from 1990 to 2016 (data obtained from GIDEON). (C) Global change in forest cover (in share of global land) from 1990 to 2016 (data obtained from World Bank). (D) Relationship between the number of outbreaks of zoonotic diseases worldwide and the change in forest cover from 1990 to 2016. (E) Relationship between the number of outbreaks of vector-borne diseases worldwide and the change in forest cover from 1990 to 2016. Fitted smooth regressions (in blue) with confidence intervals (in light blue) are shown.

Figure 2

(A) Association between the change in forest cover and the number of outbreaks of zoonotic diseases from 1990 to 2016. (B) Association between the change in forest cover and the number of outbreaks of vector-borne diseases from 1990 to 2016. (C) Association between the change in palm oil areas and the number of outbreaks of zoonotic diseases from 1990 to 2016. (D) Association between the change in palm oil areas and the number of outbreaks of vector-borne diseases from 1990 to 2016. Fitted smooth regressions (in blue) with confidence intervals (in light blue) are shown (data from GIDEON and FAOSTAT).

Figure 3

Results of General additive modeling (GAM) explaining: the number the number of outbreaks of zoonotic diseases with (A) forest cover (controlling for year) and (B) human population size (controlling for year) (see Table 1, model 1); the number the number of outbreaks of vector-borne diseases with (C) forest cover (controlling for year) and (D) human population size (controlling for year) (see Table 1, model 2); the number the number of outbreaks of zoonotic diseases with (E) oil palm area (controlling for year) and (F) human population size (controlling for year) (see Table 1, model 3); the number the number of outbreaks of vector-borne diseases with (G) oil palm area (controlling for year) and (H) human population size (controlling for year) (see Table 1, model 4) (data from GIDEON, FAOSTAT and World Bank).

Figure 4

Maps of significant association between forest cover change (deforestation in brown, reforestation in blue) and (A) outbreaks of zoonotic diseases and (B) outbreaks of vector-borne diseases on temporal trends from 1990 to 2016. Maps of significant association between oil palm area change and (C) outbreaks of zoonotic diseases and (D) outbreaks of vector-borne diseases (positive association in brown, negative association in blue) on temporal trends from 1990 to 2016 (data from GIDEON and FAOSTAT) (see Supplementary File).

Figure 5

Density plot of significant association between outbreaks of zoonotic and vector-borne diseases with deforestation (in red) or reforestation (in green) in relation to latitudinal gradient.