Arbovirus vectors of epidemiological concern in the Americas: A scoping review of entomological studies on Zika, dengue and chikungunya virus vectors

Background Three arthropod-borne viruses (arboviruses) causing human disease have been the focus of a large number of studies in the Americas since 2013 due to their global spread and epidemiological impacts: Zika, dengue, and chikungunya viruses. A large proportion of infections by these viruses are asymptomatic. However, all three viruses are associated with moderate to severe health consequences in a small proportion of cases. Two mosquito species, Aedes aegypti and Aedes albopictus, are among the world´s most prominent arboviral vectors, and are known vectors for all three viruses in the Americas. Objectives This review summarizes the state of the entomological literature surrounding the mosquito vectors of Zika, dengue and chikungunya viruses and factors affecting virus transmission. The rationale of the review was to identify and characterize entomological studies that have been conducted in the Americas since the introduction of chikungunya virus in 2013, encompassing a period of arbovirus co-circulation, and guide future research based on identified knowledge gaps. Methods The preliminary search for this review was conducted on PubMed (National Library of Health, Bethesda, MD, United States). The search included the terms ´zika´ OR ´dengue´ OR ´chikungunya´ AND ´vector´ OR ´Aedes aegypti´ OR ´Aedes albopictus´. The search was conducted on March 1st of 2018, and included all studies since January 1st of 2013. Results A total of 96 studies were included in the scoping review after initial screening and subsequent exclusion of out-of-scope studies, secondary data publications, and studies unavailable in English language. Key findings We observed a steady increase in number of publications, from 2013 to 2018, with half of all studies published from January 2017 to March 2018. Interestingly, information on Zika virus vector species composition was abundant, but sparse on Zika virus transmission dynamics. Few studies examined natural infection rates of Zika virus, vertical transmission, or co-infection with other viruses. This is in contrast to the wealth of research available on natural infection and co-infection for dengue and chikungunya viruses, although vertical transmission research was sparse for all three viruses.Fil: Jones, Reilly. University of Toronto; CanadáFil: Kulkarni, Manisha A.. University of Ottawa; CanadáFil: Davidson, Thomas M.V.. University of Toronto; CanadáFil: Sander, Beate. Public Health Ontario; CanadáFil: González, Camila. Universidad de Los Andes; VenezuelaFil: Wu, Jianhong. York University ; CanadáFil: Miretti, Marcos Mateo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; ArgentinaFil: Espinel, Mauricio. Universidad Laica Elroy Alfaro de Manabí; EcuadorFil: Cevallos Viteri, Varsovia Enid. Instituto Nacional de Salud Pública; EcuadorFil: Cevallos, Varsovia. Instituto Nacional de Salud Pública; EcuadorFil: Talbot, Benoit. University of Ottawa; Canad

Development and deployment of low-cost, paper-based Zika diagnostics

The main aim of the project was to develop a low-cost test for Zika to be deployed first in Ecuador, Brazil, and Colombia. The test was expected to detect the virus in human and mosquito samples and, in turn, to help design effective surveillance programs

Assessing ZIKV transmission dynamics and mitigation strategies : a multidisciplinary approach : final report

A multi-country analysis based on entomological and socioeconomic data collected in three countries identified risk factors for Aedes mosquito density as a proxy for arbovirus transmission risk. Using computer simulation, the project aimed to identify a range of integrated Zika virus (ZIKV) intervention strategies and assess their comparative effectiveness, economic impact and cost-effectiveness. It was carried out in Latin American countries that have different epidemiological and ecological settings of Zika virus transmission (Colombia, Argentina and Ecuador), with the objective of characterizing the ecological transmission dynamics of ZIKV and designing integrated intervention approaches

Evaluación rápida de biodiversidad de mosquitos (Diptera: Culicidae) y riesgo en salud ambiental en un área Montana del Chocó Ecuatoriano

Se evaluó la diversidad alfa de mosquitos y el riesgo a transmisión de patógenos con base en variables de rápida determinación. El muestreo se realizó en: zona urbana-rural, rural y rural-selvática de tres provincias. Veintidos especies fueron colectadas: 59 % son vectores comprobados; 45,5 % como adultos; 90,9 % en fases inmaduras; dos especies únicamente como adultos (9 %) y 12 especies únicamente como inmaduros (54,5 %). Cuatro especies fueron comunes a las tres provincias, 12 restringidas a una localidad y 9 en zona urbana. El 31,8 % mostraron antropofília. El 75 % de viviendas mantenian larvas de Culicidae, con índice aédico IC= 25 %, de recipientes IR= 5 %; Bretaeu= 37,5 %, con 8,56 recipientes/vivienda. Los resultados sugieren alta vulnerabilidad a la traslocación y propagación de patógenos. Para la evaluación deben considerarse cinco factores: presencia/abundancia relativa de vectores potenciales; porcentaje de antropofília; zona urbana: índices aédicos y socioeconómicos; presencia de especies selváticas y asociación a viviendas en zonas de transición y el muestreo debe contemplar técnicas de colecta para ambas fases de desarrollo -inmaduros y adultos- para evitar una subestimación de hasta un 50 % de la diversidad alfa con solo capturas para adultos

Establishment, Genetic Diversity, and Habitat Suitability of <i>Aedes albopictus</i> Populations from Ecuador

Aedes albopictus, also known as the tiger mosquito, is widespread worldwide across tropical, subtropical, and temperate regions. This insect is associated with the transmission of several vector-borne diseases, and, as such, monitoring its distribution is highly important for public health. In Ecuador, Ae. albopictus was first reported in 2017 in Guayaquil. Since then, the vector has been identified in the Northeastern lowlands and the Amazon basin. This study aims to determine the genetic diversity of Ecuadorian populations of Ae. albopictus through the analysis of the mitochondrial gene COI and to describe the potential distribution areas of this species within the country. The genetic diversity was determined by combining phylogenetic and population genetics analyses of five localities in Ecuador. Results showed two haplotypes in the Ecuadorian populations of Ae. albopictus. Haplotype 1 (H1) was found in the coastal and Amazon individuals, while haplotype 2 (H2) was only found in the three northeastern lowlands sites. In a worldwide context, H1 is the most widespread in 21 countries with temperate and tropical habitats. In contrast, H2 distribution is limited to five countries in tropical regions, suggesting fewer adaptation traits. Our prediction model showed a suitable habitat for Ae. albopictus in all regions (coastal, Amazon basin, and Andean lowland regions and the Galápagos Islands) of Ecuador. Hence, understanding different aspects of the vector can help us implement better control strategies for surveillance and vectorial control in Ecuador

The biting rate of Aedes aegypti and its variability: A systematic review (1970-2022).

BACKGROUND: Transmission models have a long history in the study of mosquito-borne disease dynamics. The mosquito biting rate (MBR) is an important parameter in these models, however, estimating its value empirically is complex. Modeling studies obtain biting rate values from various types of studies, each of them having its strengths and limitations. Thus, understanding these study designs and the factors that contribute to MBR estimates and their variability is an important step towards standardizing these estimates. We do this for an important arbovirus vector Aedes aegypti. METHODOLOGY/PRINCIPAL FINDINGS: We perform a systematic review using search terms such as biting rate and biting frequency combined with Aedes aegypti (Ae. aegypti or A. aegypti). We screened 3,201 articles from PubMed and ProQuest databases, of which 21 met our inclusion criteria. Two broader types of studies are identified: human landing catch (HLC) studies and multiple feeding studies. We analyze the biting rate data provided as well as the methodologies used in these studies to characterize the variability of these estimates across temporal, spatial, and environmental factors and to identify the strengths and limitations of existing methodologies. Based on these analyses, we present two approaches to estimate population mean per mosquito biting rate: one that combines studies estimating the number of bites taken per gonotrophic cycle and the gonotrophic cycle duration, and a second that uses data from histological studies. Based on one histological study dataset, we estimate biting rates of Ae. aegypti (0.41 and 0.35 bite/mosquito-day in Thailand and Puerto Rico, respectively). CONCLUSIONS/SIGNIFICANCE: Our review reinforces the importance of engaging with vector biology when using mosquito biting rate data in transmission modeling studies. For Ae. aegypti, this includes understanding the variation of the gonotrophic cycle duration and the number of bites per gonotrophic cycle, as well as recognizing the potential for spatial and temporal variability. To address these variabilities, we advocate for site-specific data and the development of a standardized approach to estimate the biting rate

Two Haplotypes of <i>Aedes aegypti</i> Detected by ND4 Mitochondrial Marker in Three Regions of Ecuador

Aedes aegypti, also known as the yellow fever mosquito, is the main vector of several arboviruses. In Ecuador, dengue and chikungunya are the most prevalent mosquito-borne diseases. Hence, there is a need to understand the population dynamics and genetic structure of the vector in tropical areas for a better approach towards effective vector control programs. This study aimed to assess the genetic diversity of Ae. aegypti, through the analyses of the mitochondrial gene ND4, using a combination of phylogenetic and population genetic structure from 17 sites in Ecuador. Results showed two haplotypes in the Ecuadorian populations of Ae. aegypti. Haplotype 1 was closely related to Ae. aegypti reported from America, Asia, and West Africa. Haplotype 2 was only related to samples from America. The sampled vectors from the diverse localities showed low nucleotide diversity (π = 0–0.01685) and genetic differentiation (FST = 0.152). AMOVA analyses indicated that most of the variation (85–91%) occurred within populations, suggesting that geographical barriers have little effect on the genetic structure of Ecuadorian populations of Ae. aegypti. These results agree with the one main population (K = 1) detected by Structure. Vector genetic identity may be a key factor in the planning of vector control strategies