Molecular techniques integrated to the entomological surveillance of Chagas disease vectors

Study of the secondary vector Triatoma sordida in the Eastern Region of Paraguay

Abstract

When molecular techniques for the detection of natural infection and blood meal source in secondary vectors of Chagas disease are applied to specimens captured in endemic areas, historically occupied by Triatoma infestans, provide more accurate answers to questions about transmissibility of the illness and further contribute to the epidemiological studies. The aim of this study was to evaluate the impact of intra and peridomiciliary infestation of Triatoma sordida in households from the departments of the Eastern Region of Paraguay, under entomological surveillance during the period 2007 to 2015, by using the molecular biomarkers technology. A total of 559 specimens of T. sordida captured in 253, 91 and 52 households from Paraguarí, San Pedro and Cordillera departments, respectively, were analyzed. The infestation detected was from 24% to 48% as well as a high intradomicialiary colonization from 5% to 36% in the three departments. The molecular detection of natural infections ranged from 14% to 44% and in 111 specimens the meal source was identified. The molecular marker cytochrome b allowed to demonstrate, for the first time, high frequency of triatomines with human blood as a food source, mainly in Cordillera as it was determined in 82% (28/34) of the T. sordida captured. These findings demonstrate a progress of T. sordida into the ecological niche of T. cruzi and the abillity of this secondary species as a vector of the transmission of T. cruzi in communities from the Eastern Region of Paraguay