Roads and forest edges facilitate yellow fever virus dispersion

Abstract

1. Landscape connectivity is important for a wide range of ecological processes, including to disease spread, once it describes the degree to which landscapes facilitate or impede vector and hosts dispersion. Understanding connectivity is extremely important to identify where pathogens can move, and at what speed, allowing the organization of vaccination campaigns or other preventive measures.2. To better understand the effects of landscape connectivity on yellow fever virus (YFV) dispersion in Brazil, we used a network approach and modelled the movement of non-human primates' cases, the so-called epizootic events, over time. The networks consider each epizootic event as a node and the dispersion between nodes as links. Those links were established considering, respectively, the date of each epizootic event, the distance among the nodes and the permeability of the landscape between each pair of nodes.3. Our results demonstrated that on average YFV dispersed 1.42 km/day, with the largest movement being 6.9 km/day. Dispersions were longer in summer (1.2 km/day) than in winter (0.22 km/day). Most dispersal movements occurred up to 1 km/day (71%) and within a week after the arrival of the virus in the source node (73%), except in winter, where dispersions occurred within a period of up to 20 days. The best model indicates that YFV disperses mainly through roads adjacent to forest areas, and along forest edges (within a range of 100 m) in interface with agricultural areas, water and forestry areas. Core areas of urban, agricultural and forest regions were important barriers for virus movement.

Vegetation cover and biodiversity reduce parasite infection in wild hosts across ecological levels and scales

“…The amount of forest edges in the landscape decreased infection rates, both at the individual and at the community levels, which may be explained by the positive correlation between forest edges and vegetation cover, and the positive effect of these landscape variables on small mammal taxonomic diversity and relative frequency of rodents in the community. Although forest edges had already been related to increased transmission of several infectious diseases such as yellow fever (Prist et al 2022), malaria (Medeiros‐Sousa et al 2019) and spotted fever (Scinachi et al 2017) through its effects on vector abundance, we show that when considering the host communities, these relationships are not straightforward. In our case, forest edges were not related to vegetation cover in the Atlantic Forest and positively related to forest cover in the Amazon, which indicate that those edges may be increasing habitat heterogeneity and favoring a higher diversification of small mammal communities and reducing the dominance of superabundant species.…”

Protecting Brazilian Amazon Indigenous territories reduces atmospheric particulates and avoids associated health impacts and costs

“…So, this result only reinforces a pattern of forest area configuration and not quantity. Still, more studies are needed to this result and especially to find a threshold of coverage and fragmentation beyond which the provision of this service is lost; (2) more fragmented forest areas can also increase the transmission risk of zoonotic diseases 57,58 . Therefore, trade-offs within the human health maintenance service must be better balanced and evaluated.…”

Alarming patterns of mature forest loss in the Brazilian Atlantic Forest

“…The biome is characterized by a prolonged history of degradation and exists with a signi cant portion below the extinction threshold, rendering it highly vulnerable to degradation processes 7 , 20 . This degradation leads to a reduction in the ability to address climate change and an exacerbation of the risks of zoonotic disease spread 21 . The average observed deforestation rates of approximately 18,000 ha per year are high and surprising, considering that those mature forests are strongly protected by law, the biome has a high level of surveillance, there are several protected areas and a diffuse and consistent network of forest protection organizations 22 .…”