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¡SOBRE México!: Student Opportunities for Biological Research in Mexico

Kissing Bugs (Triatoma) and Chagas Disease

Team Triatoma

 

Dr. Gabe Stryker, Biology Professor and Parasitologist, CWU

Dr. Victor Manuel Sanchez Cordero, Director, Instituto de Biología de México, Universidad Nacional Autonoma de Mexico

Uyen Nguyen, Graduate Student, CWU

Project Information: We are investigating the host-parasite relationships between Triatoma spp., the Trypanosomes they transmit, and the mammals that serve as hosts.  Triatoma (Reduviidae: Triatominae), are blood sucking insects that transmit the single-celled parasite Trypanosoma cruzi (Kinetoplastida, Trypanosomatidae), which infects mammals, including humans, throughout much of Latin America. T. cruzi, causes Chagas disease, which currently infects 6 - 7 million people. Chagas disease was already present in the Americas when humans arrived more than 10,000 years ago, but the Triatoma vectors have become domesticated in some rural environments where transmission occurs between humans and their domestic animals.  Triatoma often share shelter with the animals they feed on at night.  Triatoma are found throughout seasonally dry tropical forest in the Americas and, at the Chamela field station, are often captured in pitfall traps and seen on the station building walls.  These abundant insects offer a unique opportunity for students to use both field techniques and molecular biology to elucidate which vertebrates are serving as hosts and which strains of T. cruzi are circulating in Chamela.  PCR, sequence analysis, and bioinformatics will be used to identify the strains of T. cruzi found in the Triatoma, as part of an ongoing collaboration between Dr. Sánchez-Cordero of UNAM and Dr. Stryker of CWU. This study is investigating if the stains of T. cruzi in the forest are the same strains circulating within domestic settings, or if the wild and domestic cycles are separate.

Molecular techniques (Polymerase chain reaction or PCR) also allows for identification of which vertebrates Triatoma have been feeding on in the forest.  This can be examined directly using PCR and sequence analysis of Triatoma gut contents to identify vertebrate DNA in recently fed insects.  It can also be measured indirectly by testing tissues from small mammals trapped at the station for the presence of trypanosomes.  Students will also be able to trap small mammals and attach trail spools to locate nest sites to search for Triatoma congregations.  These studies will provide valuable information on which species of Triatoma are associated with which vertebrates in the region.

Examples of specific projects include:

  • Collect and analyze Triatoma gut contents to identify T. cruzi genotypes in Chamela.
  • Analyze recently fed Triatoma specimens for presence of host DNA to identify source of blood meal and potential T. cruzi reservoirs. 
  • Capture small mammals and attach trail spools to locate nest sites to search for Triatoma congregations.
  • Test tissue samples from small mammals using PCR to identify potential forest hosts of T. cruzi.
  • Collect, catalog and map all species of Triatoma encountered in the study area.
  • Investigate Triatoma life cycles and seasonal patterns of dispersal, migration, and habitat use within the study area.

Triatoma @ EBCh:

Two species of Triatoma have been found at the biological station in Chamela.

 

 

 Triatoma longipennis
81% infected

Triatoma dimidiata
44% infected

 

Some of the potential mammalian hosts of T. cruzi around EBCh:

 

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