Detection of Trypanosoma cruzi DTUs TcI and TcIV in two outbreaks of orally-transmitted Chagas disease in the Northern region of Brazil

Abstract

This study describes the laboratory investigation of two acute Chagas disease outbreaks that occurred in the riverside communities of Marimarituba and Cachoeira do Arua, in the Santarem municipality, Para State, located in the Northern region of Brazil, and occurred in March 2016 and August 2017, respectively. The generation of data regarding the diversity of Trypanosoma cruzi parasites circulating in the Amazon region is key for understanding the emergence and expansion of Chagas disease. This study aimed to identify T. cruzi Discrete Typing Units (DTUs) involved in two outbreaks of acute Chagas disease (ACD) directly from the patient's biological sample. Nested and multiplex PCR targeting the 24Sα (rRNA) and mini-exon genes, respectively, were used to identify T. cruzi DTU in blood samples from patients diagnosed with ACD. The samples with positive cPCR were submitted for analysis for T. cruzi DTUs, which included 13 samples from the patients with ACD by oral transmission and two samples collected from two newborns of two women with ACD, from Marimarituba and Cachoeira do Arua. The samples were classified as T. cruzi TcIV, from Marimarituba's outbreak, and T. cruzi TcI, from Cachoeira do Arua's outbreak. The molecular identification of T. cruzi may increase understanding of the role of this parasite in Chagas disease's emergence within the Amazon region, contributing to the improvement of the management of this important, but also neglected, disease.

Figure 1. Distribution of analyzed cases according to outbreak, cPCR results and T. cruzi DTUs.

Figure 2. Genotyping patterns of T. cruzi sequences: SL-IR (A and B) and 24Sα rRNA (C and D). Reference strains (GeneBank accession code): TcI – JR cl4 (HQ604893.1), 110-bp; TcII – Y (AF301912), 125-bp; TcIII – MT3663 (AF303060) 110-bp; TcIV – JJ (AY491761), 120-bp; TcV – Bertha (FJ555614), 125 and 110-bp and TcVI – CLBrener (AF245383), 125-bp. Marimarituba’s samples (A and C): 3001, 3002, 3004, 3007, 3008, 3018, 3022, 3328. Cachoeira do Arua’s samples (B and D): 5030 to 5036. MM: 100-bp Molecular Weight Marker.