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Vector-Borne Diseases Transmission in Ecuador: Implication of Vertebrate Hosts as Food Source of Triatomines in Chagas Disease, and the Diversity of Anopheles Mosquites in Malaria

Ocana Mayorga, Sofia Beatriz
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1579196385136684

Abstract Details

2020, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).
Malaria and Chagas disease are two of the most important vector-borne parasitic infections in Ecuador. A better understanding on the transmission scenarios is needed to propose effective strategies for disease control. In Chagas disease, human-vector dynamics is not well understood; however, the presence of active transmission in endemic areas has been demonstrated. The pattern of blood meals of insects that are vector of diseases is fundamental to unveil transmission dynamics. In this study DNA from intestinal contents of triatomines were used to amplify fragments of cytb mitochondrial genes. The results showed that humans are a main source of food for triatomines, indicating that the vector-human contact is more frequent than previously thought. Although other groups of mammals such as rodents are also an available source of blood, birds (particularly chickens) might have a predominant role in the maintenance of triatomines in these areas. The presence of human blood meal in 42% of the samples, even in peridomiciliar and sylvatic environments, together with high infection rates with Trypanosoma cruzi (the causal agent of Chagas disease) indicate that humans are not accidental host, but an important source of blood for triatomines in all environments, and with high risk of T. cruzi transmission. Consequently, domestic-centered strategies might not prevent vectorial transmission and data of Chagas disease cases might be underestimated. Strategies for Chagas disease control in Ecuador require to evaluate capacity dispersal of triatomines and outdoor activities as risk factors for parasite transmission in Ecuador. In the case of malaria, the lack of a complete inventory of vector species is a barrier for an understanding of malaria transmission. Even more, implication on transmission of reported species is still poorly understood. Identification of species is mainly carried out by morphological characteristics; however, it fails in discriminating species closely related. Molecular tools are a good alternative to discriminate species. In this study, the internal transcribed spacer 2 (ITS2) and the cytochrome oxidase I (COI), were used for species identification. The Restriction Fragment Length Polymorphism (RFLP) of the ITS2 is a technique that allows the analysis of a great amount of samples and it is cheaper than sequencing. However, variability within species and populations needs to be further known. The results demonstrated the great complexity of taxonomic identification of species, particularly of individuals from species complex, such as the case of the Oswaldoi group which species are sympathric in the Amazon region. In Ecuador, particularly, in the Amazon region we recommend the sequence of COI for anopheline identification until a better knowledge of the diversity is obtained. This study confirmed Ny. albimanus as the most abundant species in the Pacific coast and it also extends the geographic distribution of An. calderoni. In the Amazon region, Ny. benarrochi B is reported for first time in the Ecuadorian Amazon. A comprehensive survey of Anopheles and Nyssorhynchus species in Ecuador is required to facilitate and targeted malaria control strategies in Ecuador.
Mario Grijalva, Ph.D. (Advisor)
Sarah Wyatt, Ph.D. (Committee Member)
Calvin James, Ph.D. (Committee Member)
Janet Duerr, Ph.D. (Committee Member)
Daewoo Lee, Ph.D. (Committee Chair)
220 p.
Biology; Biomedical Research; Entomology
Chagas disease; Malaria; triatomines; anophelines; Ecuador; disease transmission

Recommended Citations

Citations

  • Ocana Mayorga, S. B. (2020). Vector-Borne Diseases Transmission in Ecuador: Implication of Vertebrate Hosts as Food Source of Triatomines in Chagas Disease, and the Diversity of Anopheles Mosquites in Malaria [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1579196385136684

    APA Style (7th edition)

  • Ocana Mayorga, Sofia . Vector-Borne Diseases Transmission in Ecuador: Implication of Vertebrate Hosts as Food Source of Triatomines in Chagas Disease, and the Diversity of Anopheles Mosquites in Malaria . 2020. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1579196385136684.

    MLA Style (8th edition)

  • Ocana Mayorga, Sofia . "Vector-Borne Diseases Transmission in Ecuador: Implication of Vertebrate Hosts as Food Source of Triatomines in Chagas Disease, and the Diversity of Anopheles Mosquites in Malaria ." Doctoral dissertation, Ohio University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1579196385136684

    Chicago Manual of Style (17th edition)

ohiou1579196385136684
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This open access ETD is published by Ohio University and OhioLINK.