Serological and molecular inquiry of Chagas disease in an Afro-descendant settlement in Mato Grosso do Sul State, Brazil

Abstract

Furnas do Dionísio is a Brazilian Afro-descendant settlement in the city of Jaraguari, 21.4 miles from Campo Grande, Mato Grosso do Sul, Brazil. Approximately 96 families live in this quilombola (Maroon) settlement, also known in Brazil as a remnant community of descendants of African slaves. Recent studies found 20% of households were infested by triatomines, 18% of insects captured in the community were infected by Trypanosoma cruzi, and 22.7% of dogs presented T. cruzi antibodies. The low prevalence of Chagas disease observed in humans in Mato Grosso do Sul State is attributed to its arrival via colonist migration and subsequent transplacental transmission. In order to gain a better understanding of the T. cruzi cycle in residents of the study community, serological and molecular tests were carried out to diagnose Chagas disease. In the present study, 175 residents between 2 and 80 years old were included. A total of 175 participants were interviewed and 170 provided blood samples, which were tested for T. cruzi antibodies with serological tests. Molecular diagnosis was performed in 167 participants by PCR (KDNA) and NPCR (satellite DNA) tests. One of the 170 samples tested positive for all serological tests performed. The overall frequency of Chagas disease in the community was low (0.6%). Interview responses revealed that 66.3% knew of triatomine insects and 65.7% reported having had no contact with them. Physical improvements to residences, together with vector surveillance and control by the State and municipal governments and local ecological conservation contribute to the low frequency of the Chagas disease in this quilombola community.

Fig 1. PCR results, KDNA target.

M: Ladder 100 bp, Invitrogen ®; C+: T. cruzi DTU II; C-: DNA of patients who tested negative for Chagas disease; 75: PCR positive for T. cruzi KDNA; 74, 76–78: PCR negative for T. cruzi KDNA; W: PCR without DNA.

Fig 2. Nested PCR results, satellite DNA targets.

M: Ladder 100 bp, Invitrogen ®; C+: T. cruzi DTU II; C-: DNA of patients with negative serologies and epidemiologies for Chagas disease; 75: NPCR positive for T. cruzi satellite DNA; 76–78: PCR negative for T. cruzi satellite DNA; W: NPCR without DNA.