Absence of domestic triatomine colonies in an area of the coastal region of Ecuador where Chagas disease is endemic

Abstract

Rhodnius ecuadoriensis is considered the second most important vector of Chagas disease in Ecuador. It is distributed across six of the 24 provinces and occupies intradomiciliary, peridomiciliary and sylvatic habitats. This study was conducted in six communities within the coastal province of Guayas. Triatomine searches were conducted in domestic and peridomestic habitats and bird nests using manual searches, live-bait traps and sensor boxes. Synantrhopic mammals were captured in the domestic and peridomestic habitats. Household searches (n = 429) and randomly placed sensor boxes (n = 360) produced no live triatomine adults or nymphs. In contrast, eight nymphs were found in two out of six searched Campylorhynchus fasciatus (Troglodytidae) nests. Finally, Trypanosoma cruzi DNA was amplified from the blood of 10% of the 115 examined mammals. Environmental changes in land use (intensive rice farming), mosquito control interventions and lack of intradomestic adaptation are suggested among the possible reasons for the lack of domestic triatomine colonies

Dynamics of Sylvatic Chagas Disease Vectors in Coastal Ecuador Is Driven by Changes in Land Cover

“…While, for logistical reasons, our sampling was limited to one year in one location, results found are in agreement with other studies performed by our team over the last 10 years in other regions of Ecuador at different periods of the year (e.g. [8], [11], [20], [34], [38]), reinforcing their general relevance. Based on this accumulated knowledge, we propose a schematic framework identifying the factors affecting the distribution of sylvatic T. cruzi vectors over one year (Figure 7).…”

“…Although the occurrence of these vectors in Ecuador is well known [8], [34], [38], no detailed data on their temporal dynamics were available. Our findings confirm that the demographic structure of sylvatic R. ecuadoriensis population was dominated by nymphal stages over the year [8] and that aggregations occurred both in sylvatic habitats and closer to homes [8], [39].…”

Phylogeographic Pattern and Extensive Mitochondrial DNA Divergence Disclose a Species Complex within the Chagas Disease Vector Triatoma dimidiata

“…This view was further supported by subsequent molecular analyses [15], [18] and by ecological and biogeographic observations, including the absence of records of wild populations in Ecuador (in contrast with abundant observations elsewhere) and the discontinuous distribution of the species, with Ecuadorian populations isolated from their Colombian relatives by the Central Colombian Massif and the humid Chocó eco-region [10]. The fact that T. dimidiata populations seem to have disappeared from some formerly infested rural areas of Ecuador [49], [50] and appear to persist only in a few urban foci (Abad-Franch F, pers. obs.)…”

The impact of landscape transformation on the reinfestation rates of Rhodnius prolixus in the Orinoco Region, Colombia

“…This increase in changes in land use correlate strongly with the increase seen in re-infestation indexes. In addition to environmental changes, there is evidence for control interventions and absence of intradomestic adaptation as possible reasons for the lack of domestic Triatomine colonies in Ecuador (Grijalva et al, 2010) We acknowledge that there are multiple factors that could contribute to the results that we found on this study. Other relevant factors, such as housing characteristics, deprivation levels, history of control actions could contribute to the results found.…”