Distribuição espacial e caracterização molecular das linhagens de Trypanosoma cruzi em triatomíneos em municípios do Agreste de Pernambuco

Abstract

Trypanosoma cruzi presents a heterogeneous population with seven lineages recognized, called Discrete Typing Units (DTU's). The knowledge of DTUs can contribute to a better understanding of the epidemiology of Chagas disease and the possible risk factors for infection to man. The study aimed to carry out an entomological survey of triatomines and molecularly characterize the lineages of T. cruzi present in vectors, in municipalities in the rural region of Pernambuco, Brazil. Based on data from the Programa Nacional de Controle da Doença de Chagas (PNCDCh), a retrospective study (2008-2017) was conducted to assess the occurrence and distribution of triatomines in 21 municipalities. In addition, during the period from July 2018 to June 2019, triatomines were collected in intradomicile and peridomicile area and identified for subsequent DNA extraction. The search for T. cruzi was carried out through parasitological and molecular exams. For the DNA research of Trypanosoma spp. PCR was performed, and the amplified products were purified and sequenced. T. cruzi genotyping was performed by Multiplex PCR. To evaluate the spatiotemporal distribution of triatomines infected by trypanosomatid parasites, data from the PNCDch (2008-2018) were used, the total number of triatomines captured from intradomicile and peridomicile areas, as well as the infection rate (IR) by trypanosomatid. The 𝐺𝑖∗method by Getis–Ord method was used to statistically identify significant concentration clusters and the IR of triatomines by trypanosomatids. A generalized linear regression model with binomial distribution was used to evaluate the probability of finding an IR by trypanosomatids. A total of 4694 triatomines were collected, 94.5% and 5.5% from the intradomiciliary and peridomiciliary environments. The most frequent species were Panstrongylus lutzi (30.36%), Triatoma brasiliensis (26.12%), Triatoma pseudomaculata (22.43%) and Panstrongylus megistus (20.54%). A total of 117 triatomines were collected, 93.16% and 6.84% from the intradomiciliary and peridomiciliary environments, respectively. The captured species were P. lutzi (37.60%), T. pseudomaculata (26.50%), T. brasiliensis (23.08%), and P. megistus (12.82%). In parasitological and molecular tests, the T. cruzi infection rate was 5.49% and 12.09%. The molecular analysis detected 70.59% of the TcI genotype in all triatomine species identified and 29.41% of the TcIII/TcIV in P. megistus and P. lutzi. The analysis of the spatiotemporal distribution of triatomines infected by trypanosomatids was performed with 4,800 triatomines. The flagellar forms similar to T. cruzi were detected in 10.29% of them, the majority of positive specimens (98.17%) were collected at intradomicile. The geospatial analyses identified triatomines clusters in intradomicile and peridomicile environments. The logistic regression for species (P. lutzi, P. megistus, T. Brasiliensis, and T. pseudomaculata) showed that the probability of detection of T. cruzi infection remains constant in up to 50 specimens examined or more. The presence of infected triatomines in intra and peridomicile areas calls for implementing surveillance actions, such as health education in areas where these vectors are most vulnerable. In addition, the adoption of systematic entomological control measures reduces the risks of infestation and, consequently, of Chagas disease