Dengue virus in <i>Aedes aegypti</i> and <i>Aedes albopictus</i> in urban areas in the state of Rio Grande do Norte, Brazil: Importance of virological and entomological surveillance

<div><p>Background</p><p>Vector control remains the sole effective method to prevent dengue virus (DENV) transmission, although a vaccine for dengue has recently become available and testing of its efficacy and coverage is being performed in multiple places. Entomological surveillance is a key factor in alerting authorities to possible outbreaks, but until now natural DENV infection of mosquito populations has been scarcely used as an early warning system to monitor fluctuating prevalence of infected mosquitoes. The purpose of this study was to determine the burden of adult and larval/pupae of <i>Aedes aegypti</i> and <i>Aedes albopictus</i> with DENV in urban areas in the state of Rio Grande do Norte, Brazil.</p><p>Methodology/Principal findings</p><p>Immature insect forms (larvae and pupae) were collected from April 2011 to March 2012, whereas the collection of adults was conducted along 3 years: May 2011 to April 2014. Total RNAs of the samples were extracted and the nested reverse transcriptase PCR assay for detecting and typing DENV was performed. Of the 1333 immature insects collected during the study period, 1186 (89%) were <i>A</i>. <i>aegypti</i> and 147 (11%) <i>A</i>. <i>albopictus</i>. DENV-4 was identified in pools of <i>A</i>. <i>aegypti</i> larvae. The rate of DENV infection in immature <i>A</i>. <i>aegypti</i> was expressed as MIR = 3.37. DENV wasnot detected in immature <i>A</i>. <i>albopictus</i>. A total of 1360 adult female mosquitoes of the <i>Aedes</i> genus were captured from May 2011 to April 2014. Of this total, 1293 were <i>A</i>. <i>aegypti</i> (95%) and 67 were <i>A</i>. <i>albopictus</i> (5%). From the 130 pools studied, 27 (20.7%) were positive for DENV. DENV-1 was identified in 2/27 (7.4%) pools; 1of <i>A</i>. <i>albopictus</i> and 1 of <i>A</i>. <i>aegypti</i>. DENV-2 was identified in only 1/27 (3.7%) <i>A</i>. <i>aegypti</i> pools. DENV-4 was the most prevalent, identified in 24/27 (88.8%) of the positive pools, with 19 being of <i>A</i>. <i>aegypti</i> and 5 of <i>A</i>. <i>albopictus</i> pools. The minimum infection rate for adults of the <i>Aedes</i> genus was 19.8, considering both <i>A</i>. <i>aegypti</i> and <i>A</i>. <i>albopictus</i>.</p><p>Conclusions/Significance</p><p>This work represents the most complete study to date on the interaction between dengue viruses and <i>Aedes</i> mosquitoes in the State of Rio Grande do Norte, and raises important questions about a possible role of <i>A</i>. <i>albopictus</i> in the transmission of dengue virus in Brazil.</p></div

Study area.

<p>Map with the location point in the State of Rio Grande do Norte, Brazil. Areas where mosquitoes, larvae and pupae were collected. 1- Alecrim, 2- Felipe Camarão, 3- Nova Descoberta, 4- Potengi, and 5- Quintas. Note: This figure was created specifically for this manuscript by QGIS program. QGIS is a free and open-source cross-platform desktop geographic information system (GIS) application.</p

Minimum infection rate (MIR) for dengue virus in <i>Aedes aegypti</i> adults collected in urban areas in Natal, Rio Grande do Norte, Brazil.

<p>Minimum infection rate (MIR) for dengue virus in <i>Aedes aegypti</i> adults collected in urban areas in Natal, Rio Grande do Norte, Brazil.</p

Dengue virus in <i>Aedes albopictus</i> larvae and pupae collected in urban areas in Natal, Rio Grande do Norte, Brazil.

<p>Dengue virus in <i>Aedes albopictus</i> larvae and pupae collected in urban areas in Natal, Rio Grande do Norte, Brazil.</p

Minimum infection rate (MIR) for dengue virus in <i>Aedes aegypti</i> larvae and pupae collected in urban areas in Natal, Rio Grande do Norte, Brazil.

<p>Minimum infection rate (MIR) for dengue virus in <i>Aedes aegypti</i> larvae and pupae collected in urban areas in Natal, Rio Grande do Norte, Brazil.</p