Browsing by Author "Villacis Salazar, Anita Gabriela"
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2b-RAD genotyping for population genomic studies of Chagas disease vectors: Rhodnius ecuadoriensis in Ecuador(2017) Costales Cordero, Jaime Alfredo; Ocaña Mayorga, Sofía Beatriz; Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Jaime Alfredo Costales Cordero, Sofía Beatriz Ocaña Mayorga, Anita Gabriela Villacis Salazar y César Alberto Yumiseva MarínRhodnius ecuadoriensis is the main triatomine vector of Chagas disease, American trypanosomiasis, in Southern Ecuador and Northern Peru. Genomic approaches and next generation sequencing technologies have become powerful tools for investigating population diversity and structure which is a key consideration for vector control. Here we assess the effectiveness of three different 2b restriction site-associated DNA (2b-RAD) genotyping strategies in R. ecuadoriensis to provide sufficient genomic resolution to tease apart microevolutionary processes and undertake some pilot population genomic analyses.Item Open Access Abundance, Natural Infection with Trypanosomes, and Food Source of an Endemic Species of Triatomine, Panstrongylus howardi (Neiva 1911), on the Ecuadorian Central Coast(2015) Baus Carrera, Esteban Guillermo; Grijalva Cobo, Mario Javier; Ocaña Mayorga, Sofía Beatriz; Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Grijalva Cobo, Mario JavierThe elimination of domestic triatomines is the foundation of Chagas disease control. Regional initiatives are eliminating introduced triatomine species. In this scenario, endemic triatomines can occupy the ecological niches left open and become a threat to long-term Chagas disease control efforts. This study determined the abundance, colonization, and Trypanosoma cruzi infection rate of the endemic Panstrongylus howardi in 10 rural communities located in Ecuador's Manabí Province. In total, 518 individuals of P. howardi were collected. Infestation indices of 1.4% and 6.6% were found in the domestic and peridomestic environments, respectively. We determined a T. cruzi infection rate of 53.2% (N = 47) in this species. P. howardi has a high capacity to adapt to different habitats, especially in the peridomicile. This implies a considerable risk of transmission because of the frequency of intradomicile invasion. Therefore, this species needs to be taken into account in Chagas control and surveillance efforts in the region.Item Open Access Bats, trypanosomes, and triatomines in Ecuador: new insights into the diversity, transmission, and origins of Trypanosoma cruzi and chagas disease(2015-10-14) Grijalva Cobo, Mario Javier; Ocaña Mayorga, Sofía Beatriz; Pinto Báez, Christian Miguel; Villacis Salazar, Anita Gabriela; Pinto Báez, Christian MiguelThe generalist parasite Trypanosoma cruzi has two phylogenetic lineages associated almost exclusively with bats—Trypanosoma cruzi Tcbat and the subspecies T. c. marinkellei. We present new information on the genetic variation, geographic distribution, host associations, and potential vectors of these lineages. We conducted field surveys of bats and triatomines in southern Ecuador, a country endemic for Chagas disease, and screened for trypanosomes by microscopy and PCR. We identified parasites at species and genotype levels through phylogenetic approaches based on 18S ribosomal RNA (18S rRNA) and cytochrome b (cytb) genes and conducted a comparison of nucleotide diversity of the cytb gene. We document for the first time T. cruzi Tcbat and T. c. marinkellei in Ecuador, expanding their distribution in South America to the western side of the Andes. In addition, we found the triatominesCavernicola pilosa and Triatoma dispar sharing shelters with bats. The comparisons of nucleotide diversity revealed a higher diversity for T. c. marinkellei than any of the T. c. cruzigenotypes associated with Chagas disease. Findings from this study increased both the number of host species and known geographical ranges of both parasites and suggest potential vectors for these two trypanosomes associated with bats in rural areas of southern Ecuador. The higher nucleotide diversity of T. c. marinkellei supports a long evolutionary relationship between T. cruzi and bats, implying that bats are the original hosts of this important parasite.Item Metadata only Chagas vectors Panstrongylus chinai (Del Ponte, 1929) and Panstrongylus howardi (Neiva, 1911): chromatic forms or true species?(2020-05-06) Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Villacis Salazar, Anita GabrielaBackground: Chagas disease is a parasitic infection transmitted by “kissing bugs” (Hemiptera: Reduviidae: Triatominae) that has a huge economic impact in Latin American countries. The vector species with the upmost epidemiological importance in Ecuador are Rhodnius ecuadoriensis (Lent & Leon, 1958) and Triatoma dimidiata (Latreille, 1811). However, other species such as Panstrongylus howardi (Neiva, 1911) and Panstrongylus chinai (Del Ponte, 1929) act as secondary vectors due to their growing adaptation to domestic structures and their ability to transmit the parasite to humans. The latter two taxa are distributed in two different regions, they are allopatric and differ mainly by their general color. Their relative morphological similarity led some authors to suspect that P. chinai is a melanic form of P. howardi. Methods: The present study explored this question using different approaches: antennal phenotype; geometric morphometrics of heads, wings and eggs; cytogenetics; molecular genetics; experimental crosses; and ecological niche modeling. Results: The antennal morphology, geometric morphometrics of head and wing shape and cytogenetic analysis were unable to show distinct differences between the two taxa. However, geometric morphometrics of the eggs, molecular genetics, ecological niche modeling and experimental crosses including chromosomal analyses of the F1 hybrids, in addition to their coloration and current distribution support the hypothesis that P. chinai and P. howardi are separate species. Conclusions: Based on the evidence provided here, P. howardi and P. chinai should not be synonymized. They represent two valid, closely related species.Item Metadata only La ciencia en el control y la prevención de las enfermedades desatendidas: los triatominos y la Enfermedad de ChagasVillacis Salazar, Anita GabrielaEl presente libro reúne los resúmenes de todas las charlas presentadas, revisados por un comité científico conformado por jóvenes que están cambiando al país con su esfuerzo por mostrar a la ciencia como una alternativa de vida, que, en momentos difíciles como este, es el camino para que la humanidad señale nuevas metas, enfocándose en el desarrollo de la investigación en todos sus ámbitos. El evento y el libro de memorias recoge las ponencias de los participantes que sumaron 114 asistentes, seis charlas magistrales y 60 ponentes de prestigiosas instituciones nacionales y extranjeras como son: Universidad UTE, ESPOL, IKIAM, INABIO, INIAP, INSPI-LIP, PUCE, UCE, UDLA, UIDE, UG, UTM, Yachay Tech, Max-Planck-Institute of Molecular Cell Biology and Genetics, Universidad de Helsinki, Universidad de Córdoba, Universidad de Sevilla, Universidad de la Serena, Universidad Austral de Chile y la Universidad de Barcelona.Item Metadata only Detección de la presencia de insectos transmisores de la enfermedad de chagas mediante la técnica de eficacia de búsqueda manual. ¿será o no un beneficio para las comunidades rurales?Moncayo Benalcázar, Ana Lucía; Ocaña Mayorga, Sofía Beatriz; Villacis Salazar, Anita Gabriela; Yumiseva Marín, César AlbertoEl Centro de Investigación en Enfermedades Infecciosas y Crónicas (CIEIC) organiza el “IV Encuentro Internacional de Investigación en Enfermedades Infecciosas y Medicina Tropical”, del 13 al 15 de Junio, en la Pontificia Universidad Católica del Ecuador (PUCE), en Quito. El objetivo de este congreso es reunir a la comunidad científica para impulsar y generar la oportunidad de crear redes colaborativas entre las distintas instituciones que trabajan en investigación de enfermedades infecciosas.Item Metadata only Determinants of intentions to prevent triatomine infestation based on the health belief model: An application in rural southern Ecuador(2020) Villacis Salazar, Anita Gabriela; Villacis Salazar, Anita GabrielaIntroduction: Control of triatomine infestation is a key strategy for the prevention of Chagas disease (CD). To promote this strategy, it is important to know which antecedents to behavioral change are the best to emphasize when promoting prevention. Objective: The aim of this study was to determine predictors for intention to prevent home infestation based on the Health Belief Model (HBM), a commonly used health intervention planning theory. Materials & methods: A cross-sectional study was conducted with 112 heads of household in six communities with endemic and high rates of triatomine infestation in Loja province, Ecuador. The data was collected by a questionnaire including perceived severity, susceptibility, benefits to action, barriers to action, and self-efficacy. These data were also used to predict actual infestation of homes. Results: Community members reported strong intentions to prevent home infestation. HBM constructs predicted about 14% of the observed variance in intentions. Perceived susceptibility and severity did not predict behavioral intention well; perceived barriers to small-scale action that reduce likelihood of infestation and self-efficacy in participating in surveillance systems did. Self-efficacy and perception of barriers were equally powerful predictors. The HBM constructs, however, did not predict well actual infestation. Conclusion: The findings supported the HBM as a way to predict intentions to prevent infestation of the home by triatomine bugs. The findings highlight that messages emphasizing self-efficacy in participating in surveillance systems and overcoming barriers to small-scale action that reduce likelihood of infestation, rather than a focus on risk, should be central messages when designing and implementing educational interventions for CD. The gap between behavioral intention and actual infestation reveals the need to assess home practices and their actual efficacy to fully enact and apply the HBM.Item Metadata only Diseño y desarrollo de un videojuego Educativo mediante una metodología ágil, como herramienta orientada a niños de 7 a 11 años para la prevención de la enfermedad de Chagas(2020) Rodríguez Clavijo, Francisco; Villacis Salazar, Anita Gabriela; Rodríguez Clavijo, FranciscoChagas disease (CD) is caused by Trypanosoma cruzi and transmitted by the feces of Triatomine insects. The absence of treatments and effective vaccines makes this disease not only a medical problem, but also an educational, social and psychological problem. Education appears as an important axis of research for the prevention of this disease. For this reason, we proposed the design and develop of a videogame for children, as an educational tool to raise awareness about CD in vulnerable areas of Ecuador. The videogame design was focused on the risk factors of the CD, and under the guidelines of a Game Document Design, and it’s development was based on the agile Scrum methodology, that was structured in sprints; and the Unity videogame engine. Nielsen heuristics was applied to perform usability tests on children from 7 to 11 years old. Finally, the video game is ready to be used and broadcast the message for CD prevention in the rural communities of Manabí, Ecuador.Item Metadata only Distribución potencial de triatominos vectores de la enfermedad de Chagas en la comunidad de patas yacu, amazonía ecuatorianaVillacis Salazar, Anita Gabriela; Yumiseva Marín, César AlbertoLa Escuela Superior Politécnica del Litoral, impulsando la sociedad del conocimiento, mediante la Facultad de Ciencias de la Vida encargada de organizar las cuadragésimas XL Jornadas Nacionales de Biología, evento promocionado por la Sociedad Ecuatoriana de Biología y que se constituye como el más importante espacio para la difusión de la investigación e innovación en el área de las Ciencias de la Vida; a realizarse desde el 16 al 18 de noviembre de 2016 en el Campus Prosperina de la ESPOL, en el Auditorio del Centro de Información Bibliotecario y cuenta con la participación de investigadores nacionales e internaciones en las temáticas antes escritas, con el horario de 09h00 hasta las 18h00. Evento trascendental de actualización y fortalecimiento científico que reúne anualmente a científicos, profesionales y estudiantes del área de las ciencias biológicas y ciencias afines de todas las universidades del país en un espacio de integración, diálogo y divulgación de resultados de investigación.Item Metadata only Distribution of triatomine species in domestic and peridomestic environments in central coastal Ecuador(2017) Baus Carrera, Esteban Guillermo; Grijalva Cobo, Mario Javier; Moncayo Benalcázar, Ana Lucía; Ocaña Mayorga, Sofía Beatriz; Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Baus Carrera, Esteban GuillermoBackground: Although the central coast of the Ecuador is considered endemic for Chagas disease, few studies have focused on determining the risk of transmission in this region. In this study we describe the triatomine household infestation in Manabí province (Central Coast region), determine the rate of Trypanosoma cruzi infection and study the risk factors associated with infestation by Rhodnius ecuadoriensis. Methodology/principal findings: An entomological survey found three triatomine species (Rhodnius ecuadoriensis, Panstrongylus rufotuberculatus and P. howardi) infesting domiciles in 47.4% of the 78 communities visited (total infestation rate of 4.5%). Four percent of domiciles were infested, and nymphs were observed in 77% of those domiciles. The three species were found in altitudes below 500 masl and in all ecological zones except cloud forest. Within the domicile, we found the three species mostly in bedrooms. Rhodnius ecuadoriensis and P. rufotuberculatus were abundant in bird nests, including chicken coops and P. howardi associated with rats in piles of bricks, in the peridomicile. Triatomine infestation was characterized by high rates of colonization, especially in peridomicile. Flagelates infection was detected in only 12% of the samples by microscopy and Trypanosoma cruzi infection in 42% of the examined triatomines by PCR (n = 372). The most important risk factors for house infestation by R. ecuadoriensis were ecological zone (w = 0.99) and presence of chickens (w = 0.96). Determinants of secondary importance were reporting no insecticide applications over the last twelve months (w = 0.86) and dirt floor (w = 0.70). On the other hand, wood as wall material was a protective factor (w = 0.85). Conclusion/significance: According the results, approximately 571,000 people would be at high risk for T. cruzi infection in Manabí province. A multidisciplinary approximation and the adhesion to a periodic integrated vector management (IVM) program are essential to guarantee sustainable preventive and control strategies for Chagas disease in this region.Item Metadata only Ecosalud en las enfermedades transmitidas por vectores: chagas, dengue y malaria(2018-05) Neira Oviedo, Marco Vinicio; Sáenz Calderón, Fabián Ernesto; Villacis Salazar, Anita Gabriela; Arteaga, E., Aguilar, H., Breilh, J. y Campaña, M.La Medicina Ecuatoriana en el siglo XXI es una colección de tres tomos dedicados a: Clínica y diagnóstico, Cirugía e intervencionismo, y las Ciencias en la salud colectiva y terapias integrativas. La colección es un esfuerzo científico y editorial inédito en el país. Cuenta con el trabajo de 177 especialistas ecuatorianos. Los tomos recogen 450 cuadros, figuras y fotografías. Más de 1200 páginas distribuidas en 55 capítulos especializados.Item Metadata only Genetic data support speciation between Panstrongylus howardi and Panstrongylus chinai, vectors of Chagas disease in Ecuador(2020-03) Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Villacis Salazar, Anita GabrielaLimited genetic data are currently available for three vectors of Chagas disease in Ecuador, Panstrongylus howardi, P. chinai, and P. rufotuberculatus. Previously regarded as mainly sylvatic, these species have been poorly studied. Recently, they have been more frequently reported in domiciles and peridomiciles and are now considered true secondary vectors of Chagas disease in a country where an estimated 200,000 people are infected by Trypanosoma cruzi, a causative agent of this disease. In order to fill this gap, we obtained DNA for sequencing from 53 insects belonging to these three species and mainly sampled from the two Ecuadorian provinces of Loja and Manabí. We used six mitochondrial loci (COI, COII, ND4, CytB, 16S, and 12S) and two nuclear ones (ITS2 and 18S). We interpreted the phylogenetic trees built with single and concatenated data through maximum likelihood, Bayesian Markov chain Monte Carlo, and maximum parsimony methods. We provide evidence that P. chinai and P. howardi are indeed two supported species closely related and derived from a common ancestor. Additionally, the phylogenetic position of P. rufotuberculatus was confirmed as being distant from P. chinai and P. howardi and clustered with Triatoma dimidiata, a species belonging to the Northern American Triatoma clade.Item Metadata only Influence of ecological factors on the presence of a triatomine species associated with the arboreal habitat of a host of Trypanosoma cruzi(2018) Crespo Pérez, María Verónica; Grijalva Cobo, Mario Javier; Ocaña Mayorga, Sofía Beatriz; Pinto Báez, Christian Miguel; Villacis Salazar, Anita Gabriela; Crespo Pérez, María VerónicaBackground: The white-naped squirrel, Simosciurus nebouxii (previously known as Sciurus stramineus), has recently been identified as an important natural host for Trypanosoma cruzi in Ecuador. The nests of this species have been reported as having high infestation rates with the triatomine vector Rhodnius ecuadoriensis. The present study aims to determine the levels of nest infestation with R. ecuadoriensis, the ecological variables that are influencing the nest site selection, and the relationship between R. ecuadoriensis infestation and trypanosome infection. Results: The study was carried out in transects in forest patches near two rural communities in southern Ecuador. We recorded ecological information of the trees that harbored squirrel nests and the trees within a 10 m radius. Manual examinations of each nest determined infestation with triatomines. We recorded 498 trees (n = 52 with nests and n = 446 without nests). Rhodnius ecuadoriensis was present in 59.5% of the nests and 60% presented infestation with nymphs (colonization). Moreover, we detected T. cruzi in 46% of the triatomines analyzed. Conclusions: We observed that tree height influences nest site selection, which is consistent with previous observations of squirrel species. Factors such as the diameter at breast height and the interaction between tree height and tree species were not sufficient to explain squirrel nest presence or absence. However, the nest occupancy and tree richness around the nest were significant predictors of the abundance of triatomines. Nevertheless, the variables of colonization and infection were not significant, and the data observed could be expected because of chance alone (under the null hypothesis). This study ratifies the hypothesis that the ecological features of the forest patches around rural communities in southern Ecuador favor the presence of nesting areas for S. nebouxii and an increase of the chances of having triatomines that maintain T. cruzi populations circulating in areas near human dwellings. Additionally, these results highlight the importance of including ecological studies to understand the dynamics of T. cruzi transmission due to the existence of similar ecological and land use features along the distribution of the dry forest of southern Ecuador and northern Peru, which implies similar challenges for Chagas disease control.Item Metadata only Life cycle, feeding, and defecation patterns of Panstrongylus chinai (Hemiptera: Reduviidae: Triatominae) under laboratory conditions(2016-07) Villacis Salazar, Anita Gabriela; Grijalva Cobo, Mario Javier; Villacis Salazar, Anita GabrielaChagas disease is caused by the protozoan Trypanosoma cruzi. Panstrongylus chinai (Del Ponte) is highly domiciliated in the Peruvian and Ecuadorian Andes and has been found naturally infected with T. cruzi. The objective of this study was to describe the life cycle, feeding, and defecation patterns of P. chinai in the Loja province within southern Ecuador. To characterize its life cycle, a cohort of 70 individuals was followed from egg to adult. At each stage of development, prefeeding time, feeding time, weight of ingested meal, proportional weight increase, and the time to the first defecation were recorded. Panstrongylus chinai completed its development in 371.4 ± 22.3 d, (95% CI 355.4–387.4), which means that it is likely a univoltine species. Prefeeding time, feeding time, and weight of ingested meal increased as individuals developed through nymphal stages. Moreover, time to first defecation was shortest in the early nymphal stages, suggesting higher vector potential in the early developmental stages. Data obtained in this study represent an important advance in our knowledge of the biology of P. chinai, which should be considered as a secondary Chagas disease vector species in the Andean valleys of Loja (Ecuador) and in the north of Peru, and included in entomological surveillance programs.Item Metadata only Life cycle, feeding, and defecation patterns of Triatoma carrioni (Hemiptera: Reduviidae), under laboratory conditions(2019-04) Grijalva Cobo, Mario Javier; Moncayo Benalcázar, Ana Lucía; Villacis Salazar, Anita Gabriela; Grijalva Cobo, Mario JavierChagas disease is caused by Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae). It is transmitted to humans primarily through contaminated feces of blood-sucking vectors of the subfamily Triatominae, known in Ecuador as 'chinchorros'. Some Triatominae species can adapt to domiciliary and peridomiciliary environments where T. cruzi can be transmitted to humans. Triatoma carrioni (Larrousse 1926) colonizes domestic and peridomestic habitats up to 2,242 m above sea level (masl) in southern Ecuador (Loja Province) and northern Peru. This study describes the life cycle, feeding, and defecation patterns of T. carrioni under controlled laboratory conditions using mice as hosts. Specimens were collected in Loja Province, Ecuador, and maintained in the laboratory. The life cycle was approximately 385.7 ± 110.6 d. There was a high mortality rate, 40.9% for first instars and 38.9% for fifth instars (NV). Feeding and defecation patterns for each life stage were examined by recording: insertion time of the proboscis into the host, total feeding time, time to first defecation, and weight of the bloodmeal. Total feeding time varied between 20.6 ± 11.4 min for first instars (NI) and 48.9 ± 19.0 min for adult females. The time to first defecation was variable but ranged from 9.8 ± 10.6 min for NI to 39.4 ± 24.7 min for NV during feeding. This suggests that T. carrioni has an annual life cycle and is a potential vector of T. cruzi in Loja Province. Improved knowledge of populations of T. carrioni in domestic and peridomestic environments of Ecuador can have a significant impact on the prevention and control of Chagas disease.Item Metadata only Molecular data supports monophyly of Triatoma dispar complex within genus Triatoma(2020-11) Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Villacis Salazar, Anita GabrielaThe genus Triatoma contains numerous species, principal or secondary vectors of Chagas disease, which have been included in the three main lineages of Triatomini tribe based on morphological and biogeographical characteristics: North American, South American, and T. dispar complex. The three members of the T. dispar complex are distributed in Ecuador. This complex has been scarcely studied through molecular approaches, and the taxonomic position of this complex is not confirmed. In this study, we explored the phylogenetic relationships within the genus Triatoma, including five species from North and Central America, six from South America, and the three species belonging to the T. dispar complex. Partial sequences of four mitochondrial genes (Cyt b, COII, 16S-rRNA, 12S-rRNA) and two nuclear genes (18S-rRNA, ITS2) were obtained from 74 specimens. Phylogenetic trees were built with concatenated and single sequences through maximum likelihood (ML), maximum parsimony (MP), and Bayesian methods. The trees built using concatenated sequences showed three main branches (clusters) highly supported by significant bootstrap values; the T. dispar complex appeared as a monophyletic group separate from species of North and Central American origin and South American origin. On the contrary, for each gene tree, the three main clusters were not always significantly supported, mostly because genetic information is dramatically reduced when a single gene is considered. Consequently, concatenation of genes gives relevant results and is highly recommended for further in-depth examination of the relationships of several species and complexes of triatomines that remain unresolved. Moreover, our current molecular data fully revealed the division of genus Triatoma into at least three main genetic groups.Item Metadata only Pioneer study of population genetics of Rhodnius ecuadoriensis (Hemiptera: Reduviidae) from the central coastand southern Andean regions of Ecuador(2017-09) Grijalva Cobo, Mario Javier; Villacis Salazar, Anita Gabriela; Yumiseva Marín, César Alberto; Grijalva Cobo, Mario JavierEffective control of Chagas disease vector populations requires a good understanding of the epidemiological components, including a reliable analysis of the genetic structure of vector populations. Rhodnius ecuadoriensis is the most widespread vector of Chagas disease in Ecuador, occupying domestic, peridomestic and sylvatic habitats. It is widely distributed in the central coast and southern highlands regions of Ecuador, two very different regions in terms of bio-geographical characteristics. To evaluate the genetic relationship among R. ecuadoriensis populations in these two regions, we analyzed genetic variability at two microsatellite loci for 326 specimens (n = 122 in Manabí and n = 204 in Loja) and the mitochondrial cytochrome b gene (Cyt b) sequences for 174 individuals collected in the two provinces (n = 73 and = 101 in Manabí and Loja respectively). The individual samples were grouped in populations according to their community of origin. A few populations presented positive FIS, possible due to Wahlund effect. Significant pairwise differentiation was detected between populations within each province for both genetic markers, and the isolation by distance model was significant for these populations. Microsatellite markers showed significant genetic differentiation between the populations of the two provinces. The partial sequences of the Cyt b gene (578 bp) identified a total of 34 haplotypes among 174 specimens sequenced, which translated into high haplotype diversity (Hd = 0.929). The haplotype distribution differed among provinces (significant Fisher's exact test). Overall, the genetic differentiation of R. ecuadoriensis between provinces detected in this study is consistent with the biological and phenotypic differences previously observed between Manabí and Loja populations. The current phylogenetic analysis evidenced the monophyly of the populations of R. ecuadoriensis within the R. pallescens species complex; R. pallescens and R. colombiensis were more closely related than they were to R. ecuadoriensis.Item Metadata only Triatominae: does the shape change of non-viable eggs compromise species recognition?(2018-10-10) Grijalva Cobo, Mario Javier; Villacis Salazar, Anita Gabriela; Grijalva Cobo, Mario JavierEggs have epidemiological and taxonomic importance in the subfamily Triatominae, which contains Chagas disease vectors. The metric properties (size and shape) of eggs are useful for distinguishing between close species, or different geographical populations of the same species.Item Open Access Trypanosoma cruzi population dynamics in the Central Ecuadorian Coast.(2015) Costales Cordero, Jaime Alfredo; Grijalva Cobo, Mario Javier; Villacis Salazar, Anita Gabriela; Ocaña Mayorga, Sofía Beatriz; Grijalva Cobo, Mario JaviertChagas disease is the most important parasitic disease in Latin America. The causative agent, Trypanosomacruzi, displays high genetic diversity and circulates in complex transmission cycles among domestic,peridomestic and sylvatic environments. In Ecuador, Rhodnius ecuadoriensis is known to be the majorvector species implicated in T. cruzi transmission. However, across vast areas of Ecuador, little is knownabout T. cruzi genetic diversity in relation to different parasite transmission scenarios.Fifty-eight T. cruzi stocks from the central Ecuadorian coast, most of them derived from R. ecuadorien-sis, were included in the study. All of them were genotyped as T. cruzi discrete typing unit I (DTU TcI).Analysis of 23 polymorphic microsatellite loci through neighbor joining and discriminant analysis ofprincipal components yielded broadly congruent results and indicate genetic subdivision between syl-vatic and peridomestic transmission cycles. However, both analyses also suggest that any barriers areimperfect and significant gene flow between parasite subpopulations in different habitats exists. Alsoconsistent with moderate partition and residual gene flow between subpopulations, the fixation index(FST) was significant, but of low magnitude. Finally, the lack of private alleles in the domestic/peridomestictransmission cycle suggests the sylvatic strains constitute the ancestral population.The T. cruzi population in the central Ecuadorian coast shows moderate tendency to subdivision accord-ing to transmission cycle. However, connectivity between cycles exists and the sylvatic T. cruzi populationharbored by R. ecuadoriensis vectors appears to constitute a source from which the parasite invades humandomiciles and their surroundings in this region. We discuss the implications these findings have for theplanning, implementation and evaluation of local Chagas disease control interventions.Item Metadata only Vector transmission: How it works, what transmits, where it occurs(2017) Villacis Salazar, Anita Gabriela; Villacis Salazar, Anita GabrielaVector transmission remains the main mode of Chagas disease transmission. The first part of this chapter presents the current state of knowledge on the transmission mechanisms, the factors that attract bugs to their prey, how bug saliva helps feeding, and several milestones to understand how the parasite invades a wide variety of vertebrate cells. The second part examines vector species and the properties that make them efficient vectors. Then we focus on wild eclectic species that participate in new Chagas transmission scenarios, most particularly in the Amazon region. The third part discusses where transmission can occur, usually in dwellings: the vectors live in homes or transiently invade them. Several studies aiming to identify the associated factors are reviewed, but we also discuss the possible transmission outside dwellings. The last part discusses the inhabitants’ perception and knowledge of vectors, showing how education of the inhabitants of endemic countries is needed to fight vector transmission.