Search

Chagas disease is caused by Trypanosoma cruzi and transmitted by the triatomine Mepraia spinolai in the southwest of South America. Here, we examined the T. cruzi-infection dynamics of field-caught M. spinolai after laboratory feeding, with a follow-up procedure on bug populations collected in winter and spring of 2017 and 2018. Bugs were analyzed twice to evaluate T. cruzi-infection by PCR assays of urine/fecal samples, the first evaluation right after collection and the second 40 days after the first feeding. We detected bugs with: the first sample positive and second negative (+/-), the first sample negative and second positive (-/+), and with both samples positive or negative (+/+; -/-). Bugs that resulted positive on both occasions were the most frequent, with the exception of those collected in winter 2018. Infection rate in spring was higher than winter only in 2018. Early and late stage nymphs presented similar T. cruzi-infection rates except for winter 2017; therefore, all nymphs may contribute to T. cruzi-transmission to humans. Assessment of infection using two samples represents a realistic way to determine the infection a triatomine can harbor. The underlying mechanism may be that some bugs do not excrete parasites unless they are fed and maintained for some time under environmentally controlled conditions before releasing T. cruzi, which persists in the vector hindgut. We suggest that T. cruzi-infection dynamics regarding the three types of positive-PCR results detected by follow-up represent: residual T. cruzi in the rectal lumen (+/-), colonization of parasites attached to the rectal wall (-/+), and presence of both kinds of flagellates in the hindgut of triatomines (+/+). We suggest residual T. cruzi-infections are released after feeding, and result 60-90 days after infection persisting in the rectal lumen after a fasting event, a phenomenon that might vary between contrasting seasons and years., Competing Interests: The authors have declared that no competing interests exist.

A widely accepted idea in parasite-host relationships is that the former manipulates the latter so that it increases its own success. In the case of complex life cycles, this means that the parasite is able to manipulate the first host which allows its transmission to the second host. In this paper, I formalize the idea that this may be the case for the Trypanosoma cruzi parasite and its vectors, bugs of the subfamily Triatominae. I discuss the sources of existing evidence and propose some types of manipulation. This manipulation could also occur in the second host, that is, a vertebrate. Here, I emphasize humans and domesticated animals. I also discuss how global change and insecticide resistance may drive the arms race between both, triatomines and T. cruzi, and host manipulation., Competing Interests: Declaration of Competing Interest While submitting the manuscript Chagas bugs and Trypanosoma cruzi: puppets and puppeteer? I want to state that I have no conflict of interest as I am the sole author of this work., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Kissing bugs (Hemiptera: Reduviidae: Triatominae) are able to bend their rod-like maxillae while searching for blood vessels in the tissue of their vertebrate hosts. Little is known about the working mechanisms of these bending movements and the distal opening of the food channel. We compared the morphological structure of the stylets (mandibles and maxillae) of four triatomine species and analyzed the feeding process of Dipetalogaster maxima (Uhler, 1894). The maxillae of triatomine bugs are interlocked by a tongue-and-groove system, allowing longitudinal sliding. While penetrating the host tissue, the animals perform rapid alternate back and forth movements of the maxillae. The resistance of the surrounding tissue pushes the asymmetric apex of the maxillae away from its straight path, i.e., if one individual maxilla is protracted alone, its tip curves inwards, and the other maxilla follows. Once a blood vessel is tapped, the spine-like tip of the left maxilla splays outwards. Apically, each of the maxillae features an abutment, the left one exhibiting a notch that presumably facilitates splaying. The mechanical interaction of the two maxillary abutments enables the distal opening of the food channel but might also support the movements of the maxillary bundle attributable to different bending moment distributions., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The transmission of Trypanosoma cruzi to humans is determined by multiple ecological, socio-economic and cultural factors acting at different scales. Their effects on human infection with T. cruzi have often been examined separately or using a limited set of ecological and socio-demographic variables. Herein, we integrated the ecological and social dimensions of human infection risk with the spatial distribution patterns of human and vector (Triatoma infestans) infection in rural communities of the Argentine Chaco composed of indigenous people (90% Qom) and a creole minority. We conducted serosurveys in 470 households aiming at complete population enumeration over 2012-2015. The estimated seroprevalence of T. cruzi prior to the implementation of an insecticide spraying campaign (2008) was 29.0% (N = 1,373 in 301 households), and was twice as large in Qom than creoles. Using generalized linear mixed models, human seropositive cases significantly increased with infected triatomine abundance, having a seropositive household co-inhabitant and household social vulnerability (a multidimensional index of poverty), and significantly decreased with increasing host availability in sleeping quarters (an index summarizing the number of domestic hosts for T. infestans). Vulnerable household residents were exposed to a higher risk of infection even at low infected-vector abundances. The risk of being seropositive increased significantly with house infestation among children from stable households, whereas both variables were not significantly associated among children from households exhibiting high mobility within the communities, possibly owing to less consistent exposures. Human infection was clustered by household and at a larger spatial scale, with hotspots of human and vector infection matching areas of higher social vulnerability. These results were integrated in a risk map that shows high-priority areas for targeted interventions oriented to suppress house (re)infestations, detect and treat infected children, and thus reduce the burden of future disease., Competing Interests: The authors have declared that no competing interests exist.

The genus Belminus Stål, 1859 is distinguished by markedly entomophagous species. This genus is a poorly studied group of the Triatominae (Jeannel, 1919), which includes hematophagous species that are vectors of Trypanosoma cruzi (Chagas, 1909), the etiological agent of Chagas disease. This study reports for the first time the description of the antennal sensilla of Belminus corredori (Galvão & Angulo, 2003), Belminus herreri (Lent & Wygodzinsky, 1979), and Belminus ferroae (Sandoval, Pabón, Jurberg & Galvão, 2007) nymphs and adults throughout scanning electron microscopy and optical microscopy. Nine morphological types of sensilla were identified in the three species, including bristles I and II, trichobothria, tapered hairs, thin-walled trichoid, thick-walled trichoid, basiconic, campaniform, and coeloconica sensilla. The analysis of the most abundant types of sensilla and their distribution in nymphs and adults shows similarities with the antennal phenotypes described in other Triatominae. Quantitative differences showed the important phenotypic plasticity of this morphological trait in the genus and allowed for the separation of the species in both sexes. These differences were associated with sexual dimorphism and wing condition (macropterous and brachypterous). The role of the antennal phenotype in sexual behavior, its usefulness as a taxonomic tool, and its relationship with the dispersal capacity of these species are discussed., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The etiologic agent of Chagas disease, Trypanosoma cruzi, is transmitted by hematophagous insect vectors that subsist on repeated blood meals over their lives separated by periods of fasting. Using naturally infected Mepraia spinolai, we measured the influence of parasite infection on this host vector's mortality during regular feeding and after fasting. After their capture, the insects were fed twice with uninfected mice to evaluate parasitic infection in their fecal samples by microscopic observation and PCR. Then the insects were subjected to a fasting period, followed by a third (final) feeding. After each feeding, a fecal sample was obtained to evaluate T. cruzi infection. To determine its progress through ontogeny, mortality and ecdysis of the infected and uninfected nymphs and adults were recorded on three occasions, over 140 d, and analyzed. Detections of infection by T. cruzi between the two first feedings increased, but this detection level was generally reduced after final feeding unless reinfected. For nymphs (stages III-V), their mortality was highest when infected after the fasting period, whereas adults were equally resistant to death after fasting when infected with T. cruzi. Metacyclic trypomastigotes were principally excreted in the fecal samples. Our results confirm that T. cruzi is pathogenic to its invertebrate hosts under nutritional stress conditions, when nymphs' mortality is higher while infected than uninfected when they were hungry. These results are epidemiologically important because T. cruzi harms the fasting vector M. spinolai, reducing its lifespan and competence as a disease vector, and thereby its rates of parasite transmission., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Chagas disease (CD) is a life-threatening illness caused by the protozoan parasite Trypanosoma cruzi, which is transmitted by triatomine bugs. Triatomine bugs inhabit poorly constructed homes that create multiple hiding spots for the bugs. Modifying the actual structure of a home, along with the homeowners' practices, can reduce triatomine infestation. This research was designed to collect culturally-relevant information to develop a health campaign to decrease risk of CD transmission by promoting home maintenance and better hygiene in rural communities of southern Ecuador., Methods and Main Findings: The Health Belief Model (HBM) guided focus group discussions and the interpretation of the results. Four focus groups ranging from 4 to 10 participants were conducted between May and June 2014 in three communities of Loja province in Southern Ecuador. A thematic analysis was used to identify within the data related to perceptions of susceptibility, severity, benefits, barriers and self-efficacy related to CD and its prevention. The results provide clear guidance for the development of Chagas-prevention messages., Conclusion: Data obtained emphasize the importance of standardizing messages presented to the communities for CD prevention. Messages should provide more information on the protective nature of the behaviors promoted for CD prevention; overcoming barriers such as cost and convenience, and build on facilitating factors, including community members' interest on quality of life, protection of their families, and relationship with the land., Competing Interests: The authors have declared that no competing interests exist.

Introduction: This article reports, for the first time, the occurrence of Panstrongylus megistus in the Brazilian Western Amazon., Methods: Specimens of P. megistus were collected in the cities of Rio Branco, Acre and Extrema, Rondônia., Results: The number of triatomine species in the State of Acre increased from eight to nine and in Rondônia from seven to eight. This was also the first report of P. megistus in the Brazilian Western Amazon., Conclusion: The occurrence of P. megistus in the Western Amazon evidences an epidemiological alert, since it is an important vector of T. cruzi., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Laboratory-reared hematophagous triatomines that are the main vectors of Chagas disease are generally fed on small vertebrates or on blood-filled membrane devices. Such devices allow a large-scale rearing of these vectors without sacrificing host animals but are almost always expensive, fragile, not easily purchased, and usually difficult to use because they need to be sterilized before and carefully cleaned after each feeding. We present here a simple device to feed triatomines that is composed of a circular series of alternating short pieces of stainless steel and silicon tubing connected to a pump that circulates water heated at 50° C in a water bath. An unlubricated condom filled with 50ml of blood, is fixed around each steel tube section and placed onto the screened tops of containers with triatomines. Nymphs and adults access the blood source by climbing a vertical piece of folded filter paper. After feeding, each condom can be easily and safely removed and discarded. This device consists of simple, cheap, safe and robust components that can be easily purchased, assembled and used. Contamination during or after feeding is practically excluded. The technique is successfully used in our Laboratory for almost two years., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Mepraia spinolai (Porter) is a vector of Trypanosoma cruzi that causes Chagas disease. Females are always wingless, but males may be winged or wingless. We determined by PCR the infection percentage with T. cruzi of M. spinolai adults and nymphs in domestic, peridomestic, and wild collections, in different regions of Chile. In all regions, winged males were more abundant than females and wingless males. Winged males collected inside houses were less parasitized than were those from peridomestic and wild environments. Although winged males of M. spinolai have comparatively low levels of infection, this segment may still represent the greatest vector threat in this species for transmission of T. cruzi to humans and other vertebrates in domestic, wild, and peridomestic habitats. Winged males represent the dispersive form of this species that invades human dwellings. Feeding deprivation resulting from the time required to find a food source and to search for reproductive females could explain the lower infection rates (negatives) of winged males collected from inside houses in comparison with winged males collected from peridomestic and wild habitats., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Introduction: Trypanosoma cruzi has been divided by international consensus into six discrete typing units (DTU): TcI, TcII, TcIII, TcIV, TcV y TcVI. The factors determining the dynamics of T. cruzi genotypes vector transmission of Chagas' disease in the different geographical regions of Perú are still unknown., Objective: To detect and type T. cruzi DTUs from the faeces of seven species of triatomines (Panstrongylus chinai, P. geniculatus, P. herreri, Rhodnius robustus, R. pictipes, Triatoma carrioni and T. infestans) captured in eight departments from different natural regions of Perú., Materials and Methods: We examined 197 insects for detecting trypanosomes. DNA was extracted from each insect intestinal contents and PCR amplification of kDNA, SL-IR, 24Sα rRNA and 18Sα RNA was performed for detecting T. cruzi DTUs., Results: Five T. rangeli and 113 T. cruzi infections were detected; 95 of the latter were identified as TcI (two in P. chinai, one in P. geniculatus, 68 in P. herreri, four in R. pictipes, seven in R. robustus, one in T. carrioni, 12 in T. infestans), five as TcII (four in P. herreri, one in T. infestans), four as TcIII (three in P. herreri, one in R. robustus) and four TcIV infections in P. herreri., Conclusions: This is the first study which has attempted a large-scale characterization of T. cruzi found in the intestine of epidemiologically important vectors in Perú, thus providing basic information that will facilitate a better understanding of the dynamics of T. cruzi vector transmission in Perú.

Understanding the biological parameters of some triatomine subspecies of Meccus phyllosomus (Burmeister) is a crucial first step in estimating the epidemiologic importance of this group. Biological parameters related to hatching, lifetime, number of blood meals to molt, percentage of females at the end of the cycle, number of laid eggs, and mortality for each instar of 3 M. phyllosomus subspecies [M. p. mazzottii (Usinger), M. p. pallidipennis (Stål), and M. p. phyllosomus] and their laboratory hybrids were evaluated and compared. No significant differences (P > 0.05) were found among the experimental hybrids (MaPa, MaPhy, PaPhy) and reciprocal cohorts. In 5 (hatching, number of blood meals to molt, accumulative mortality, percentage of females, and mean number of laid eggs) of the 6 studied parameters (with the exception of development time), the hybrid cohorts had better fitness results than the parental cohorts involved in each set of crosses. The increase in hybrid fitness found in our study could lead to an increase in the epidemiologic risks caused by transmission of Trypanosoma cruzi to humans., (© 2015 Institute of Zoology, Chinese Academy of Sciences.)

American trypanosomiasis is a chronic disease transmitted mainly by vectors. The hematophagous triatomine vectors transmit Trypanosoma cruzi to a wide variety of mammals, which usually are their food source. This study determined the feeding profile of Mepraia spinolai, a sylvatic triatomine vector, present in endemic areas of Chile. Vectors were captured in the north-central area of Chile. Samples of intestinal contents were analyzed by an Enzyme-linked immunosorbent assay (ELISA) that identifies and discriminates the presence of serum antigens from Homo sapiens and nine animal species (Canis familiaris, Felis catus, Capra hircus, Mus musculus, Gallus gallus, Octodon degus, Thylamys elegans, Phyllotis darwini and Oryctolagus cuniculus). Our data indicate the most frequent feeding source in this area was P. darwini, followed by O. degus, O. cuniculus, M. musculus, G. gallus, T. elegans, C. familiaris, F. catus and C. hircus. Mixed food sources were also identified., (Copyright © 2016 Elsevier B.V. All rights reserved.)

For a long time, haematophagy was considered an obligate condition for triatomines (Hemiptera: Reduviidae) to complete their life cycle. Today, the ability to use haemolymphagy is suggested to represent an important survival strategy for some species, especially those in genus Belminus. As Eratyrus mucronatus and Triatoma boliviana are found with cockroaches in the Blaberinae subfamily in Bolivia, their developmental cycle from egg to adult under a "cockroach diet" was studied. The results suggested that having only cockroach haemolymph as a food source compromised development cycle completion in both species. Compared to a "mouse diet", the cockroach diet increased: (i) the mortality at each nymphal instar; (ii) the number of feedings needed to molt; (iii) the volume of the maximum food intake; and (iv) the time needed to molt. In conclusion, haemolymph could effectively support survival in the field in both species. Nevertheless, under laboratory conditions, the use of haemolymphagy as a survival strategy in the first developmental stages of these species was not supported, as their mortality was very high. Finally, when Triatoma infestans, Rhodnius stali and Panstrongylus rufotuberculatus species were reared on a cockroach diet under similar conditions, all died rather than feeding on cockroaches. These results are discussed in the context of the ecology of each species.

Triatomines, vectors of Chagas Disease, are hematophagous insects. Efforts have been made to develop synthetic attractants based on vertebrate odor-to lure them into traps. However, because those lures are not practical or have low capture efficiency, they are not in use in control programs. Therefore, more work is needed to reach a practical and efficient odor lure. Recently, a three-component, CO 2 -free, synthetic blend of vertebrate odor (consisting of ammonia, l-(+)-lactic acid, and hexanoic acid), known as Sweetscent (Biogents AG, Regensburg, Germany), was shown to attract and capture triatomines in the laboratory. In this study, using a trap olfactometer and an odor blend with constituents similar to those of Sweetscent (delivered from low-density polyethylene sachets) we found that the odorant ratios of the mixtures have a strong effect in the capture of triatomines. The blend with the most efficient combination of odorant ratios evoked ca. 81% capture in two relevant triatomine species. In the case of the most effective odor mixtures, we measured the odor mass emission for the three components of the mixture and therefore were able to estimate the odorant ratios emitted that were responsible for such a high capture performance. Thus, in those mixtures, pentanoic acid was the main component (ca. 65 %) followed by ammonia (ca. 28%) and, l(+)-lactic acid (ca. 7 %). Our results are encouraging as efficient, practical, and cheap odor baits to trap triatomines in the field would be within reach. The odor-delivery system used should be improved to increase stability of odor emission., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Cavernicola pilosa is a triatomine species that lives in caves and feeds on bat blood. This vector has a wide geographical distribution, and is found in Brazil, Colombia, Panama, Peru, and Venezuela. Little is known about the reproductive biology of this species, because most previous studies have only characterized its morphology, morphometry, ecology, and epidemiology. Therefore, this study aimed to obtain preliminary data related to spermatogenesis in C. pilosa by conducting cytogenetic analysis. Analysis of the heterochromatic pattern of C. pilosa during the initial prophases revealed that heterochromatic blocks are only present in the sex chromosomes. Based on the analyses of the meiotic metaphase and prophases, we found that the sex determination system of C. pilosa is XY and the chromosomes are holocentric. C. pilosa spermatids are filamentous and have long flagella. It was not possible to detect corpuscle or filament heteropycnosis in spermatids of this species. The initial cytogenetic data presented in this study are important in characterizing the spermatogenesis and heterochromatic patterns of C. pilosa. Our results suggest that adaptation to troglodytism did not result in differences in spermatogenesis in this vector.

We analyzed the classical cytotaxonomy of the Brasiliensis subcomplex (Triatoma brasiliensis Neiva, T. juazeirensis Costa & Felix, T. melanica Costa, Argolo & Felix, T. melanocephala Neiva & Pinto, T. petrochiae Pinto & Barreto, T. lenti Sherlock & Serafim, T. sherlocki Papa, Jurberg, Carcavallo, Cerqueira & Barata, T. tibiamaculata Pinto and T. vitticeps Stal) and the T. brasiliensis complex (T. b. brasiliensis, T. b. macromelasoma Neiva & Lent, T. juazeirensis, T. melanica and T. sherlocki). The five members of the T. brasiliensis complex share the same cytogenetic characteristics. Merely T. sherlocki show differences in spermatids, which confirms the status of more differentiated member of the complex. T. lenti also presented the same cytogenetic characteristics described for the species of the T. brasiliensis complex, which supports possible grouping of the species as sixth member of the complex, although further analysis as molecular and experimental crosses are needed to corroborate this hypothesis. T. petrochiae, T. vitticeps, T. tibiamaculata and T. melanocephala presented one or more characteristics that allow questioning grouping in the proposed Brasiliensis subcomplex. Thus, we suggested that Brasiliensis subcomplex and T. brasiliensis complex should be constituted by the same triatomines (T. b. brasiliensis, T. b. macromelasoma, T. juazeirensis, T. melanica and T. sherlocki). However, we draw attention to T. lenti and suggest that although new analyzes should be performed, possibly this species is the sixth member of the T. brasiliensis complex.

Triatominae are widely recognised for their role as vectors of Trypanosoma cruzi. One of the main biological characteristics of this subfamily is their obligate haematophagous condition. However, previous studies on Belminus herreri and Belminus ferroae suggested that cockroaches are their principal hosts in domiciles. Due to this peculiar behaviour, the aim of this study was to analyse several demographic and reproductive parameters of B. ferroae fed on three different hosts (mice, cockroaches and Rhodnius prolixus) and relate B. ferroae fitness to these alternative hosts. The cohorts were reared under constant conditions. The egg hatching rate was similar for cohorts fed on cockroaches (69.4%) and R. prolixus (63.8%), but was much lower for the cohort fed on mice (16%). The development time from the nymph to adult stage and the average age of first reproduction (α) presented lower values in the cohort fed on cockroaches, which is consistent with the higher population growth rate associated with this host. Demographic parameters [intrinsic rate of natural increase, finite rate of population growth, net reproductive rate and damping ratio] showed statistically significant differences between the cohorts. Analysis of the life history of B. ferroae revealed a higher fitness related to the cockroach. The implications of these results for the origin of the subfamily are discussed.

The host-vector-parasite interactions in Chagas disease peridomestic transmission cycles in the United States are not yet well understood. Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) infection prevalence and bloodmeal sources were determined for adult and immature triatomine (Hemiptera: Reduviidae) specimens collected from residential settings in central Texas. Sequenced cytochrome b DNA segments obtained from triatomine digestive tract identified nine vertebrate hosts and one invertebrate host in four triatomine species (Triatoma gerstaeckeri, Triatoma indictiva, Triatoma protracta, and Triatoma sanguisuga). The broad range of wild and domestic host species detected in triatomine specimens collected from residential sites indicates high host diversity and potential movement between the sylvatic and peridomestic settings. Domestic dogs appear to be key in the maintenance of the peridomestic transmission cycle as both a blood host for the triatomine vectors and a potential reservoir for the parasite. The high rate of T. cruzi infection among triatomine specimens that were collected from inside houses, outside houses, and dog kennels (69, 81, and 82%, respectively) suggests a current risk for Chagas disease vector-borne transmission for humans and domestic animals in residential settings in Texas because of overlap with the sylvatic cycle.

Chagas disease, which is caused by the parasite Trypanosoma cruzi, is transmitted to humans by blood-sucking bugs (Triatominae). Eratyrus mucronatus is a well-dispersed triatomine species, found sometimes in dwellings. In the Apolo region of Bolivia, people continue to complain of bites by this bug despite five years of chemical control. For the first time, the domiciliation process of E. mucronatus was evaluated in a zone treated by insecticide, and it was compared with a previous situation 14 years ago. Both an entomological and a serological study were carried out: 152 dwellings were visited and 491 blood samples were analyzed with Stat-Pack and ELISA tests. In 34 dwellings (23% of the total visited dwellings), 160 triatomines of all stages were collected belonging to two species, E. mucronatus (98% of the capture) and Panstrongylus geniculatus. A domiciliation of E. mucronatus is demonstrated, particularly in the peridomicile. Bugs were captured more frequently in bedrooms in the intradomicile, and in curahuas (boundary walls in rammed mud) in the peridomicile. A P. geniculatus adult was found infected with T. cruzi. No evidence of a local vectorial transmission was found. In particular, the limited effect of the insecticide on the presence of E. mucronatus and the role of the curahuas as a source of intrusion/domiciliation process are discussed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

To determine the infestation and trypanosome infection of triatomines captured in Mauritia flexuosa palm trees across its geographic distribution in the Brazilian savanna (Cerrado), we sampled 42 localities in eight states and in the Federal District, Brazil, between July 2005 and January 2010. Overall, 2154 specimens of the species Rhodnius neglectus, Psammolestes tertius, Triatoma sordida, and Microtriatoma borbai, were collected. Among the 341 palms sampled, 182 (53.3%) were infested with R. neglectus, which resulted in the capture of 1639 specimens (9.0 insects per infested palm). P. tertius occurred in 26 palms (8%), which resulted in the capture of 484 specimens (19 insects per infested palm). T. sordida (n=30) and M. borbai (n=1) occurred in only one location. From 537 R. neglectus examined, 44 were infected (8%) with Trypanosoma rangeli and/or Trypanosoma cruzi (Tc Id). M. flexuosa was previously recognized as a suitable breeding ecotope for R. neglectus in the Brazilian states of Minas Gerais, Goiás, Tocantins and the Federal District. Our results expand this distribution to other states (São Paulo, Bahia, Mato Grosso, Maranhão and Piauí), and also show that this particular palm tree harbors other triatomine species. Finally, we show that R. neglectus plays an important role in maintaining the enzootic circulation of T. cruzi and T. rangeli in the Brazilian savanna., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Vector control has substantially reduced Chagas disease (ChD) incidence. However, transmission by household-reinfesting triatomines persists, suggesting that entomological surveillance should play a crucial role in the long-term interruption of transmission. Yet, infestation foci become smaller and harder to detect as vector control proceeds, and highly sensitive surveillance methods are needed. Community participation (CP) and vector-detection devices (VDDs) are both thought to enhance surveillance, but this remains to be thoroughly assessed., Methodology/principal Findings: We searched Medline, Web of Knowledge, Scopus, LILACS, SciELO, the bibliographies of retrieved studies, and our own records. Data from studies describing vector control and/or surveillance interventions were extracted by two reviewers. Outcomes of primary interest included changes in infestation rates and the detection of infestation/reinfestation foci. Most results likely depended on study- and site-specific conditions, precluding meta-analysis, but we re-analysed data from studies comparing vector control and detection methods whenever possible. Results confirm that professional, insecticide-based vector control is highly effective, but also show that reinfestation by native triatomines is common and widespread across Latin America. Bug notification by householders (the simplest CP-based strategy) significantly boosts vector detection probabilities; in comparison, both active searches and VDDs perform poorly, although they might in some cases complement each other., Conclusions/significance: CP should become a strategic component of ChD surveillance, but only professional insecticide spraying seems consistently effective at eliminating infestation foci. Involvement of stakeholders at all process stages, from planning to evaluation, would probably enhance such CP-based strategies.

We present an overview of the two main strategies for the primary (vector control) and secondary (patient care) prevention of Chagas disease (CD). We identify major advances, knowledge gaps, and key research needs in both areas. Improved specific chemotherapy, including more practical formulations (e.g., paediatric) or combinations of existing drugs, and a better understanding of pathogenesis, including the relative weights of parasite and host genetic makeup, are clearly needed. Regarding CD vectors, we find that only about 10-20% of published papers on triatomines deal directly with disease control. We pinpoint the pitfalls of the current consensus on triatomine systematics, particularly within the Triatomini, and suggest how some straightforward sampling and analytical strategies would improve research on vector ecology, naturally leading to sounder control-surveillance schemes. We conclude that sustained research on CD prevention is still crucial. In the past, it provided not only the know-how, but also the critical mass of scientists needed to foster and consolidate CD prevention programmes; in the future, both patient care and long-term vector control would nonetheless benefit from more sharply focused, problem-oriented research., (2010 Elsevier B.V. All rights reserved.)

Background: The developmental time of vector insects is important in population dynamics, evolutionary biology, epidemiology and in their responses to global climatic change. In the triatomines (Triatominae, Reduviidae), vectors of Chagas disease, evolutionary ecology concepts, which may allow for a better understanding of their biology, have not been applied. Despite delay in the molting in some individuals observed in triatomines, no effort was made to explain this variability., Methodology: We applied four methods: (1) an e-mail survey sent to 30 researchers with experience in triatomines, (2) a statistical description of the developmental time of eleven triatomine species, (3) a relationship between development time pattern and climatic inter-annual variability, (4) a mathematical optimization model of evolution of developmental delay (diapause)., Principal Findings: 85.6% of responses informed on prolonged developmental times in 5(th) instar nymphs, with 20 species identified with remarkable developmental delays. The developmental time analysis showed some degree of bi-modal pattern of the development time of the 5(th) instars in nine out of eleven species but no trend between development time pattern and climatic inter-annual variability was observed. Our optimization model predicts that the developmental delays could be due to an adaptive risk-spreading diapause strategy, only if survival throughout the diapause period and the probability of random occurrence of "bad" environmental conditions are sufficiently high., Conclusions/significance: Developmental delay may not be a simple non-adaptive phenotypic plasticity in development time, and could be a form of adaptive diapause associated to a physiological mechanism related to the postponement of the initiation of reproduction, as an adaptation to environmental stochasticity through a spreading of risk (bet-hedging) strategy. We identify a series of parameters that can be measured in the field and laboratory to test this hypothesis. The importance of these findings is discussed in terms of global climatic change and epidemiological consequences.

One important paradigm in host-parasite evolutionary biology is the ability of parasites to manipulate the phenotype of their hosts to facilitate transmission. In this paper, I examine whether the protozoan parasite Trypanosoma cruzi modifies the developmental time, body size, and survival of its vector, the bloodsucking insect Mepraia spinolai (Hemiptera; Reduviidae). M. spinolai nymphs were experimentally infected when fed on T. cruzi-infected mice (infected group) or kept uninfected when fed on healthy mice (control group). T. cruzi-infected insects showed a retarded developmental time and reduced survival compared with uninfected individuals. The impact of the parasite on the vector was age-dependent as the last three insect molts were the most affected stages. The presence of T. cruzi decreased significantly the weight of male and female insects in the three last stages. When insect sex was taken into account, infected female bugs took longer than infected males to develop into the adult stage, which implies that the impact of T. cruzi is sex-dependent. Results from this study indicate that T. cruzi has a strong impact on life history traits of M. spinolai and provide strong evidence of age- and sex-dependent parasite-induced phenotype modification for insect vectors. The implications of this study along with previously reported feeding behavioral alterations in this insect vector-parasite system suggest that T. cruzi-induced modifications could translate into an enhanced transmission to definitive mammal hosts.

The associations between the presence of triatomines and environmental variables were studied using correlation analysis and logistic regression models for a sample of villages in the south-eastern provinces of Guatemala. Information on the presence of Triatoma dimidiata, T. nitida and Rhodnius prolixus came from entomological surveys carried out by the Ministry of Health of Guatemala as part of its vector control programme. Environmental information for each village was extracted from digital thematic maps developed by the Ministry of Agriculture. The presence of T. nitida was found to be significantly associated with the average minimum temperature. The odds of presence of T. nitida in a village decreased as the average minimum temperature increased. T. nitida exists at altitudes above 1000 m above sea level in temperate regions. The presence of R. prolixus showed a significant positive association with maximum absolute temperature and relative humidity. The logistic regression model for R. prolixus showed a good fit and predicted suitable habitats in the provinces of Chiquimula, Zacapa and Jalapa, which agrees with the known distribution of the species. Habitat partitioning between R. prolixus and T. dimidiata is suggested by their significant and opposite associations with maximum absolute temperature. Improved models to predict suitable habitats for T. dimidiata hold promise for spatial targeting of integrated vector management.

Few studies on the relationship between environmental factors and Trypanosoma cruzi transmission have been conducted in Ecuador. We conducted a cross-sectional study of household risk factors for T. cruzi seropositivity in 2 distinct geographical regions of Ecuador. Exposure information was collected via household surveys, and subjects were tested for serological evidence of T. cruzi infection. In total, 3,286 subjects from 997 households were included. In the coastal region, factors associated with seropositivity were living in a house with a palm roof (odds ratio [OR] = 2.63, 95% confidence interval, [1.61. 4.27]), wood walls (OR = 5.75 [2.04, 16.18]), or cane walls (OR = 2.81 11.31, 6.04]), and the presence of firewood in the peridomicile (OR = 2.48 [1.54, 4.01]). Accumulation of trash outside the home was associated with a reduced risk of seropositivity (OR = 0.25 [0.12, 0.51]). In the Andean region, living in a house with adobe walls was the only factor predictive of T. cruzi seropositivity. In conclusion, risk factors for T. cruzi transmission in Ecuador varied by geographic region, probably because of differing behavior of the triatomine vector species in each region. An understanding of the transmission dynamics of T. cruzi in a particular area is necessary for the development of effective Chagas disease control strategies in those areas.

Granite rocks is a very abundant material in Mexico because they are used habitually as borders for fields. The current work established the significance of this ecotype as a colonization site for triatomines of the Phyllosoma complex. Seven sites, arbitrary selected, in San Martin de Hidalgo municipality (Mexico) were investigated in April 2002 by using 210 mouse bait-traps left during the night in wall hollows. One hundred and seventy-two triatomines of all life stages were collected from the seven sites. Triatomines adhered to the tape that covered the traps or were found near them, and 36.6% of the traps collected triatomines. The principal species was Triatomia longipennis Usinger (1939) and low numbers of Triatoma picturata Usinger (1939) were found. The nymphal population was very young, probably corresponding to the reproductive period in April (end of the dry season). The infection rate of the triatomines for Trypanosoma cruzi was 49%. Because collecting triatomines in the field is laborious and time-consuming, the mouse bait-trap method found to be practical to assess the population of triatomines within a sylvatic habitat.

Aspects related to hatching, time-lapse between presenting the blood-meal and beginning of feeding, feeding time, postfeed defecation delay, mortality, and fecundity for each stage of Meccus longipennis life-cycle were evaluated. The bugs were maintained in a dark incubator at 27 1 C and 80 5% rh, were fed weekly and checked daily for ecdysis or death. The hatching rate observed for 300 eggs was 76.7% and the average time of hatching was 19.8 days. Mean time-lapse between presentation of the blood meal and the beginning of feeding was under 5 min in nymphal stages and postfeed defecation delay was under 10 min in most stages, except in fourth and fifth stages. Mean feeding time was longer than 10 min in most stages, except in fourth stage. One hundred thirty-one nymphs (N) (65.5%) completed the cycle and the average time from NI to adult was 192.6 34.8 days. The average span in days for each stage was 18.1 for NI, 21.4 for NII, 29.5 for NIII, 45.5 for NIV and 55.9 for NV. The number of bloodmeals at each nymphal stage varied from 1 to 5. The mortality rate was 3.29 for NI, 6.8 for NII, 2.92 for NIII 3.76 for NIV, and 10.16 for NV nymphs. The average number of eggs laid per female in a 9-month period was 615.6. Based on our results, we conclude that M. longipennis has some biological and behavioral characteristics which influence its capacity of becoming infected and transmitting Trypanosoma cruzi to human populations in those areas of Mexico where it is currently present.

Aspects related to hatching, time-lapse between presenting the blood meal and beginning of feeding, feeding time, postfeed defecation delay,life time, mortality and fecundity for each stage of Meccus picturatus, life-cycle were evaluated and compared in two cohorts of M. picturatus fed on hens or rabbits. The hatching rate observed for each of the two studied groups of eggs was 78.1% (n = 2298) on the group fed on hens and 82.1% (n = 2704) on that fed on rabbits, and the average time of hatching was 20 days. Mean time-lapse for beginning feeding was under 3 min in nymphal stages and postfeed defecation delay was under 10 min in all stages, in both cohorts. Mean feeding time was significantly (P < 0.05) shorter in triatomines fed on hens than on rabbits. A similar number of nymphs of each cohort, 69 fed on hens (34.5%) and 68 fed on rabbits (34%), completed the cycle. No significantly (P > 0.05) differences were recorded among the average times from NI to adult in the cohort fed on hens (196.8 15.8 days) and the average time in the cohort fed on rabbits (189.5 22.9). The average span in days for each stage fed on hens was not significantly different to the average span for each stage fed on rabbits. The number of blood meals at each nymphal stage varied from 1 to 6 in both cohorts. The mortality rates were higher on fifth nymphal stage, in both cohorts. No significant (P > 0.05) differences were recorded on mortality rates on most nymphal stages of both cohorts. The average number of eggs laid per female from the cohort fed on hens in a 9-month period was 791.1, whereas the average number of eggs in the cohort fed on rabbits was 928.3.

In July 2000, Heads of State of the 36th Session of the Organisation for African Unity signed a potentially important declaration on African trypanosomiasis, urging member states "to act collectively to rise to the challenge of eliminating the problem through concerted efforts in mobilising the necessary human, financial and material resources required to render Africa tsetse-free within the shortest time possible". To many, such an ambitious dream is received with some scepticism, recalling the doubts that surrounded a similar declaration signed in Brasilia in 1991, which paved the way for the Southern Cone Initiative against American trypanosomiasis (Chagas disease). True, the two diseases are quite different. But the operational challenges are quite similar, and there are sufficient biological parallels to suggest that the Latin American experience in controlling Chagas disease may provide a useful model for the control of African trypanosomiasis.

Applied topically to larvae of Rhodnius prolixus Stal, Triatoma infestans (Klug) and Panstrongylus herreri Wygodzinsky, vectors of Trypanosoma cruzi, the causative agent of Chagas' disease, a synthetic, furan-containing anti-juvenile hormonal compound, 2-(2-ethoxyethoxy)ethyl furfuryl ether induced a variety of biomorphological alterations, including precocious metamorphosis into small adultoids with adult abdominal cuticle, ocelli, as well as rudimentary adultoid wings. Some adultoids died during ecdysis and were confined within the old cuticle. The extension of these biomorphological responses is discussed in terms of the complexity of the action of anti-juvenile hormonal compounds during the development of triatomines.

Intending to provide new parameters to be used in Triatomines' Taxonomy, vectors of Chaga's Disease and to amplify a large range of knowledge about this species, a study of the structure of the egg and external morphology of the five nymphal instars was done. The eggs show under optical microscope (M.O.), the chorium's surface of the body and the operculum formed by poligonal areas, clearer under scanning electronic microscope (MEV). The apex of the third rostrum segment in all 5 instars nymphs, show 1 + 1 invaginated and elongated structures and the apical portion of the second tarsal segment presents a group of more or less numerous, very long, delicated and golden hairs.

The effects of azadirachtin, a tetranortriterpenoid from the neem tree Azadirachta indica J., on both immunity and Trypanosoma cruzi interaction within Rhodnius prolixus and other triatomines, were presented. Given through a blood meal, azadirachtin affected the immune reactivity as shown by a significant reduction in numbers of hemocytes and consequently nodule formation following challenge with Enterobacter cloacae beta 12, reduction in ability to produce antibacterial activities in the hemolymph when injected with bacteria, and decreased ability to destroy the infection caused by inoculation of E. cloacae cells. A single dose of azadirachtin was able to block the development of T. cruzi in R. prolixus if given through the meal at different intervals, together with, before or after parasite infection. Similarly, these results were observed with different triatomine species and different strains of T. cruzi. Azadirachtin induced a permanent resistance of the vector against reinfection with T. cruzi. The significance of these data is discussed in relation to the general mode of azadirachtin action in insects.

A population dynamics study of D. maximus was carried out under laboratory conditions (28 degrees C e 65% +/- 5% U.R.), and the methodology was the same that has been used for rearing these insects. In order to evaluate the population growth rate of this species, during a 24 months period, five colonies started with a couple recently emerged were observed. Each couple (a male and a female) was maintained in a glass container measuring 20 cm of diameter and 20 cm in height with filter paper on the bottom. The insects were monthly feeding with normal mice blood, and at this day the number of eggs, nymphal stages and adults was registered. All graphical representations of the populations growth showed the same shape. It was found that the average of nymphal stage represented 64.3% of the holè population whereas the oviposition curve showed to be inverse to this one (28.57%) a small percentage of adults was found: males 3.85% and females 3.12%. In this study observations on the biological cycle, longevity and fertility rates were also carried out.

In order to simplify breeding of triatominae in the laboratory, for performing xenodiagnosis and other biologic studies, we tried to feed the insects "in vitro" with citrated or defibrinated blood from commercially abated chicken. Two types of efficacy observations were carried out with Triatoma infestans: a) analysis of the chaining of successive nymphal stages, viability of satisfactory matching, fertile oviposition and adequate reproduction; b) assessment of viability and infectivity of Trypanosoma cruzi in the insects. As a conclusion, it became evident that, despite operational easiness, the objectives were not achieved, since the classical procedure used as the control, was always superior.

1. Topical application of the proallatotoxin ethoxyprecocene II (60 micrograms/nymph) to 4th-instar nymphs of Rhodnius prolixus at various times before and after a blood meal induced precocious metamorphosis. 2. The highest percentage of adultoids was obtained when proallatotoxin was applied prior to feeding or up to day 3 after the blood meal. 3. The proallatotoxin-sensitive period ended 4 days after feeding just before the maximum peak of ecdysteroid concentration in the hemolymph. 4. The significance of these findings is discussed in terms of the juvenile hormone-sensitive period and the hormonal program which controls molting in this insect.

The specialized cell types and two distinct regions of the adult Rhodnius prolixus cement gland develop from a simple pseudostratified epithelial tube during the 20-22 days of the fifth stadium. Feeding initiates the first phase, proliferation. Cells round up and divide tangentially to the lumen. Following the proliferation phase, differentiative mitoses occur and differentiation, resulting in secretory units (consisting of a ductule, gland cell and cuticular lining), ensues in the distal region. Ductule morphogenesis occurs without pseudocilia, thus differing from other insect glands. The complex changes in cell shape and interaction occur during development of the secretory unit. The secretory cell and end-apparatus develop from a double cell unit at the base of elongating ductules. The inner cell produces a complex end-apparatus of epicuticle that mirrors the microvillar pattern and then it degenerates. The ductules are lined by cuticulin and inner epicuticle while the central gland lumen has a layer of endocuticle as well. The epithelium of the proximal region remains simple producing the thick corrugated cuticle characteristic of the adult secretory duct. The mesodermal covering forms a thick longitudinal striated muscle layer that adheres to the epithelium via desmosomes.