Figure 1: Highway construction and dengue transmission are both expanding across the Brazilian Amazon.

Figure 1: Highway construction and dengue transmission are both increasing across the Brazilian Amazon. a) Highways expansion as of 2024 with health facilities shown as black points (n = 21,792). Government-maintained unpaved roads are shown in grey and navigable waterways are shown in blue. b) Highway construction time series shown across three periods with 2001 as the baseline. Annual data sourced from the Brazilian National Department of Transportation Infrastructure (DNIT). c) Brazilian Amazon municipalities colored by average dengue incidence from 2001–2024 with 2024 paved highways shown in black.

Figure 2: Preliminary staggered difference-in-difference results.

Increase in dengue cases after highway paving in previously non-endemic health facilities. Staggered difference-in-difference regression results of dengue cases between health facilities that experience highway paving and those connected to the transportation network via unpaved roads or rivers. Dynamic effects are represented by points, and 95% confidence intervals are represented by error bars. The average treatment effect on the treated (ATT) is represented by the horizontal red line, and 95% confidence intervals are represented by grey shading.

Figure 3: Heterogeneous treatment effects.

The effect of paving highways on dengue transmission varies by prior dengue history and highway project. Staggered difference-in-difference regression results of dengue cases between health facilities that experience highway paving and those connected to the transportation network via unpaved roads or rivers. Effect estimates are represented by points, and 95% simulation confidence intervals are represented by error bars. A) Dynamic average treatment effect on the treated (ATT) subset by health facilities’ dengue history prior to highway paving. B) Group-specific effects across specific highway projects (i.e., the overall effect for health facilities “treated” during the paving of a given highway). Projects with less than 40 health facilities treated were removed due to small sample size for plot legibility.

Figure 4: Year by year changes.

Figure 5: Major highway projects by number

This map displays the major highway projects in the Amazon colored by number/name. The grey/blue lines in the background show majoy navigable waterways.

Figure 6: Planned highways v current road network