Trypanosoma cruzi infection in dogs (Canis lupus familiaris) and study of the triatomine fauna in the Agreste region of Pernambuco, Brazil
Vectors; Chagas disease; American trypanosomiasis; Spatial distribution; Canine infection.
Trypanosoma cruzi (Kinetoplastea: Trypanosomatidae) is the etiological agent of Chagas disease (CD), also known as American trypanosomiasis (AT). This parasite exhibits a heterogeneous population structure with seven recognized lineages, referred to as Discrete Typing Units (DTUs). Dogs are important domestic hosts of T. cruzi, serving as models for understanding the clinical manifestations of the disease and providing information on the current distribution of this infection in Brazil. The overall objective of this study was to investigate T. cruzi infection in dogs and to study the triatomine fauna in the Agreste region of Pernambuco, Brazil. To this end, this dissertation is organized into three chapters, as described below. Chapter 1: The distribution and infection rates of T. cruzi in triatomines collected in a Chagas disease endemic region of northeastern Brazil were evaluated. Secondary data obtained between 2013 and 2022 from the Official System of the National Chagas Disease Control Program (SisPCDCh) were used. A total of 7,257 triatomine specimens were collected, most of which (6,792; 93.6%) were found indoors, while 465 (6.4%) were collected in peridomestic areas. The most frequent species were Panstrongylus lutzi (39.8%), followed by Triatoma brasiliensis (37%), T. pseudomaculata (18.5%), and P. megistus (4.32%). Among these triatomines, 7.1% were found to harbor trypomastigote forms compatible with T. cruzi. Chapter 2: Available data on T. cruzi infection in dogs in Brazil were synthesized, with emphasis on case distribution and diagnostic methods applicable to veterinary clinical practice. This analysis highlighted the scarcity of information on the nationwide distribution of canine infection, with a predominance of case reports and post-mortem studies. Chapter 3: The occurrence of T. cruzi infection was determined in dogs from municipalities endemic for Chagas disease in the Agreste region of Pernambuco. Overall, 21 animals tested positive: 11.11% (17/153) by indirect immunofluorescence assay (IFA) and 1.59% (4/251) by PCR. The presence of triatomines and dogs infected with the etiological agent underscores the need to intensify surveillance actions, particularly health education initiatives, in areas of greater vulnerability where human populations live in close contact with vectors and/or dogs. The adoption of systematic entomological control measures, combined with improvements in human housing conditions, may help reduce the risk of infestation and, consequently, the transmission of Chagas disease.