Document Type

Thesis

Date of Degree Completion

Fall 2016

Degree Name

Master of Science (MS)

Department

Biology

Committee Chair

Gabrielle Stryker

Second Committee Member

Blaise Dondji

Third Committee Member

Daniel Beck

Fourth Committee Member

Holly Pinkart

Abstract

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, which is transmitted to domestic and sylvatic mammals via the feces of hematophagous hemiptera of the subfamily Triatominae (Reduviidae). Trypanosoma cruzi is found only in the Americas and displays remarkable genetic diversity. Seven discrete typing units (DTUs) are currently recognized (TcI–TcVI and TcBat). In Jalisco, Mexico, where Chagas disease has a high prevalence rate, TcI has historically been the only DTU reported. This study focused on the molecular identification of T. cruzi DTUs circulating in Triatoma near the Estación de Biología Chamela, on the southwest coast of Jalisco, Mexico. I collected DNA from 95 Triatoma bugs. Trypanosoma cruzi infection was detected using PCR primers specific for the minicircle variable region of the parasite’s kinetoplast DNA (kDNA). Trypanosoma cruzi DTUs were identified by amplifying the intergenic region of the mini-exon, and the genes 24Sα, 18S, TcSC5D, and TcMK. Two species of Triatoma were collected, Triatoma longipennis and T. bolivari, with an overall infection rate of 59%. There was high genetic diversity of T. cruzi in my samples, with the DTUs TcI, TcII, TcIV, TcVI, and Tcbat being identified. This is the first report of TcVI and Tcbat in North America. In the Triatoma found to be infected, 96% had TcI, 35% TcII, 2% TcIV, 25% TcVI, and 2% Tcbat. Several vertebrate hosts for Triatoma were also identified from visible blood within Triatominaes’ gut using PCR primers for cytochrome b and cytochrome oxidase subunit I genes. My observations indicate a much higher diversity of T. cruzi DTUs in Triatoma than previously reported in Jalisco. The results have important implications for understanding the geographical distribution of T. cruzi DTUs and epidemiology of Chagas disease in Mexico.

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