Invasion of Ae. albopictus in forests of Central Africa and the risk of emergence of new zoonotic viruses

Informations

Funding country

France

Acronym

TIGERBRIDGE

URL

-

Start date

1/1/2016

End date

-

Budget

468,667 EUR

Fundings

Abstract

Aedes (Stegomyia) albopictus, an invasive mosquito species with its origins in the forested areas of Southeast Asia, has recently spread across the world including in Europe and Central Africa. Ae. albopictus supports the development and transmission of numerous arboviruses under laboratory conditions, and is now recognized as a primary vector of dengue (DENV), chikungunya (CHIKV) and zika (ZIKAV). Since it was first reported in Central Africa in 2000, Ae. albopictus has gradually spread over most of this region to become the dominant species in urban and rural environments. In parallel with its expansion there has been an increase in outbreaks of DENV, CHIKV and ZIKAV and new viral strains have been selected (CHIKV). Overall, the spread of Ae. albopictus in Central Africa, with consequent replacement of autochthonous mosquitoes, disruption of epidemiological equilibriums, and selection of new viral variants causing massive urban or rural outbreaks, has caused a major and dramatic reshuffling of the epidemiology of arborviruses. The region is now a source of viruses with the ability to spread throughout and beyond Africa through the increased flow of international travelers. We think the impacts on health will increase. From what is known of the biology of Ae. albopictus in its native area, there is no doubt that the ecological limits in Central Africa have not been reached yet. The species is currently mainly reported in the anthropogenic compartment but could also easily invade the forest compartment due to its propensity to exploit natural water collections (rock and tree holes) and its significant appetence for animals. This pattern is consistent with what we observed in Gabon during a pilot study carried out in 2014 in the national wildlife reserve of La Lopé. Aedes albopictus has spread from villages to a number of remote forest locations indicating interaction with wild hosts as blood sources. The wildlife in the La Lopé National Park includes several groups of potential reservoirs of enzootic mosquito-borne viruses transmitted by sylvan Aedes species (subgenus Stegomyia), which are phylogenetically related to Ae. albopictus. In such a context we hypothesize that the spread of Ae. albopictus in forested areas will have multiple impacts on: i) resident sylvan mosquito communities through competitive interactions; ii) viral enzootic cycles, through its proven vector competence for a range of circulating viruses and appetence for animal bloodmeals; iii) virus evolution, eventually leading to the emergence of new viruses and their transfer to humans. Therefore, with respect to health issues at both local and global levels, it is essential and urgent to assess the ecological and epidemiological consequences of the spread of the tiger mosquito into the evergreen forests of Central Africa. This is the framework of the TIGERBRIDGE project, which takes a highly innovative approach to this important issue to attain its main aim, “to monitor and understand how Aedes albopictus invades the forest ecosystems of Central Africa, and, given its increasing contact with wildlife, to establish which zoonotic viruses could spread to human populations”. TIGERBRIDGE is built on a robust consortium (4 partners: the MIVEGEC, EPV and UMMISCO units and IPB), which brings together the necessary complementary fields and tasks (x6) to achieve its ultimate objective.