New scenarios of Trypanosoma cruzi transmission in the Orinoco region of Colombia

Abstract

Rhodnius prolixus, a blood-sucking triatomine with domiciliary anthropophilic habits, is the main vector of Chagas disease. The current paradigm of Trypanosoma cruzi transmission in Columbia includes a sylvatic and domiciliary cycle co-existing with domestic and sylvatic populations of reservoirs. The aim of this study is to evaluate the population densities and relative abundance of triatomines and mammals that may be involved in the sylvatic cycle of Chagas disease to clarify the epidemiological scenario in an endemic area in the province of Casanare. Insect vectors on Attalea butyracea palms were captured using both manual searches and bait traps. The capture of mammals was performed using Sherman and Tomahawk traps. We report an infestation index of 88.5% in 148 palms and an index of T. cruzi natural infection of 60.2% in 269 dissected insects and 11.9% in 160 captured mammals. High population densities of triatomines were observed in the sylvatic environment and there was a high relative abundance of reservoirs in the area, suggesting a stable enzootic cycle. We found no evidence of insect domiciliation. Taken together, these observations suggest that eco-epidemiological factors shape the transmission dynamics of T. cruzi, creating diverse scenarios of disease transmission.

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

“…Previous studies from our laboratory reported an infestation index (I.I.) of 88.5% from 148 palms and index of natural infection with T. cruzi of 60.2% in 269 dissected insects and 11.9% infection in 160 mammals belonging to four orders and six families (Rendón et al, 2015). Pinto et al 2005, reported 100% I.I.…”

Is vectorial transmission of Trypanosoma cruzi an efficient route to support high infection rates in sylvatic hosts?

“…For example, bats can play an important role in transmission scenarios, because their high mobility allows the parasite to migrate between the sylvatic and domestic habitat. Studies carried out in Casanare in different bat species reported infection indexes of T. cruzi from 6.5% to 51% [26, 30]. Moreover, Didelphis marsupialis has been considered one of the main reservoirs of the parasite and previous studies suggest infection rates ranging from 5 to 90% [31-32].…”

Modeling the effects of palm-house proximity on the theoretical risk of Chagas disease transmission in a rural locality of the Orinoco basin, Colombia

“…While some triatomines are opportunistic palm inhabitants, one study suggested that most of the species in the tribe Rhodniini are palm-specialized [9]. In Colombia, natural infections with T. cruzi have been found in 15 triatomine species [10], with Rhodnius prolixus as the main vector since it has domiciliary anthropophilic habits and has a wide geographical distribution in the Orinoco region [7, 11, 12]. …”

“…Previous work from our group in the municipality of Mani Casanare (Orinoco region) [12], found that Attalea butyracea , a large-crowned palm, is ubiquitous and has large R. prolixus densities [7, 13] with high natural rates of infection with T. cruzi [12]. Interestingly, the same study reported low colonization indices of households [12] and residents mentioned often seeing adult insects come by at night supposedly attracted by lights [14].…”

“…Interestingly, the same study reported low colonization indices of households [12] and residents mentioned often seeing adult insects come by at night supposedly attracted by lights [14]. Taken together, the close vector-palm association and the proximity between houses and palms, despite low domiciliation, create a unique mixture of risk factors that may partially explain the endemicity of the region [7].…”