Biology subjects

Cevallos, V.

Publications and source records attributed to Cevallos, V..

6 recordsLinked to original sources

bioRxiv2024

A numbers game: Mosquito-based arbovirus surveillance in two distinct geographic regions of Latin America

Aedes mosquitoes, as vectors of medically important arthropod-borne viruses (arboviruses), constitute a major public health threat that requires entomological and epidemiological surveillance to guide vector control programs to prevent and reduce disease transmission. In this study, we present the collaborative effort of one year of mosquito-based arbovirus surveillance in two geographically distinct regions of Latin America (Nicaragua and Ecuador). Adult female mosquitoes were collected using backpack aspirators in over 2,800 randomly selected households (Nicaragua, Ecuador) and 100 key sites (Nicaragua) from eight distinct communities (Nicaragua: 2, Ecuador: 6). A total of 1,358 mosquito female pools were processed for RNA extraction and viral RNA detection using real-time RT-PCR. Ten positive dengue virus (DENV) pools were detected (3 in Nicaragua and 7 in Ecuador), all of which were found during the rainy season and matched the serotypes found in humans (Nicaragua: DENV-1 and DENV-4; Ecuador: DENV-2). Infection rates ranged from 1.13 to 23.13, with the Nicaraguan communities having the lowest infection rates. Our results demonstrate the feasibility of detecting DENV-infected Aedes mosquitoes in low-resource settings and underscore the need for targeted mosquito arbovirus sampling and testing, providing valuable insights for future surveillance programs in the Latin American region.

ecology↗

bioRxiv2024

Whole Genome Sequencing of DENV-2 isolated from Aedes aegypti mosquitoes in Esmeraldas, Ecuador. Genomic epidemiology of genotype III Southern Asian-American in the country.

Ecuador is a tropical country reporting Dengue virus (DENV) outbreaks with areas of hyperendemic viral transmission. Entomo-virological surveillance and monitoring effort conducted in the Northwestern border province of Esmeraldas in April 2022, five pools of female Aedes aegypti mosquitoes from a rural community tested positive for DENV serotype 2 by RT-qPCR. One pool was sequenced by Illumina MiSeq, and it corresponded to genotype III Southern Asian-American. Comparison with other genomes revealed genetic similarity to a human DENV genome sequenced in 2021, also from Esmeraldas. Potential introduction events to the country could have originated from Colombia, considering the vicinity of the collection sites to the neighboring country and high human movement. The inclusion of genomic information complements entomo-virological surveillance, providing valuable insights into genetic variants. This contribution enhances our understanding of Dengue virus (DENV) epidemiology in rural areas and guides evidence-based decisions for surveillance and interventions. Author SummaryIn this study, the complete genetic information of the dengue virus isolated from the mosquito vector Aedes aegypti was characterized using molecular biology, sequencing, and bioinformatics analysis. The isolation of the virus from the vector has contributed significantly to our understanding of the transmission dynamics of the disease and its genetic relationship with human cases. Identifying the serotypes and genotypes circulating in Ecuador has enabled us to comprehend the evolution of the virus from 2014 to 2023. Therefore, surveillance of genetic variability would aid in adapting precise prevention and control strategies to the genetic variants present in a specific geographical area. Entomo-virological surveillance is essential for assessing changes in risk and the impact of control measures.

genomics↗

bioRxiv2021

Mosquitoes (Diptera: Culicidae) of Ecuador: A revised checklist, new records and species of medical importance.

Ecuador is one of the countries with the highest biodiversity in the world, this can also be seen in the Culicidae family. However, there are a limited number of studies on this group. This work provides a baseline reference for this insect group and information about numerous potential and vector disease species. Species names and records were extracted from the National Mosquito Reference Collection at INSPI-Quito, published literature and web databases. The specimens at the INSPI collection were identified using morphological keys and, in a few cases, using molecular markers in the genus Anopheles. An updated list includes the subfamilies Culicinae and Anophelinae, eight tribes, 22 genera and 200 species. We present 18 species cataloged as new records for Ecuador represented in two subfamilies, 6 tribes and 9 genera. Taxonomic notes, geographical distribution and medical importance data for the species involved are provided. The updated list of Mosquitoes (Diptera: Culicidae) is a guide for researchers and health personnel when studying biodiversity, fauna, insect vectors and strategies to prevent the spread of vector diseases.

ecology↗

bioRxiv2020

Household-Level Risk Factors for Aedes aegypti Pupal Density in Guayaquil, Ecuador

BackgroundVector-borne diseases are a major cause of disease burden in Guayaquil, Ecuador, especially arboviruses spread by Aedes aegypti mosquitoes. Understanding which household characteristics and risk factors lead to higher Ae. aegypti densities and consequent disease risk can help inform and optimize vector control programs. MethodsCross-sectional entomological surveys were conducted in Guayaquil between 2013 and 2016, covering household demographics, municipal services, potential breeding containers, presence of Ae. aegypti larvae and pupae, and history of using mosquito control methods. A zero-truncated negative binomial regression model was fitted to data for estimating the household pupal index. An additional model assessed the factors of the most productive breeding sites across all of the households. ResultsOf surveyed households, 610 satisfied inclusion criteria. The final household-level model found that collection of large solid items (e.g., furniture and tires) and rainfall the week of and 2 weeks before collection were negatively correlated with average pupae per container, while bed canopy use, unemployment, container water volume, and the interaction between large solid collection and rainfall 2 weeks before the sampling event were positively correlated. Selection of these variables across other top candidate models with {Delta}AICc < 1 was robust, with the strongest effects from large solid collection and bed canopy use. The final container-level model explaining the characteristics of breeding sites found that contaminated water is positively correlated with Ae. aegypti pupae counts while breeding sites composed of car parts, furniture, sewerage parts, vases, ceramic material, glass material, metal material, and plastic material were all negatively correlated. ConclusionHaving access to municipal services like bulky item pickup was effective at reducing mosquito proliferation in households. Association of bed canopy use with higher mosquito densities is unexpected, and may be a consequence of large local mosquito populations or due to limited use or effectiveness of other vector control methods. The impact of rainfall on mosquito density is multifaceted, as it may both create new habitat and "wash out" existing habitat. Providing services and social/technical interventions focused on monitoring and eliminating productive breeding sites is important for reducing aquatic-stage mosquito densities in households at risk for Ae. aegypti-transmitted diseases.

ecology↗

bioRxiv2019

Genetic variation of Aedes aegypti populations from Ecuador

This is the first genetic analysis in Ecuador of Aedes aegypti using fragments of mitochondrial genes, NADH dehydrogenase subunit 4 (ND4) and cytochrome oxidase subunit I (COI). A total of 154 mosquitoes from 23 localities were collected in the Pacific coastal lowlands, Amazon basin lowlands, and the Galapagos Islands from 2012 to 2019. The analysis of fragments of the genes COI (672 bp) and ND4 (262 bp) and concatenated analysis of both COI and ND4 showed two haplotypes (H1, H2) present in Ecuador mainland and the Galapagos Islands. The phylogenetic analysis identified two well-supported clades. Combined analysis of both genes from ten localities also resulted in two haplotypes. Nucleotide diversity, neutrality tests (Tajimas test D, Fu and Lis F*and D*) and AMOVA analysis of the entire data set suggest balancing selection for both genes. The results indicate genetic variation without geographical restriction. COI-H1 grouped with sequences from the Americas, West and Central Africa, East Africa, Asia, and Australia. ND4-H1 grouped with similar sequences from the Americas, Asia and West Africa. COI-H2 grouped with sequences from Asia and the Americas. ND4-H2 grouped with sequences from the Americas. We report overlapping peaks in four sequences that suggest heteroplasmy in the individuals. The origin of the populations of Aedes aegypti in Ecuador show African genetic origin and are widely present in several countries in the Americas. One of the genetic variants is more common in all the localities and the two haplotypes are distributed indistinctly in the three geographical sampled areas in Ecuador.

genetics↗

bioRxiv2017

Metagenomic DNA sequencing for the diagnosis of intraocular infections

PurposeTo compare the performance of unbiased high-throughput sequencing with pathogen directed PCR using DNA isolated from archived ocular fluid, approaches that are compatible with the current sample handling practice of ophthalmologists.\n\nDesignRetrospective molecular study of banked vitreous samples.\n\nMethodsWe evaluated a metagenomic DNA sequencing-based approach (DNA-seq) using archived positive (n = 31) and negative (n=36) vitreous specimens as determined by reference pathogen-specific PCR assays (herpes simplex virus 1 and 2, cytomegalovirus, varicella-zoster virus, and Toxoplasma gondii). Pathogens were identified using a rapid computational pipeline to analyze the non-host sequences obtained from DNA-seq. Clinical samples were de-identified and laboratory personnel handling the samples and interpreting the data were masked.\n\nResultsMetagenomic DNA sequencing detected 87% of positive reference samples. In the presumed negative reference samples, DNA-seq detected an additional 6 different pathogens in 8 samples (22% of negative samples) that were either not detected or not targeted with pathogen-specific PCR assays. Infectious agents identified only with DNA-seq were Candida dubliniensis, Klebsiella pneumoniae, human herpesvirus 6 (HHV-6), and human T-cell leukemia virus type 1 (HTLV-1). Discordant samples were independently verified in CLIA-certified laboratories. CMV sequences were compared against the antiviral mutation database and 3 of the samples were found to have mutations conferring ganciclovir resistance.\n\nConclusionsMetagenomic DNA sequencing was highly concordant with pathogen-directed PCRs. The unbiased nature of metagenomics DNA sequencing allowed an expanded scope of pathogen detection, including bacteria, fungal species, and viruses, resolving 22% of cases that had previously escaped detection by routine pathogen-specific PCRs. The detection of drug resistance mutations highlights the potential for unbiased sequencing to provide clinically actionable information beyond pathogen species detection.

genomics↗