A high-risk Zika and dengue transmission hub: virus detections in mosquitoes at a Brazilian university campus

Abstract

BackgroundZika virus (ZIKV) and dengue virus (DENV) are mosquito-borne flaviviruses prevalent throughout tropical regions. Currently, management of ZIKV and DENV centers on control of the primary vector Aedes aegypti. This vector is highly anthropophilic and is therefore prevalent throughout densely urbanised landscapes. A new passive trap for gravid Ae. aegypti (Gravid Aedes Trap - GAT) was developed for mosquito surveillance. Here the different killing agents and the level of transmission of arboviruses that may occur in mosquitoes sampled by GATs are assessed for the first time.MethodsGravid Aedes traps (GATs) were deployed at the Federal University of Minas Gerais campus, in Belo Horizonte, Brazil to sample Ae. aegypti. Three different killing agents were evaluated within the GATs: sticky cards, long-lasting insecticide-impregnated nets (LLINs) and canola oil. Traps were monitored weekly for 14 weeks then mosquito specimens were identified to the species level and Ae. aegypti catches were pooled and submitted to qRT-PCR assays for to DENV and ZIKV virus detection, followed by Bayesian phylogenetic analysis of the ZIKV. Additionally, comparisons of means were performed on transformed weekly catch data (P = 0.05, t-tests) with the stats package of the R statistical software.ResultsIn total, 1506 female Ae. aegypti were captured using GATs, with traps using sticky cards catching more mosquito than those using either LLINs or canola oil. Both ZIKV and DENV were detected in Ae. aegypti females captured over several weeks suggesting that this highly populated university campus may have served as a significant transmission hub. The infection rate for ZIKV was present in seven (8.5%) pools from four weeks while DENV was detected in four (4.9%) pools from four weeks. Phylogenetic analysis of ZIKV classified the strain as Asian genotype.ConclusionsThe Federal University of Minas Gerais and similar organizations must strongly consider monitoring Ae. aegypti populations and reinforcing personal protection of staff and students during seasons of high mosquito activity.

Entomological and virological surveillance for dengue virus in churches in Merida, Mexico

“…In Belo Horizonte, Brazil, both DENV and ZIKV were detected in Ae. aegypti collected at a university 32 . Furthermore, La Crosse virus was detected in Aedes triseriatus in cemeteries in Tennessee, USA 33 .…”

Prevalence of dengue, Zika and chikungunya viruses in Aedes (Stegomyia) aegypti (Diptera: Culicidae) in a medium-sized city, Amazon, Brazil

“…This is corroborated by Baak-Baak et al 23 , who found 1.2% (2/166) positivity for dengue virus in churches. Meanwhile, in Belo Horizonte, the State capital of Minas Gerais, Eiras et al 24 found 4.9% (4/82 pools) and 8.5% (7/82 pools) infectivity to dengue virus and Zika virus, respectively, at the university Moreover, the possibility of transovarian transmission of dengue 25 , chikungunya 26 and Zika 27,28 in Ae. aegypti shows that a varied percentage of mosquitoes can be infected with these viruses.…”

Detection of arboviruses in mosquitoes: Evidence of circulation of chikungunya virus in Iran

“…We failed to isolate the virus and to perform whole genome sequencing. The infection rate of 0.5% in mosquitoes we have obtained is lower than what could be estimated during an epidemic [29]. However this screening method can be used as a passive surveillance system alerting of any increase in infection rates in mosquitoes, sign of an imminent epidemic.…”