The Prevalence of Trypanosoma cruzi, the Causal Agent of Chagas Disease, in Texas Rodent Populations

Adriana Aleman, Trina Guerra, Troy J. Maikis, Matthew T. Milholland, Ivan Castro-Arellano, Michael R. J. Forstner, Dittmar Hahn

Rodent species were assessed as potential hosts of Trypanosoma cruzi, the etiologic agent of Chagas disease, from five sites throughout Texas in sylvan and disturbed habitats. A total of 592 rodents were captured, resulting in a wide taxonomic representation of 11 genera and 15 species. Heart samples of 543 individuals were successfully analyzed by SybrGreen-based quantitative PCR (qPCR) targeting a 166 bp fragment of satellite DNA of T. cruzi. Eight rodents representing six species from six genera and two families were infected with T. cruzi. This is the first report of T. cruzi in the pygmy mouse (Baiomys taylori) and the white-footed mouse (Peromyscus leucopus) for the USA. All infected rodents were from the southernmost site (Las Palomas Wildlife Management Area). No differences in pathogen prevalence existed between disturbed habitats (5 of 131 tested; 3.8%) and sylvan habitats (3 of 40 tested; 7.5%). Most positives (n = 6, 16% prevalence) were detected in late winter with single positives in both spring (3% prevalence) and fall (1% prevalence). Additionally, 30 Triatoma insects were collected opportunistically from sites in central Texas. Fifty percent of these insects, i.e., 13 T. gerstaeckeri (68%), and two T. lecticularia (100%) were positive for T. cruzi. Comparative sequence analyses of 18S rRNA of samples provided identical results with respect to detection of the presence or absence of T. cruzi and assigned T. cruzi from rodents collected in late winter to lineage TcI. T. cruzi from Triatoma sp. and rodents from subsequent collections in spring and fall were different, however, and could not be assigned to other lineages with certainty.