Blood meal sources of wild and domestic Triatoma infestans (Hemiptera: Reduviidae) in Bolivia: connectivity between cycles of transmission of Trypanosoma cruzi

Abstract

BackgroundChagas disease is a major public health problem in Latin America. Its etiologic agent, Trypanosoma cruzi, is mainly transmitted through the contaminated faeces of blood-sucking insects called triatomines. Triatoma infestans is the main vector in various countries in South America and recently, several foci of wild populations of this species have been described in Bolivia and other countries. These wild populations are suspected of affecting the success of insecticide control campaigns being carried out in South America. To assess the risk that these T. infestans populations pose to human health, it is helpful to determine blood meal sources.MethodsIn the present work, blood meals were identified in various Bolivian wild T. infestans populations and in three specific areas, in both wild and intra-peridomestic populations to assess the links between wild and domestic cycles of T. cruzi transmission. PCR-HDA and sequencing of Cytb gene were used to identify these blood meal sources.Results and discussionFourteen vertebrate species were identified as wild blood meal sources. Of those, the most prevalent species were two Andean endemic rodents, Octodontomys gliroides (36 %) and Galea musteloides (30 %), while humans were the third most prevalent source (18.7 %). Of 163 blood meals from peridomestic areas, more than half were chickens, and the others were generally domestic animals or humans. Interestingly, blood from wild animals was identified in triatomines captured in the peridomestic and domestic environment, and blood from domestic animals was found in triatomines captured in the wild, revealing links between wild and domestic cycles of T. cruzi transmission.ConclusionThe current study suggests that wild T. infestans attack humans in the wild, but is also able to bite humans in domestic settings before going back to its natural environment. These results support the risk to human health posed by wild populations of T. infestans.

Trypanosoma cruzi load in synanthropic rodents from rural areas in Chile

“…Rodents are frequently found in triatomines’ blood meals [ 24 , 25 ]. If the rodent species sampled in our study are a food source for triatomines, their high infection levels with T. cruzi may be indicating that wild or peridomestic triatomines are getting these parasites through their blood meals, and in this way they are favoring the transmission of T. cruzi in the wild and peridomestic cycles.…”

Modelling geospatial distributions of the triatomine vectors of Trypanosoma cruzi in Latin America

“…distributions may also have changed [6]. It is now vital to understand the full community of vector species, including previously dominant vectors as well as secondary or minor vector species, in order to target residual transmission to humans [6][7][8].…”

“…Before the current intervention era, five vector species were recognised as being dominant in the transmission of T. cruzi to humans based on their habit of colonising houses, behaviour (feeding-defecation interval) and widespread geographical distributions [ 5 ]. Since indoor residual spraying (IRS) campaigns have successfully targeted these dominant species in many locations, their importance relative to other vectors has diminished and their geographical distributions may also have changed [ 6 ]. It is now vital to understand the full community of vector species, including previously dominant vectors as well as secondary or minor vector species, in order to target residual transmission to humans [ 6 – 8 ].…”

Within-host temporal fluctuations of Trypanosoma cruzi discrete typing units: the case of the wild reservoir rodent Octodon degus

“…Several species of sylvatic mammals have been found naturally infected with T. cruzi in different geographical areas [ 12 – 16 ]. Some of these serve as reservoir hosts of T. cruzi as described by Begon [ 17 ].…”