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1.
Chagas disease, in the Amazon Region as elsewhere, can be considered an enzootic disease of wild animals or an anthropozoonosis, an accidental disease of humans that is acquired when humans penetrate a wild ecosystem or when wild triatomines invade human dwellings attracted by light or searching for human blood. The risk of endemic Chagas disease in the Amazon Region is associated with the following phenomena: (i) extensive deforestation associated with the displacement of wild mammals, which are the normal sources of blood for triatomines, (ii) adaptation of wild triatomines to human dwellings due to the need for a new source of blood for feeding and (iii) uncontrolled migration of human populations and domestic animals that are already infected with Trypanosoma cruzi from areas endemic for Chagas disease to the Amazon Region. Several outbreaks of severe acute cases of Chagas disease, as well as chronic cases, have been described in the Amazon Region. Control measures targeted to avoiding endemic Chagas disease in the Amazon Region should be the following: improving health education in communities, training public health officials and communities for vector and Chagas disease surveillance and training local physicians to recognise and treat acute and chronic cases of Chagas diseases as soon as possible. 相似文献
2.
WM Monteiro LK Magalhães AR de Sá ML Gomes MJ Toledo L Borges I Pires JA de Oliveira Guerra H Silveira Md Barbosa 《PloS one》2012,7(7):e41284
Background
Chagas disease is an emergent tropical disease in the Brazilian Amazon Region, with an increasing number of cases in recent decades. In this region, the sylvatic cycle of Trypanosoma cruzi transmission, which constitutes a reservoir of parasites that might be associated with specific molecular, epidemiological and clinical traits, has been little explored. The objective of this work is to genetically characterize stocks of T. cruzi from human cases, triatomines and reservoir mammals in the State of Amazonas, in the Western Brazilian Amazon.Methodology/Principal Findings
We analyzed 96 T. cruzi samples from four municipalities in distant locations of the State of Amazonas. Molecular characterization of isolated parasites from cultures in LIT medium or directly from vectors or whole human blood was performed by PCR of the non-transcribed spacer of the mini-exon and of the 24 S alfa ribosomal RNA gene, RFLP and sequencing of the mitochondrial cytochrome c oxidase subunit II (COII) gene, and by sequencing of the glucose-phosphate isomerase gene. The T. cruzi parasites from two outbreaks of acute disease were all typed as TcIV. One of the outbreaks was triggered by several haplotypes of the same DTU. TcIV also occurred in isolated cases and in Rhodnius robustus. Incongruence between mitochondrial and nuclear phylogenies is likely to be indicative of historical genetic exchange events resulting in mitochondrial introgression between TcIII and TcIV DTUs from Western Brazilian Amazon. TcI predominated among triatomines and was the unique DTU infecting marsupials.Conclusion/Significance
DTU TcIV, rarely associated with human Chagas disease in other areas of the Amazon basin, is the major strain responsible for the human infections in the Western Brazilian Amazon, occurring in outbreaks as single or mixed infections by different haplotypes. 相似文献3.
Samanta Cristina das Chagas Xavier André Luiz Rodrigues Roque Daniele Bilac Vitor Ant?nio Louzada de Araújo Sócrates Fraga da Costa Neto Elias Seixas Lorosa Luiz Felipe Coutinho Ferreira da Silva Ana Maria Jansen 《PLoS neglected tropical diseases》2014,8(5)
Background
The new epidemiological scenario of orally transmitted Chagas disease that has emerged in Brazil, and mainly in the Amazon region, needs to be addressed with a new and systematic focus. Belém, the capital of Pará state, reports the highest number of acute Chagas disease (ACD) cases associated with the consumption of açaí juice.Methodology/Principal Findings
The wild and domestic enzootic transmission cycles of Trypanosoma cruzi were evaluated in the two locations (Jurunas and Val-de Cães) that report the majority of the autochthonous cases of ACD in Belém city. Moreover, we evaluated the enzootic cycle on the three islands that provide most of the açaí fruit that is consumed in these localities. We employed parasitological and serological tests throughout to evaluate infectivity competence and exposure to T. cruzi. In Val-de-Cães, no wild mammal presented positive parasitological tests, and 56% seroprevalence was observed, with low serological titers. Three of 14 triatomines were found to be infected (TcI). This unexpected epidemiological picture does not explain the high number of autochthonous ACD cases. In Jurunas, the cases of ACD could not be autochthonous because of the absence of any enzootic cycle of T. cruzi. In contrast, in the 3 island areas from which the açaí fruit originates, 66.7% of wild mammals and two dogs displayed positive hemocultures, and 15.6% of triatomines were found to be infected by T. cruzi. Genotyping by mini-exon gene and PCR-RFLP (1f8/Akw21I) targeting revealed that the mammals and triatomines from the islands harbored TcI and Trypanosoma rangeli in single and mixed infections.Conclusion/Significance
These findings show that cases of Chagas disease in the urban area of Belém may be derived from infected triatomines coming together with the açaí fruits from distant islands. We term this new epidemiological feature of Chagas disease as “Distantiae transmission”. 相似文献4.
José Rodrigues Coura 《Memórias do Instituto Oswaldo Cruz》2013,108(8):962-967
From an epidemiological point of view, Chagas disease and its reservoirs and vectors
can present the following characteristics: (i) enzooty, maintained by wild animals
and vectors, with broad occurrence from southern United States of America (USA) to
southern Argentina and Chile (42ºN 49ºS), (ii) anthropozoonosis, when man invades the
wild ecotope and becomes infected with Trypanosoma cruzi from wild
animals or vectors or when the vectors and wild animals, especially marsupials,
invade the human domicile and infect man, (iii) zoonosis-amphixenosis and exchanged
infection between animals and humans by domestic vectors in endemic areas and (iv)
zooanthroponosis, infection that is transmitted from man to animals, by means of
domestic vectors, which is the rarest situation in areas endemic for Chagas disease.
The characteristics of Chagas disease as an enzooty of wild animals and as an
anthropozoonosis are seen most frequently in the Brazilian Amazon and in the
Pan-Amazon region as a whole, where there are 33 species of six genera of wild
animals: Marsupialia, Chiroptera, Rodentia, Edentata (Xenarthra), Carnivora and
Primata and 27 species of triatomines, most of which infected with T.
cruzi . These conditions place the resident populations of this area or
its visitors - tourists, hunters, fishermen and especially the people whose
livelihood involves plant extraction - at risk of being affected by Chagas disease.
On the other hand, there has been an exponential increase in the acute cases of
Chagas disease in that region through oral transmission of T. cruzi
, causing outbreaks of the disease. In four seroepidemiological surveys that were
carried out in areas of the microregion of the Negro River, state of Amazonas, in
1991, 1993, 1997 and 2010, we found large numbers of people who were serologically
positive for T. cruzi infection. The majority of them and/or their
relatives worked in piassava extraction and had come into contact with and were stung
by wild triatomines in that area. Finally, a characteristic that is greatly in
evidence currently is the migration of people with Chagas disease from endemic areas
of Latin America to non-endemic countries. This has created a new dilemma for these
countries: the risk of transmission through blood transfusion and the onus of
controlling donors and treating migrants with the disease. As an enzooty of wild
animals and vectors, and as an anthropozoonosis, Chagas disease cannot be eradicated,
but it must be controlled by transmission elimination to man. 相似文献
5.
Valdirene dos Santos Lima Samanta Cristina das Chagas Xavier Irene Fabíola Roman Maldonado André Luiz Rodrigues Roque Ana Carolina Paulo Vicente Ana Maria Jansen 《PloS one》2014,9(12)
Trypanosoma cruzi infection is a complex sylvatic enzooty involving a wide range of animal species. Six discrete typing units (DTUs) of T. cruzi, named TcI to TcVI, are currently recognized. One unanswered question concerning the epidemiology of T. cruzi is the distribution pattern of TcII and hybrid DTUs in nature, including their virtual absence in the Brazilian Amazon, the current endemic area of Chagas disease in Brazil. Herein, we characterized biological samples that were collected in previous epizootiological studies carried out in the Amazon Basin in Brazil. We performed T. cruzi genotyping using four polymorphic genes to identify T. cruzi DTUs: mini-exon, 1f8, histone 3 and gp72. This analysis was conducted in the following biological samples: (i) two T. cruzi isolates obtained by culturing of stools from the triatomine species Rhodnius picttipes and (ii) five serum samples from dogs in which trypomastigotes were observed during fresh blood examination. We report for the first time the presence of TcII and hybrid DTUs (TcV/TcVI) in the Amazon region in mixed infections with TcI. Furthermore, sequencing of the constitutive gene, gp72, demonstrated diversity in TcII even within the same forest fragment. These data show that TcII is distributed in the five main Brazilian biomes and is likely more prevalent than currently described. It is very probable that there is no biological or ecological barrier to the transmission and establishment of any DTU in any biome in Brazil. 相似文献
6.
José Rodrigues Coura Pedro Albajar Vi?as Angela CV Junqueira 《Memórias do Instituto Oswaldo Cruz》2014,109(7):856-862
Chagas disease is maintained in nature through the interchange of three cycles: the
wild, peridomestic and domestic cycles. The wild cycle, which is enzootic, has
existed for millions of years maintained between triatomines and wild mammals. Human
infection was only detected in mummies from 4,000-9,000 years ago, before the
discovery of the disease by Carlos Chagas in 1909. With the beginning of
deforestation in the Americas, two-three centuries ago for the expansion of
agriculture and livestock rearing, wild mammals, which had been the food source for
triatomines, were removed and new food sources started to appear in peridomestic
areas: chicken coops, corrals and pigsties. Some accidental human cases could also
have occurred prior to the triatomines in peridomestic areas. Thus, triatomines
progressively penetrated households and formed the domestic cycle of Chagas disease.
A new epidemiological, economic and social problem has been created through the
globalisation of Chagas disease, due to legal and illegal migration of individuals
infected by Trypanosoma cruzi or presenting Chagas disease in its
varied clinical forms, from endemic countries in Latin America to non-endemic
countries in North America, Europe, Asia and Oceania, particularly to the United
States of America and Spain. The main objective of the present paper was to present a
general view of the interchanges between the wild, peridomestic and domestic cycles
of the disease, the development of T. cruzi among triatomine, their
domiciliation and control initiatives, the characteristics of the disease in
countries in the Americas and the problem of migration to non-endemic countries. 相似文献
7.
Natália Spitz Francisco CA Mello Natalia Motta Araujo 《Memórias do Instituto Oswaldo Cruz》2015,110(1):151-153
The Brazilian Amazon Region is a highly endemic area for hepatitis B virus (HBV).
However, little is known regarding the genetic variability of the strains circulating
in this geographical region. Here, we describe the first full-length genomes of HBV
isolated in the Brazilian Amazon Region; these genomes are also the first complete
HBV subgenotype D3 genomes reported for Brazil. The genomes of the five Brazilian
isolates were all 3,182 base pairs in length and the isolates were classified as
belonging to subgenotype D3, subtypes ayw2 (n = 3) and ayw3 (n = 2). Phylogenetic
analysis suggested that the Brazilian sequences are not likely to be closely related
to European D3 sequences. Such results will contribute to further epidemiological and
evolutionary studies of HBV. 相似文献
8.
Two of the major problems facing the Amazon - human migration from the other areas and uncontrolled deforestation - constitute the greatest risk for the establishment of endemic Chagas disease in this part of Brazil. At least 18 species of triatomines had been found in the Brazilian Amazon, 10 of them infected with Trypanosoma cruzi, associated with numerous wild reservoirs. With wide-range deforestation, wild animals will perforce be driven into other areas, with tendency for triatomines to become adapted to alternative food sources in peri and intradomicilies. Serological surveys and cross-sectional studies for Chagas disease, carried out in rural areas of the Rio Negro, in the Brazilian Amazon, showed a high level of seropositivity for T. cruzi antibodies. A strong correlation of seroreactivity with the contact of gatherers of pia?ava fibers with wild triatomines could be evidenced. 相似文献
9.
Wuelton Marcelo Monteiro Ana Paula Margioto Teston Ana Paula Gruendling Daniele dos Reis M?nica Lúcia Gomes Silvana Marques de Araújo Maria Terezinha Bahia Laylah Kelre Costa Magalh?es Jorge Augusto de Oliveira Guerra Henrique Silveira Max Jean de Ornelas Toledo Maria das Gra?as Vale Barbosa 《PLoS neglected tropical diseases》2013,7(2)
Background
In the Brazilian Amazon, clinical and epidemiological frameworks of Chagas disease are very dissimilar in relation to the endemic classical areas of transmission, possibly due to genetic and biological characteristics of the circulating Trypanosoma cruzi stocks. Twenty six T. cruzi stocks from Western Amazon Region attributed to the TcI and TcIV DTUs were comparatively studied in Swiss mice to test the hypothesis that T. cruzi clonal structure has a major impact on its biological and medical properties.Methodology/Principal Findings
Seventeen parameters were assayed in mice infected with 14 T. cruzi strains belonging to DTU TcI and 11 strains typed as TcIV. In comparison with TcI, TcIV stocks promoted a significantly shorter pre-patent period (p<0.001), a longer patent period (p<0.001), higher values of mean daily parasitemia (p = 0.009) and maximum of parasitemia (p = 0.015), earlier days of maximum parasitemia (p<0.001) and mortality (p = 0.018), higher mortality rates in the acute phase (p = 0.047), higher infectivity rates (p = 0.002), higher positivity in the fresh blood examination (p<0.001), higher positivity in the ELISA at the early chronic phase (p = 0.022), and a higher positivity in the ELISA at the late chronic phase (p = 0.003). On the other hand TcI showed higher values of mortality rates in the early chronic phase (p = 0.014), higher frequency of mice with inflammatory process in any organ (p = 0.005), higher frequency of mice with tissue parasitism in any organ (p = 0.027) and a higher susceptibility to benznidazole (p = 0.002) than TcIV. Survival analysis showing the time elapsed from the day of inoculation to the beginning of the patent period was significantly shorter for TcIV strains and the death episodes triggered following the infection with TcI occurred significantly later in relation to TcIV. The notable exceptions come from positivity in the hemocultures and PCR, for which the results were similar.Conclusion/Significance
T. cruzi stocks belonging to TcI and TcIV DTUs from Brazilian Amazon are divergent in terms of biological and medical properties in mice. 相似文献10.
Azael Salda?a José E Calzada Vanessa Pineda Milixa Perea Chystrie Rigg Kadir González Ana Maria Santamaria Nicole L Gottdenker Luis F Chaves 《Memórias do Instituto Oswaldo Cruz》2015,110(7):936-944
Chagas disease, caused by Trypanosoma cruzi infection, is a zoonosis
of humans, wild and domestic mammals, including dogs. In Panama, the main T.
cruzi vector is hodnius pallescens, a triatomine bug
whose main natural habitat is the royal palm, Attalea butyracea. In
this paper, we present results from three T. cruzi serological tests
(immunochromatographic dipstick, indirect immunofluorescence and ELISA) performed in
51 dogs from 24 houses in Trinidad de Las Minas, western Panama. We found that nine
dogs were seropositive (17.6% prevalence). Dogs were 1.6 times more likely to become
T. cruzi seropositive with each year of age and 11.6 times if
royal palms where present in the peridomiciliary area of the dog''s household or its
two nearest neighbours. Mouse-baited-adhesive traps were employed to evaluate 12
peridomestic royal palms. All palms were found infested with R.
pallescens with an average of 25.50 triatomines captured per palm. Of 35
adult bugs analysed, 88.6% showed protozoa flagellates in their intestinal contents.
In addition, dogs were five times more likely to be infected by the presence of an
additional domestic animal species in the dog''s peridomiciliary environment. Our
results suggest that interventions focused on royal palms might reduce the exposure
to T. cruzi infection. 相似文献
11.
Aguilar HM Abad-Franch F Dias JC Junqueira AC Coura JR 《Memórias do Instituto Oswaldo Cruz》2007,102(Z1):47-56
The risk that Chagas disease becomes established as a major endemic threat in Amazonia (the world's largest tropical biome, today inhabited by over 30 million people) relates to a complex set of interacting biological and social determinants. These include intense immigration from endemic areas (possibly introducing parasites and vectors), extensive landscape transformation with uncontrolled deforestation, and the great diversity of wild Trypanosoma cruzi reservoir hosts and vectors (25 species in nine genera), which maintain intense sylvatic transmission cycles. Invasion of houses by adventitious vectors (with infection rates > 60%) is common, and focal adaptation of native triatomines to artificial structures has been reported. Both acute (approximately 500) and chronic cases of autochthonous human Chagas disease have been documented beyond doubt in the region. Continuous, low-intensity transmission seems to occur throughout the Amazon, and generates a hypoendemic pattern with seropositivity rates of approximately 1-3%. Discrete foci also exist in which transmission is more intense (e.g., in localized outbreaks probably linked to oral transmission) and prevalence rates higher. Early detection-treatment of acute cases is crucial for avoiding further dispersion of endemic transmission of Chagas disease in Amazonia, and will require the involvement of malaria control and primary health care systems. Comprehensive eco-epidemiological research, including prevalence surveys or the characterization of transmission dynamics in different ecological settings, is still needed. The International Initiative for Chagas Disease Surveillance and Prevention in the Amazon provides the framework for building up the political and scientific cooperation networks required to confront the challenge of preventing Chagas disease in Amazonia. 相似文献
12.
Janine M Ramsey A Townsend Peterson Oscar Carmona-Castro David A Moo-Llanes Yoshinori Nakazawa Morgan Butrick Ezequiel Tun-Ku Keynes de la Cruz-Félix Carlos N Ibarra-Cerde?a 《Memórias do Instituto Oswaldo Cruz》2015,110(3):339-352
Chagas disease is one of the most important yet neglected parasitic diseases in
Mexico and is transmitted by Triatominae. Nineteen of the 31 Mexican triatomine
species have been consistently found to invade human houses and all have been found
to be naturally infected with Trypanosoma cruzi. The present paper
aims to produce a state-of-knowledge atlas of Mexican triatomines and analyse their
geographic associations with T. cruzi, human demographics and
landscape modification. Ecological niche models (ENMs) were constructed for the 19
species with more than 10 records in North America, as well as for T.
cruzi. The 2010 Mexican national census and the 2007 National Forestry
Inventory were used to analyse overlap patterns with ENMs. Niche breadth was greatest
in species from the semiarid Nearctic Region, whereas species richness was associated
with topographic heterogeneity in the Neotropical Region, particularly along the
Pacific Coast. Three species, Triatoma longipennis, Triatoma
mexicana and Triatoma barberi, overlapped with the
greatest numbers of human communities, but these communities had the lowest
rural/urban population ratios. Triatomine vectors have urbanised in most regions,
demonstrating a high tolerance to human-modified habitats and broadened historical
ranges, exposing more than 88% of the Mexican population and leaving few areas in
Mexico without the potential for T. cruzi transmission. 相似文献
13.
Bethany Richards Nicholas M de la Rúa Carlota Monroy Lori Stevens Patricia L Dorn 《Memórias do Instituto Oswaldo Cruz》2013,108(4):395-398
Triatoma dimidiata is the most important Chagas disease insect
vector in Central America as this species is primarily responsible for
Trypanosoma cruzi transmission to humans, the protozoan
parasite that causes Chagas disease. T. dimidiata sensu lato is
a genetically diverse assemblage of taxa and effective vector control requires a
clear understanding of the geographic distribution and epidemiological
importance of its taxa. The nuclear ribosomal internal transcribed spacer 2
(ITS-2) is frequently used to infer the systematics of triatomines. However,
oftentimes amplification and sequencing of ITS-2 fails, likely due to both the
large polymerase chain reaction (PCR) product and polymerase slippage near the
5'' end. To overcome these challenges we have designed new primers that amplify
only the 3''-most 200 base pairs of ITS-2. This region distinguishes the ITS-2
group for 100% of known T. dimidiata haplotypes. Furthermore,
we have developed a PCR-restriction fragment length polymorphism (RFLP) approach
to determine the ITS-2 group, greatly reducing, but not eliminating, the number
of amplified products that need to be sequenced. Although there are limitations
with this new PCR-RFLP approach, its use will help with understanding the
geographic distribution of T. dimidiata taxa and can facilitate
other studies characterising the taxa, e.g. their ecology, evolution and
epidemiological importance, thus improving vector control. 相似文献
14.
Background
Chagas disease is a serious public health problem in Latin America where about ten million individuals show Trypanosoma cruzi infection. Despite significant success in controlling domiciliated triatomines, sylvatic populations frequently infest houses after insecticide treatment which hampers long term control prospects in vast geographical areas where vectorial transmission is endemic. As a key issue, the spatio-temporal dynamics of sylvatic populations is likely influenced by landscape yet evidence showing this effect is rare. The aim of this work is to examine the role of land cover changes in sylvatic triatomine ecology, based on an exhaustive field survey of pathogens, vectors, hosts, and microhabitat characteristics'' dynamics.Methodology and Principal Findings
The study was performed in agricultural landscapes of coastal Ecuador as a study model. Over one year, a spatially-randomized sampling design (490 collection points) allowed quantifying triatomine densities in natural, cultivated and domestic habitats. We also assessed infection of the bugs with trypanosomes, documented their microhabitats and potential hosts, and recorded changes in landscape characteristics. In total we collected 886 individuals, mainly represented by nymphal stages of one triatomine species Rhodnius ecuadoriensis. As main results, we found that 1) sylvatic triatomines had very high T. cruzi infection rates (71%) and 2) densities of T. cruzi-infected sylvatic triatomines varied predictably over time due to changes in land cover and occurrence of associated rodent hosts.Conclusion
We propose a framework for identifying the factors affecting the yearly distribution of sylvatic T. cruzi vectors. Beyond providing key basic information for the control of human habitat colonization by sylvatic vector populations, our framework highlights the importance of both environmental and sociological factors in shaping the spatio-temporal population dynamics of triatomines. A better understanding of the dynamics of such socio-ecological systems is a crucial, yet poorly considered, issue for the long-term control of Chagas disease. 相似文献15.
Aparicio-Burgos JE Ochoa-García L Zepeda-Escobar JA Gupta S Dhiman M Martínez JS de Oca-Jiménez RM Val Arreola M Barbabosa-Pliego A Vázquez-Chagoyán JC Garg NJ 《PLoS neglected tropical diseases》2011,5(5):e1050
Background
Trypanosoma cruzi, the etiologic agent of Chagas Disease, is a major vector borne health problem in Latin America and an emerging infectious disease in the United States.Methods
We tested the efficacy of a multi-component DNA-prime/DNA-boost vaccine (TcVac1) against experimental T. cruzi infection in a canine model. Dogs were immunized with antigen-encoding plasmids and cytokine adjuvants, and two weeks after the last immunization, challenged with T. cruzi trypomastigotes. We measured antibody responses by ELISA and haemagglutination assay, parasitemia and infectivity to triatomines by xenodiagnosis, and performed electrocardiography and histology to assess myocardial damage and tissue pathology.Results
Vaccination with TcVac1 elicited parasite-and antigen-specific IgM and IgG (IgG2>IgG1) responses. Upon challenge infection, TcVac1-vaccinated dogs, as compared to non-vaccinated controls dogs, responded to T. cruzi with a rapid expansion of antibody response, moderately enhanced CD8+ T cell proliferation and IFN-γ production, and suppression of phagocytes’ activity evidenced by decreased myeloperoxidase and nitrite levels. Subsequently, vaccinated dogs controlled the acute parasitemia by day 37 pi (44 dpi in non-vaccinated dogs), and exhibited a moderate decline in infectivity to triatomines. TcVac1-immunized dogs did not control the myocardial parasite burden and electrocardiographic and histopatholgic cardiac alterations that are the hallmarks of acute Chagas disease. During the chronic stage, TcVac1-vaccinated dogs exhibited a moderate decline in cardiac alterations determined by EKG and anatomo-/histo-pathological analysis while chronically-infected/non-vaccinated dogs continued to exhibit severe EKG alterations.Conclusions
Overall, these results demonstrated that TcVac1 provided a partial resistance to T. cruzi infection and Chagas disease, and provide an impetus to improve the vaccination strategy against Chagas disease. 相似文献16.
Carlos H Ni?o Nicolás Forero-Baena Luis E Contreras Diana Sánchez-Lancheros Katherine Figarella María H Ramírez 《Memórias do Instituto Oswaldo Cruz》2015,110(7):890-897
The intracellular parasite Trypanosoma cruzi is the aetiological
agent of Chagas disease, a public health concern with an increasing incidence rate.
This increase is due, among other reasons, to the parasite''s drug resistance
mechanisms, which require nicotinamide adenine dinucleotide (NAD+).
Furthermore, this molecule is involved in metabolic and intracellular signalling
processes necessary for the survival of T. cruzi throughout its life
cycle. NAD+ biosynthesis is performed by de novo and
salvage pathways, which converge on the step that is catalysed by the enzyme
nicotinamide mononucleotide adenylyltransferase (NMNAT) (enzyme commission
number: 2.7.7.1). The identification of the NMNAT of T.
cruzi is important for the development of future therapeutic strategies
to treat Chagas disease. In this study, a hypothetical open reading frame (ORF) for
NMNAT was identified in the genome of T. cruzi. The corresponding
putative protein was analysed by simulating structural models. The ORF was amplified
from genomic DNA by polymerase chain reaction and was further used for the
construction of a corresponding recombinant expression vector. The expressed
recombinant protein was partially purified and its activity was evaluated using
enzymatic assays. These results comprise the first identification of an NMNAT in
T. cruzi using bioinformatics and experimental tools and hence
represent the first step to understanding NAD+ metabolism in these
parasites. 相似文献
17.
José Rodrigues Coura Maurício Humberto Pe?a Marquez Jorge Augusto de Oliveira Guerra Patricia Lago Zauza Julio Cesar Miguel José Borges Pereira 《Memórias do Instituto Oswaldo Cruz》2013,108(7):909-913
The serology of human
Trypanosoma cruzi
infection in the Rio Negro microregion is very complex because of the large numbers of false-positive cases that result from low antibody titres and cross-reactions with other infections. In the present study, we collected 4,880 blood samples on filter paper; of these, indirect immunofluorescence (IIF) was strongly reactive in 221 (4.5%), which were considered to be positive (IIF strongly reactive; high intensity of fluorescence) and weakly reactive in 302 (6.2%), which were considered to be doubtful (IIF weakly reactive; low intensity of fluorescence). The confirmatory test on the serum using at least two of three techniques (IIF, conventional ELISA and recombinant ELISA) on 137 samples that were positive in the screening test only confirmed 33 cases (24.1%). Of the 178 samples that were considered doubtful in the screening test, only 10 (5.6%) were considered to be positive in the confirmatory test. Finally, we recommend that the serological diagnosis of
T. cruzi
infection in the Amazon region be made using at least two different techniques, for example immunofluorescence and ELISA and confirmed by Western blot analysis when possible. 相似文献
18.
Julie Péneau Anne Nguyen Alheli Flores-Ferrer Denis Blanchet Sébastien Gourbière 《PLoS neglected tropical diseases》2016,10(2)
The effects of biodiversity on the transmission of infectious diseases now stand as a cornerstone of many public health policies. The upper Amazonia and Guyana shield are hot-spots of biodiversity that offer genuine opportunities to explore the relationship between the risk of transmission of Chagas disease and the diversity of its triatomine vectors. Over 730 triatomines were light-trapped in four geomorphological landscapes shaping French-Guiana, and we determined their taxonomic status and infection by Trypanosoma cruzi. We used a model selection approach to unravel the spatial and temporal variations in species abundance, diversity and infection. The vector community in French-Guiana is typically made of one key species (Panstrongylus geniculatus) that is more abundant than three secondary species combined (Rhodnius pictipes, Panstrongylus lignarius and Eratyrus mucronatus), and four other species that complete the assemblage. Although the overall abundance of adult triatomines does not vary across French-Guiana, their diversity increases along a coastal-inland gradient. These variations unravelled a non-monotonic relationship between vector biodiversity and the risk of transmission of Chagas disease, so that intermediate biodiversity levels are associated with the lowest risks. We also observed biannual variations in triatomine abundance, representing the first report of a biannual pattern in the risk of Chagas disease transmission. Those variations were highly and negatively correlated with the average monthly rainfall. We discuss the implications of these patterns for the transmission of T. cruzi by assemblages of triatomine species, and for the dual challenge of controlling Amazonian vector communities that are made of both highly diverse and mostly intrusive species. 相似文献
19.
José Rodrigues Coura 《Memórias do Instituto Oswaldo Cruz》2015,110(3):277-282
This review deals with transmission of Trypanosoma cruzi by
the most important domestic vectors, blood transfusion and oral intake. Among the
vectors, Triatoma infestans, Panstrongylus
megistus, Rhodnius prolixus, Triatoma
dimidiata, Triatoma brasiliensis, Triatoma
pseudomaculata, Triatoma sordida, Triatoma
maculata, Panstrongylus geniculatus, Rhodnius
ecuadoriensis and Rhodnius pallescens can be highlighted.
Transmission of Chagas infection, which has been brought under control in some
countries in South and Central America, remains a great challenge, particularly
considering that many endemic countries do not have control over blood donors.
Even more concerning is the case of non-endemic countries that receive thousands
of migrants from endemic areas that carry Chagas disease, such as the United
States of America, in North America, Spain, in Europe, Japan, in Asia, and
Australia, in Oceania. In the Brazilian Amazon Region, since Shaw et al. (1969)
described the first acute cases of the disease caused by oral transmission,
hundreds of acute cases of the disease due to oral transmission have been
described in that region, which is today considered to be endemic for oral
transmission. Several other outbreaks of acute Chagas disease by oral transmission
have been described in different states of Brazil and in other South American
countries. 相似文献
20.
Claudia Nieto-Sanchez Esteban G Baus Darwin Guerrero Mario J Grijalva 《Memórias do Instituto Oswaldo Cruz》2015,110(3):299-309
Chagas disease is caused by Trypanosoma cruzi, which is mainly transmitted by the
faeces of triatomine insects that find favourable environments in poorly constructed
houses. Previous studies have documented persistent triatomine infestation in houses
in the province of Loja in southern Ecuador despite repeated insecticide and
educational interventions. We aim to develop a sustainable strategy for the
interruption of Chagas disease transmission by promoting living environments that are
designed to prevent colonisation of rural houses by triatomines. This study used
positive deviance to inform the design of an anti-triatomine prototype house by
identifying knowledge, attitudes and practices used by families that have remained
triatomine-free (2010-2012). Positive deviants reported practices that included
maintenance of structural elements of the house, fumigation of dwellings and animal
shelters, sweeping with "insect repellent" plants and relocation of domestic animals
away from the house, among others. Participants favoured construction materials that
do not drastically differ from those currently used (adobe walls and tile roofs).
They also expressed their belief in a clear connection between a clean house and
health. The family''s economic dynamics affect space use and must be considered in the
prototype''s design. Overall, the results indicate a positive climate for the
introduction of housing improvements as a protective measure against Chagas disease
in this region. 相似文献