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Free Content Chromosomal variation and genome size support existence of cryptic species of Triatoma dimidiata with different epidemiological importance as Chagas disease vectors

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The wide geographical distribution of Triatoma dimidiata, one of the three major vectors of Chagas disease, ranges from Mexico to northern Peru. Since this species occupies a great diversity of artificial and natural ecotopes, its eradication is extremely difficult. In order to assist control efforts, we used chromosome analyses and DNA amount as taxonomic markers to study genetic variability in populations of T. dimidiata from Mexico, Guatemala, El Salvador and Colombia. We differentiated three groups or cytotypes defined by characteristic chromosome C-banding patterns and genome size measured by flow cytometry. The three cytotypes are restricted to different geographic locations. Cytotype 1 occurs in Mexico (excluding Yucatán), Guatemala (excluding Petén), El Salvador and Colombia. Cytotype 2 occurs in Yucatán and cytotype 3 occurs in Petén. Cytotype 1, commonly associated with domestic and peridomestic environments but also inhabiting sylvatic ecotopes, is the most widespread and with major epidemiological significance. In contrast, the Yucatán cytotype inhabits wild ecotopes but increasingly enters houses, while the Petén cytotype appears exclusively sylvatic. We suggest that these cytotypes represent cryptic species of T. dimidiata with different epidemiological relevance as Chagas disease vectors. Poor ability to colonize human dwellings, together with their restricted geographic distribution, indicate that the Yucatán and Petén putative species probably have much less epidemiological significance than cytotype 1. Thus, the genetic markers we describe are powerful tools to differentiate cryptic species in T. dimidiata with different epidemiological significance, contributing to planning the most effective control measures.

Keywords: Chagas disease; Triatoma; chromosome variation; genome size

Document Type: Research Article


Affiliations: 1:  CISEI, Instituto Nacional de Salud Pública. Cuernavaca, Morelos, Mexico 2:  Facultad de Medicina, Universidad Nacional Autónoma de México, México DF, Mexico 3:  Escuela de Biología, Universidad de San Carlos, Ciudad de Guatemala, Guatemala 4:  Facultad de Farmacia, Universidad de Valencia, Valencia, Spain 5:  Laboratorio de Citómica, Centro de Investigación Príncipe Felipe, Valencia, Spain 6:  Centro de Investigaciones en Enfermedades Tropicales, Universidad Industrial de Santander, Piedecuesta, Colombia 7:  Grupo Chagas. Instituto de Biología, Universidad de Antioquia, Medellín, Colombia 8:  Center for Health Studies, Universidad del Valle de Guatemala. Guatemala 9:  Centro de Investigación y Desarrollo en Salud, Universidad de El Salvador, San Salvador 10:  Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay

Publication date: 2006-07-01

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