Abstract
Understanding the blood meal patterns of insects that are vectors of diseases is fundamental in unveiling transmission dynamics and developing strategies to impede or decrease human–vector contact. Chagas disease has a complex transmission cycle that implies interactions between vectors, parasites and vertebrate hosts. In Ecuador, limited data on human infection are available; however, the presence of active transmission in endemic areas has been demonstrated. The aim of this study was to determine the diversity of hosts that serve as sources of blood for triatomines in domestic, peridomestic and sylvatic transmission cycles, in two endemic areas of Ecuador (central coastal and southern highland regions). Using conserved primers and DNA extracted from 507 intestinal content samples from five species of triatomines (60 Panstrongylus chinai, 17 Panstrongylus howardi, 1 Panstrongylus rufotuberculatus, 427 Rhodnius ecuadoriensis and 2 Triatoma carrioni) collected from 2006 to 2013, we amplified fragments of the cytb mitochondrial gene. After sequencing, blood meal sources were identified in 416 individuals (146 from central coastal and 270 from southern highland regions), achieving ≥ 95% identity with GenBank sequences (NCBI-BLAST tool). The results showed that humans are the main source of food for triatomines, indicating that human–vector contact is more frequent than previously thought. Although other groups of mammals, such as rodents, are also an available source of blood, birds (particularly chickens) might have a predominant role in the maintenance of triatomines in these areas. However, the diversity of sources of blood found might indicate a preference driven by triatomine species. Moreover, the presence of more than one source of blood in triatomines collected in the same place indicated that dispersal of vectors occurs regardless the availability of food. Dispersal capacity of triatomines needs to be evaluated to propose an effective strategy that limits human–vector contact and, in consequence, to decrease the risk of T. cruzi transmission.
Highlights
The identification of species present in blood meals is an important strategy to understand the implication of hematophagous vector species in disease transmission and their ecological interactions
Analyses were carried out in 507 selected samples of DNA purified from the intestinal content of five species of triatomines (60 P. chinai, 17 P. howardi, 1 P. rufotuberculatus, 427 R. ecuadoriensis and 2 T. carrioni) previously collected from 2006 to 2013 in the central coastal (CC) (n = 171) and southern highland (SH) (n = 336) regions of Ecuador (Figure 1)
For 6.1% (n = 31) of the samples, the obtained sequences matched with a reported species in GenBank, but the identity was
Summary
The identification of species present in blood meals is an important strategy to understand the implication of hematophagous vector species in disease transmission and their ecological interactions. Important epidemiological traits of neglected tropical diseases (NTDs), such as the transmission of pathogens across multiple taxa, primary vector species, vertebrate species with a role in transmission and even social and economic conditions that foster transmission risk, have been assessed for important vectors such as Culex [1,2], Phlebotomus [3,4], Aedes [5] and triatomines [6,7]. Chagas disease (CD) is considered as one of the NTDs and it is caused by the infection of humans with Trypanosoma cruzi. The primitive transmission of T. cruzi was restricted to the sylvatic transmission cycle (between triatomines and mammals without human participation); the gradual process of human settlement near the zoonotic transmission zone opened new niches for triatomines [8]
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