New research published in Communications Earth & Environment on June 22 links the clustering of vector-borne diseases in the Brazilian Amazon to patterns of land use, economic activity, and poverty. The study examines how forest-linked livelihoods, mining, large-scale agriculture, and socioeconomic conditions shape where diseases such as malaria, dengue fever, leishmaniasis, and Chagas disease overlap.
Researchers aggregated data from 2015 to 2019 using Technoproductive Trajectories (TTs) and Trajetórias datasets. During this period, there were 1.28 million reported cases of vector-borne diseases in the region. Malaria accounted for 75% of these cases while dengue represented about 20%. Rural areas experienced higher notification rates for Chagas disease, malaria, and American tegumentary leishmaniasis (ATL), whereas urban areas saw more visceral leishmaniasis (VL). The dataset did not stratify dengue by rural or urban setting.
The team used a generalized linear latent variable model to analyze how socioeconomic structures and ecological transformations influenced disease distribution across municipalities. They found that Chagas disease was likely to co-occur with malaria; similarly, dengue tended to cluster with ATL. VL appeared isolated from other diseases. Including environmental and socioeconomic factors in their model explained nearly three-fourths of the covariance among these diseases.
High deforestation rates and rural poverty were strongly associated with overlapping cases of urban and rural Chagas disease within municipalities. Mining activities correlated with both Chagas disease types; larger river networks were linked specifically to rural Chagas cases, while agricultural land use related more closely to urban occurrences. Municipalities dominated by cattle ranching or large-scale agriculture had lower incidences of both malaria and Chagas disease but showed increased clustering for dengue and ATL.
Geographically, a major hotspot for both malaria and Chagas disease was identified in the Western Amazon—areas characterized by peasant-based agriculture—while hotspots for dengue-ATL clusters appeared mainly in regions dominated by livestock farming or agricultural exports in the southeast Amazon.
The authors concluded that economic scenarios significantly influence biosocial conditions underlying vector-borne disease clustering across the Amazon basin. They emphasized integrating environmental, climatic, and socioeconomic factors into unified public health strategies rather than relying solely on conventional single-disease control efforts. Limitations cited include reliance on reported diagnoses only—which may underestimate true incidence—and lack of detailed stratification or seasonal analysis.
