Retrospective distribution of Trypanosoma cruzi I genotypes in Colombia

Abstract

Trypanosoma cruzi is the aetiological agent of Chagas disease, which affects approximately eight million people in the Americas. This parasite exhibits genetic variability, with at least six discrete typing units broadly distributed in the American continent. T. cruzi I (TcI) shows remarkable genetic diversity; a genotype linked to human infections and a domestic cycle of transmission have recently been identified, hence, this strain was named TcIDom. The aim of this work was to describe the spatiotemporal distribution of TcI subpopulations across humans, insect vectors and mammalian reservoirs in Colombia by means of molecular typing targeting the spliced leader intergenic region of mini-exon gene. We analysed 101 TcI isolates and observed a distribution of sylvatic TcI in 70% and TcIDom in 30%. In humans, the ratio was sylvatic TcI in 60% and TcIDom in 40%. In mammal reservoirs, the distribution corresponded to sylvatic TcI in 96% and TcIDom in 4%. Among insect vectors, sylvatic TcI was observed in 48% and TcIDom in 52%. In conclusion, the circulation of TcIDom is emerging in Colombia and this genotype is still adapting to the domestic cycle of transmission. The epidemiological and clinical implications of these findings are discussed herein.

Molecular Diagnosis of Chagas Disease in Colombia: Parasitic Loads and Discrete Typing Units in Patients from Acute and Chronic Phases

“…cruzi parasite shows significant genetic variability and classified into at least six Discrete Typing Units TcI-TcVI (DTUs), that present associations with the geographical distribution, epidemiological transmission cycles, insect vectors and clinical manifestations of Chagas disease [ 3 – 5 ]. Recent studies suggest the occurrence of an emerging clade within TcI named TcIDom which is distributed in the Americas and associated with domestic cycles of transmission and human infection [ 6 – 10 ]. Recently, a genotype detected in anthropogenic bats and named as TcBat has been described in Panama, Ecuador, Colombia and Brazil including a case of human infection in Colombia [ 11 – 14 ].…”

Trypanosoma cruzi I genotype among isolates from patients with chronic Chagas disease followed at the Evandro Chagas National Institute of Infectious Diseases (FIOCRUZ, Brazil)

“…, and thereafter mentioned by several authors 7,8,55,56 . Analysis of the spliced-leader intergenic region (SL-IR) of several TcI stocks evidenced five SL-IR groups (TcIa-TcIe) correlated with transmission cycles [57][58][59][60] .…”

“…Llewellyn et al 54 disclosed an exclusively domestic genotype (Ven DOM ), subsequently named TcI DOM , which corresponds to the TcIa SL-IR group 61 . More recently, León et al 56 suggested the subdivision of TcI only into two main groups (TcI DOM and sylvatic), proposing a PCR assay for identifying them. In the present study, the sequencing analysis of the TcI isolate (CT-IOC 541) showed that it is genetically closer to Sylvio X10, a stock identified as TcId 60 , a sub-group related to sylvatic cycles, which was also found by Câmara et al 38 in Northeastern Brazil.…”

Multilocus sequence typing: genetic diversity in Trypanosoma cruzi I (TcI) isolates from Brazilian didelphids

“…Our data showed that isolates appeared in different clusters in the individual trees (Additional file 1 : Figure S1 and Additional file 2 : Figure S2). The existence of incongruences between constitutive gene trees has previously been observed in different lineages [ 19 , 40 , 45 , 57 ] and it is considered a marker of populations that have undergone genetic recombination. The evidence for recombination is further supported by haplotypic phylogenies that infer allelic inheritance from homozygous donor genotypes.…”

“…TcI is widespread from the southern USA to northern Argentina and Chile and infects many different mammal host including humans, domestic and sylvatic species, transmitted by triatomine bug vectors. TcI is the most frequently sampled DTU in wild transmission cycles, although it was also observed in domestic cycles [ 19 , 20 ] and is the dominant DTU in terms of Chagas disease transmission in endemic regions north of the Amazon Basin [ 21 ]. In Brazil, TcI represents 58% of recovered sylvatic T. cruzi isolates [ 8 ].…”