Ecological and environmental factors affecting transmission of sylvatic yellow fever in the 2017–2019 outbreak in the Atlantic Forest, Brazil

Abstract

Background Yellow fever virus (YFV) is an arbovirus that, despite the existence of a safe and effective vaccine, continues to cause outbreaks of varying dimensions in the Americas and Africa. Between 2017 and 2019, Brazil registered un unprecedented sylvatic YFV outbreak whose severity was the result of its spread into zones of the Atlantic Forest with no signals of viral circulation for nearly 80 years. Methods To investigate the influence of climatic, environmental, and ecological factors governing the dispersion and force of infection of YFV in a naïve area such as the landscape mosaic of Rio de Janeiro (RJ), we combined the analyses of a large set of data including entomological sampling performed before and during the 2017–2019 outbreak, with the geolocation of human and nonhuman primates (NHP) and mosquito infections. Results A greater abundance of Haemagogus mosquitoes combined with lower richness and diversity of mosquito fauna increased the probability of finding a YFV-infected mosquito. Furthermore, the analysis of functional traits showed that certain functional groups, composed mainly of Aedini mosquitoes which includes Aedes and Haemagogus mosquitoes, are also more representative in areas where infected mosquitoes were found. Human and NHP infections were more common in two types of landscapes: large and continuous forest, capable of harboring many YFV hosts, and patches of small forest fragments, where environmental imbalance can lead to a greater density of the primary vectors and high human exposure. In both, we show that most human infections (~ 62%) occurred within an 11-km radius of the finding of an infected NHP, which is in line with the flight range of the primary vectors. Conclusions Together, our data suggest that entomological data and landscape composition analyses may help to predict areas permissive to yellow fever outbreaks, allowing protective measures to be taken to avoid human cases. Graphical Abstract

Dengue Prediction in Latin America Using Machine Learning and the One Health Perspective: A Literature Review

“…Finally, although the purpose of the present investigation was focused on ML applications in the field of dengue fever outbreaks, the holistic approach provides an open opportunity to learn from other vector-borne infectious diseases such as yellow fever [ 105 ]. Therefore, this study included a robust set of entomological data and landscape composition to predict areas permissive to yellow fever outbreaks.…”

Ecological, Genetic, and Phylogenetic Aspects of YFV 2017–2019 Spread in Rio de Janeiro State

“…This same type of matrix can be found throughout RJ, including the coastal and continental slopes of Serra do Mar, which may explain the similarity in dispersion speed. In addition, mosquito sampling in forest fragments on both slopes showed the same pattern: high YFV infection rates associated with low species richness and a high abundance of Haemagogus mosquitoes [ 28 ].…”

“…Entomological and epizootic surveillance must be constant in the SYF context. Several studies have described the genetic and phylogeographic patterns involving NHP epizootics and human cases in the recent outbreak [ 5 , 9 , 17 , 18 , 19 , 20 , 28 , 31 , 46 , 47 , 48 ]. In this study, however, a notable contribution is the unprecedented analysis of 29 YFV genomes from mosquito species belonging to five species of three genera.…”

“…scapularis , and Ae. taeniorhynchus , considered secondary vectors or opportunistic mosquitoes [ 15 , 28 ], contributed to only 1% of YFV samples.…”

“…However, multiple large less-populous counties of RJ are interspersed with patches of the preserved biodiversity-rich rain forest of variable extents. The state exhibits a peculiar ecological mosaic [ 28 , 29 , 30 ]. In RJ territory, forest areas with different distances from each other are associated with a diversity of altitudes and seasonal temperature differences.…”