Silent circulation of dengue virus in Aedes albopictus (Diptera: Culicidae) resulting from natural vertical transmission

Abstract

Vertical transmission in Aedes aegypti and Aedes albopictus is considered a maintenance mechanism for dengue virus (DENV) during unfavorable conditions and may be implicated in dengue outbreaks. Since DENV infection dynamics vary among wild-type viruses and vector populations, vertical transmission rates can also vary between regions. However, even though São Paulo is the most populous city in the Americas and has experienced major dengue epidemics, natural vertical transmission had never been detected in this area before. Here we confirm and describe for the first time natural vertical transmission of DENV-3 in two pools of male Ae. albopictus from the city of São Paulo. The detection of DENV-3 in years when no human autochthonous cases of this serotype were recorded suggests that silent circulation of DENV-3 is occurring and indicates that green areas may be maintaining serotypes that are not circulating in the human population, possibly by a vertical transmission mechanism.

An Updated Review Of the Invasive Aedes Albopictus in the Americas; The Minimum Infection Rate Suggests That Is More Efficient in the Vertical Than Horizontal Transmission of Arboviruses

“…Similarly, DENV-3 was detected in males of Ae. albopictus in years when no human autochthonous cases of this serotype were recorded in São Paulo, Brazil [33].…”

“…Notably, 11 out of 14 publications refer to transovarial transmission of dengue virus. This has several aspects; the dengue virus can remain and persist silently during inter-epidemic periods [21,33]. The dispersal of eggs and larvae of Ae.…”

“…In Brazil, the detection of DENV-3 in males of Ae. albopictus was carried out in years in which no autochthonous human cases with this serotype were recorded, suggesting that the silent circulation of DENV-3 occurs by a vertical transmission mechanism [33]. Additionally, also in Rio do Janeiro State, YFV was isolated in Ae.…”

“…Studies carried out in North and South America have found the dengue (all serotypes), Zika and La Crosse viruses in larvae and males of Ae. albopictus [20,[23][24][25][26][27][28][29][30][31][32][33]. Evidence suggests that the mosquito may have a reservoir role for the dengue virus by keeping it silent in nature [21].…”

An Updated Review of the Invasive <em>Aedes albopictus</em> in the Americas; Geographical Distribution, Host Feeding Patterns, Arbovirus Infection, and the Potential for Vertical Transmission of Dengue Virus

“…albopictus naturally infected with the dengue and Zika viruses come from Brazil, Mexico, Colombia, and Costa Rica, which are dengueendemic countries and between 2014 and 2018 there was active transmission of the Zika virus [10,11,14,47,[52][53][54][55][57][58][59][60][61][63][64][65][66][67][68]. Notably, in nine out of ten studies carried out in Brazil, dengue (all serotypes), Zika and yellow fever viruses were transmitted by transovarial route [47,[57][58][59][63][64][65][66]68]. Future studies should focus on finding out if there is an evolutionary relationship of arbovirus adaptation with vertical transmission of Ae.…”