Multilocus genetic analysis of Trypanosoma cruzi supports non-domestic intrusion into domestic transmission in an endemic region of Colombia

Abstract

Trypanosoma cruzi, the causative agent of Chagas disease, is primarily transmitted to humans by hematophagous bugs of the Triatominae subfamily. In the Colombian Caribbean region, particularly on Margarita Island, T. cruzi transmission is highly endemic and associated with vectors such as Triatoma maculata and Rhodnius pallescens. Additionally, T. cruzi-infected Didelphis marsupialis are commonly found in close proximity to human dwellings. Given the complex transmission dynamics involving various domestic and non-domestic hosts, this study aimed to analyze 145 T. cruzi clones from twelve strains isolated from T. maculata, R. pallescens, and D. marsupialis using spliced leader intergenic region (SL-IR) sequences and nine polymorphic microsatellite loci. The results indicate the presence of a single polymorphic T. cruzi population, suggesting sustained local transmission dynamics between triatomines adapted to A. butyracea forests and peridomestic areas inhabited by synanthropic mammal reservoir such as D. marsupialis. Notably, this population appears to lack substructure, highlighting the importance of adopting an alternative eco-health approach to complement traditional chemical vector control methods for more effective and sustainable interruption of transmission.

Keywords: Chagas disease; Didelphis; Microsatellites; Multilocus genotypes; Triatominae; Trypanosoma cruzi.

Graphical abstract

Fig. 1

(a) Maximum likelihood (ML) tree generated using the SL-intergenic region of T. cruzi clones from Margarita Island analyzed in this study, along with reference strains for TcI reported in America. Tips are colored as indicated in the inset. Nodes are represented by shapes and sizes denoting bootstrap support based on 1000 replicates, as indicated. (b) Median-Joining network constructed with SL-intergenic region haplotypes detected in Margarita Island (A-M) and reference T. cruzi strains belonging to TcI_Dom reported in Colombia. The size of each node is proportional to the frequency of the haplotype. The number of mutational steps ≥4 is shown.

Fig. 2

Multilocus-genotype (MLG) composition discriminated by T. cruzi isolate. Each colour indicates a different MLG. Only two MLGs (green stripes and dotted red) were shared between isolates from R. pallescens and D. marsupialis. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 3

Neighbor-joining tree constructed from pair-wise genetic distance values derived from MLGs analysis in clones from Margarita Island. Blue, green, and red colors represent clones derived from T. maculata, R. pallescens, and D. marsupialis, respectively. Asterisk (*) denotes a well-supported cluster harboring clones from infrapopulations isolated from distinct metapopulations. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)