Evidências de um ciclo silvestre do Dengue virus nas americas

Abstract

Dengue virus belongs to the Flaviviridae family, which comprises genomic RNA virus, single stranded negative sense, enveloped, viruses vectored by arthropods. DENV can cause a mild disease, named dengue fever (DF), until severe disease with bleeding, named dengue hemorrhagic fever (DHF). Human activities like: animals traffic, people circulation, reforestation and others, are factors that contribute to DENV and other arboviruses emergence. The ecological cycle of DENV is complex and not completely understood. DENV circulates in Asia and Americas vectored to humans by the vector of Aedes genus. In Africa, occurs predominantly DENV wild circulation. In Americas, wild animals have no confirmed role in DENV cycle. Recent studies suggest a possible secondary cycle of amplification involving mammalian non-primates such as rodents, marsupials and bats. But, if those animals keep the DENV in an enzootic cycle and it plays a role in DENV emergence is not well elucidated. Thus, this study aims to assess and discuss the relevance of epidemiological findings, involving the detection of viral genome and neutralizing antibodies against DENV, in organs or serum of wild animals in the region of French Guiana (GF) and in Mexican bats, besides neutralizing antibodies in bats of Costa Rica and Ecuador, in the maintenance of DENV and possible natural reservoirs. The low similarity between samples of DENV-1 isolated from wild animals in the GF and samples of DENV-1 endemic in humans in the same region, suggest a wild movement of DENV in the region. DENV-2 isolated from animals in the GF seems to be associated with possible non-human host reservoirs and may be related to a sylvatic cycle in the region. However, further studies should be conducted so that we can characterize the maintenance of DENV reservoir through a non-human mammal, not just an occasional infection from wildlife. DENV-3 isolated in GF looks to be related to a regional virus circulation in a wild host-reservoir during inter-epidemic periods. A strong clue to this is also the great similarity between samples isolated from wild animals with samples isolated from mosquitoes (99,1-99,7% of nt and 99-100% of aa). One hundred percent of identity between DENV detected in the same animal species in different periods suggests the involvement of this species in the circulation of DENV. Serological and molecular tests performed on Mexican bats, and neutralizing antibodies found in bats from Costa Rica and Ecuador, although inconclusive for the occurrence of an active infection and possible role of wild animals in the DENV cycle, represent strong evidence for this assertion. The data presented here do not respond all the questions about the possible DENV sylvatic cycle in America, or the wild animals role as a natural reservoir of DENV. For this, new research should be conducted in order to better understand the DENV replication cycle in different environments, so we can trace the best epidemiological strategy against it.