The vertical stratification of potential bridge vectors of mosquito-borne viruses in a central Amazonian forest bordering Manaus, Brazil

Adam Hendy,Eduardo Hernandez-Acosta,Nikos Vasilakis,Danielle Valério,Claudia Mendonça,Michaela Buenemann,Kathryn A Hanley,Vera Margarete Scarpassa,José Tenaçol Andes Júnior,Marcus Vinícius Guimarães De Lacerda,Flamarion Prado Assunção,Edson Rodrigues Costa,Marcelo Gordo,Nelson Ferreira Fé

doi:10.1038/s41598-020-75178-3

Abstract

The emergence of Zika virus (ZIKV) in Latin America brought to the fore longstanding concerns that forests bordering urban areas may provide a gateway for arbovirus spillback from humans to wildlife. To bridge urban and sylvatic transmission cycles, mosquitoes must co-occur with both humans and potential wildlife hosts, such as monkeys, in space and time. We deployed BG-Sentinel traps at heights of 0, 5, 10, and 15 m in trees in a rainforest reserve bordering Manaus, Brazil, to characterize the vertical stratification of mosquitoes and their associations with microclimate and to identify potential bridge vectors. Haemagogus janthinomys and Sabethes chloropterus, two known flavivirus vectors, showed significant stratification, occurring most frequently above the ground. Psorophora amazonica, a poorly studied anthropophilic species of unknown vector status, showed no stratification and was the most abundant species at all heights sampled. High temperatures and low humidity are common features of forest edges and microclimate analyses revealed negative associations between minimum relative humidity, which was inversely correlated with maximum temperature, and the occurrence of Haemagogus and Sabethes mosquitoes. In this reserve, human habitations border the forest while tamarin and capuchin monkeys are also common to edge habitats, creating opportunities for the spillback of mosquito-borne viruses.

Highlights

The emergence of Zika virus (ZIKV) in Latin America brought to the fore longstanding concerns that forests bordering urban areas may provide a gateway for arbovirus spillback from humans to wildlife
To elucidate potential bridge vectors, we previously investigated the distribution of mosquitoes in urban parks in Manaus, Brazil[19]
Manaus is a city of more than 2 million people surrounded by the Amazon rainforest, where abrupt urban-forest edges bring humans and animals into close contact and where DENV, CHIKV, and ZIKV circulate regularly

Summary

Introduction

The emergence of Zika virus (ZIKV) in Latin America brought to the fore longstanding concerns that forests bordering urban areas may provide a gateway for arbovirus spillback from humans to wildlife. The virus has not been isolated from free-living forest mosquitoes, at present, only low-numbers of the most likely sylvatic vector species have been screened[16,17] In light of these developments, there is a need to identify the species best poised to act as bridge vectors that could transfer ZIKV from humans to wildlife and back again. Manaus is a city of more than 2 million people surrounded by the Amazon rainforest, where abrupt urban-forest edges bring humans and animals into close contact and where DENV, CHIKV, and ZIKV circulate regularly In these parks, Ae. albopictus and Ae. aegypti penetrated at least 100 m from the urban edge and may serve as bridge vectors if they feed on both humans and monkeys. There is serological evidence that Hg. janthinomys and Hg. leucocelaenus feed on a range of other vertebrates including birds, rodents, and marsupials[27,28]

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Discussion

Conclusion