Trypanosoma cruzi Prevalence in Mesomammals in South Texas: Is There a Host Sex-Bias?

Abstract

American trypanosomiasis, also known as Chagas disease, is caused by the protozoan Trypanosoma cruzi (T. cruzi). American trypanosomiasis is considered a neglected tropical disease which can cause serious cardiac and digestive problems in humans and other mammalian species. The only T. cruzi trypanosome vectors are invertebrate insects of the subfamily Triatominae. Most species of triatomines are associated with free-ranging vertebrates which act as reservoir hosts. Virginia opossums (Didelphis virginiana) and raccoons (Procyon lotor) are frequently identified as the principal reservoir hosts across the United States. This study sought to further dissect T. cruzi disease dynamics in south Texas. My objectives consisted of 1) estimating T. cruzi prevalence in three host species: Virginia opossum, raccoon, and striped skunk (Mephitis mephitis); and 2) determining if there is a sex-bias in T. cruzi parasitism among the three aforementioned host species. The study analyzed 94 blood and tissue samples from 30 meso-mammals captured and processed between 2012-13 using polymerase chain reaction (PCR) methodologies to screen for T. cruzi. The overall T. cruzi prevalence from 3 species of meso-mammals was 40% (12/30). Virginia opossums had the highest prevalence 71.4% (10/14) followed by raccoons 33.3% (1/3) and striped skunks 23.1% (3/13). No statistically significant difference in prevalence rates between males and females of the species tested was found. The overall prevalence in total number of females was 45.5% (5/11), and the overall prevalence in total number of males was 47.4% (9/19).

My results suggest that in south Texas, striped skunks should be considered a reservoir species of special concern in addition to raccoons and Virginia opossums. Additionally, my results indicate T. cruzi parasitism does not appear to differ between females and males of the mammalian reservoir species with the highest prevalence in south Texas; although, further research with a larger sample size could lead to more definitive results.