RESUMO
The Northern Bolivian Altiplano is the fascioliasis endemic area with the reported highest human prevalence and intensities. A multidisciplinary One Health initiative was implemented to decrease infection/reinfection rates detected by periodic monitoring between the ongoing yearly preventive chemotherapy campaigns. Within a One Health axis, the information obtained throughout 35 years of field work on transmission foci and affected rural schools and communities/villages is analysed. Aspects linked to human infection risk are quantified, including: (1) geographical extent of the endemic area, its dynamics, municipalities affected, and its high strategic importance; (2) human population at risk, community development and mortality rates, with emphasis on problems in infancy and gender; (3) characteristics of the freshwater collections inhabited by lymnaeid snail vectors and constituting transmission foci; (4) food infection sources, including population surveys with questionnaire and reference to the most risky edible plant species; (5) water infection sources; (6) household characteristics; (7) knowledge of the inhabitants on Fasciola hepatica and the disease; (8) behavioural, traditional, social, and religious aspects; (9) livestock management. This is the widest and deepest study of this kind ever performed. Results highlight prevention and control difficulties where inhabitants follow century-old behaviours, traditions, and beliefs. Intervention priorities are proposed and discussed.
Assuntos
Fasciolíase , Saúde Única , Animais , Bolívia/epidemiologia , Fasciolíase/epidemiologia , Fasciolíase/prevenção & controle , Habitação , Humanos , Gado , ÁguaRESUMO
BACKGROUND: Triatomine bugs, the vectors of Chagas disease, associate with vertebrate hosts in highly diverse ecotopes. It has been proposed that occupation of new microhabitats may trigger selection for distinct phenotypic variants in these blood-sucking bugs. Although understanding phenotypic variation is key to the study of adaptive evolution and central to phenotype-based taxonomy, the drivers of phenotypic change and diversity in triatomines remain poorly understood. METHODS/RESULTS: We combined a detailed phenotypic appraisal (including morphology and morphometrics) with mitochondrial cytb and nuclear ITS2 DNA sequence analyses to study Rhodnius ecuadoriensis populations from across the species' range. We found three major, naked-eye phenotypic variants. Southern-Andean bugs primarily from vertebrate-nest microhabitats (Ecuador/Peru) are typical, light-colored, small bugs with short heads/wings. Northern-Andean bugs from wet-forest palms (Ecuador) are dark, large bugs with long heads/wings. Finally, northern-lowland bugs primarily from dry-forest palms (Ecuador) are light-colored and medium-sized. Wing and (size-free) head shapes are similar across Ecuadorian populations, regardless of habitat or phenotype, but distinct in Peruvian bugs. Bayesian phylogenetic and multispecies-coalescent DNA sequence analyses strongly suggest that Ecuadorian and Peruvian populations are two independently evolving lineages, with little within-lineage phylogeographic structuring or differentiation. CONCLUSIONS: We report sharp naked-eye phenotypic divergence of genetically similar Ecuadorian R. ecuadoriensis (nest-dwelling southern-Andean vs palm-dwelling northern bugs; and palm-dwelling Andean vs lowland), and sharp naked-eye phenotypic similarity of typical, yet genetically distinct, southern-Andean bugs primarily from vertebrate-nest (but not palm) microhabitats. This remarkable phenotypic diversity within a single nominal species likely stems from microhabitat adaptations possibly involving predator-driven selection (yielding substrate-matching camouflage coloration) and a shift from palm-crown to vertebrate-nest microhabitats (yielding smaller bodies and shorter and stouter heads). These findings shed new light on the origins of phenotypic diversity in triatomines, warn against excess reliance on phenotype-based triatomine-bug taxonomy, and confirm the Triatominae as an informative model system for the study of phenotypic change under ecological pressure .
Assuntos
Adaptação Fisiológica , Triatominae/genética , Animais , Evolução Biológica , Ecossistema , Equador , Humanos , Insetos Vetores/anatomia & histologia , Insetos Vetores/classificação , Insetos Vetores/genética , Insetos Vetores/fisiologia , Peru , Fenótipo , Filogenia , Seleção Genética , Triatominae/anatomia & histologia , Triatominae/classificação , Triatominae/fisiologiaRESUMO
The Northern Bolivian Altiplano is the human fascioliasis hyperendemic area where the highest prevalences and intensities of infection by Fasciola hepatica in humans have been reported. Four animal species are the reservoir species for F. hepatica in this area, namely, sheep, cattle, pigs, and donkeys. Livestock for the Aymara inhabitants is crucial because vegetable cultures are not viable due to the inhospitality of the very high altitude of 3,820-4,100 m. A One Health initiative has been implemented in this area in recent years, as the first such control action in a human endemic area ever. Among the different control axes included, special focus is devoted to the two main reservoirs sheep and cattle. Egg embryonation, miracidial infectivity, intramolluscan development, cercarial production, infected snail survival, and metacercarial infectivity were experimentally studied in altiplanic sheep and cattle isolates. These laboratory studies were performed using altiplanic isolates of the lymnaeid species Galba truncatula, the only vector present in the hyperendemic area. Experiments were made at constant 12 h day/12 h night and varying 20/20°C and 22/5°C photoperiods. Infections were implemented using mono-, bi-, and trimiracidial doses. Results demonstrate that sheep and cattle have the capacity to assure F. hepatica transmission in this very high-altitude area. Field surveys included prevalence studies by coprology on fecal samples from 1,202 sheep and 2,690 cattle collected from different zones of the Northern Bolivian Altiplano. Prevalences were pronouncedly higher and more homogeneous in sheep (63.1%; range: 38.9-68.5%) than in cattle (20.6%; range: 8.2-43.3%) in each one of the different zones. Although similarities between the prevalences in sheep and cattle appeared in the zones of the highest and lowest infection rates, this disappeared in the other zones due to cattle treatments. Comparison with past surveys demonstrates that this hyperendemic area is stable from the disease transmission point of view. Therefore, the control design should prioritize sheep and cattle within the One Health action. Studies performed in the Bolivian Altiplano furnish a baseline for future initiatives to assess the transmission and epidemiological characteristics of fascioliasis in the way for its control in other high altitude Andean endemic areas.
RESUMO
BACKGROUND: Fascioliasis is a snail-borne zoonotic trematodiasis emerging due to climate changes, anthropogenic environment modifications, and livestock movements. Many areas where Fasciola hepatica is endemic in humans have been described in Latin America altitude areas. Highest prevalences and intensities were reported from four provinces of the northern Bolivian Altiplano, where preventive chemotherapy is ongoing. New strategies are now incorporated to decrease infection/re-infection risk, assessment of human infection sources to enable efficient prevention measures, and additionally a One Health initiative in a selected zone. Subsequent extension of these pilot interventions to the remaining Altiplano is key. METHODS: To verify reproducibility throughout, 133 specimens from 25 lymnaeid populations representative of the whole Altiplano, and 11 used for population dynamics studies, were analyzed by rDNA ITS2 and ITS1 and mtDNA cox1 and 16S sequencing to assess their classification, variability and geographical spread. RESULTS: Lymnaeid populations proved to belong to a monomorphic group, Galba truncatula. Only a single cox1 mutation was found in a local population. Two cox1 haplotypes were new. Comparisons of transmission foci data from the 1990's with those of 2018 demonstrated an endemic area expansion. Altitudinal, northward and southward expansions suggest movements of livestock transporting G. truncatula snails, with increasing temperatures transforming previously unsuitable habitats into suitable transmission areas. Transmission foci appear to be stable when compared to past field observations, except for those modified by human activities, including construction of new roads or control measures undertaken in relation to fascioliasis. CONCLUSIONS: For a One Health initiative, the control of only one Fasciola species and snail vector species simplifies efforts because of the lower transmission complexity. Vector monomorphism suggests uniformity of vector population responses after control measure implementation. Hyperendemic area outer boundary instability suggests a climate change impact. All populations outside previously known boundaries were close to villages, human dwellings and/or schools, and should therefore be considered during disease control planning. The remarkable southward expansion implies that a fifth province, Aroma, should now be included within preventive chemotherapy programmes. This study highlights the need for lymnaeid molecular identification, transmission foci stability monitoring, and potential vector spread assessment.
Assuntos
Vetores de Doenças , Ecossistema , Fasciola hepatica/genética , Fasciolíase/epidemiologia , Lymnaea/parasitologia , Saúde Única , Animais , DNA Mitocondrial/genética , DNA Espaçador Ribossômico/genética , Doenças Endêmicas , Fasciolíase/parasitologia , Geografia , Haplótipos , Humanos , Filogenia , PrevalênciaRESUMO
PURPOSE: Fascioliasis is a freshwater snail-borne zoonotic trematodiasis of high pathogenicity and wide veterinary repercussions. In South America, moreover, it causes serious public health problems, with high human infection rates in Andean countries. Ecuador offers a worrying risky scenario due to its physiography, including many human infection reports and animal endemicity throughout its Andean highlands. METHODS: Endemic areas with increasing animal fascioliasis were surveyed for lymnaeid snails in the province of Loja, southern Ecuador, close to the border of Peru, the country known to present the widest human fascioliasis endemic zone. The altitude of the sampling sites ranged between 150 and 1770 m a.s.l., and their location was close to human villages. Biotopes surveyed were characterized according to fascioliasis transmission needs. RESULTS: The species Lymnaea schirazensis and L. neotropica were identified by rDNA ITS-2 and ITS-1 sequencing. The non-transmitting L. schirazensis combined haplotype agreed with populations of this species previously reported from northern Ecuador. The finding of the efficient vector L. neotropica is reported for the first time in Ecuador and suggests a passive introduction from neighbouring Peru by uncontrolled livestock transport. CONCLUSIONS: Rice irrigation system implementation, lymnaeid finding on Taraxacum (dandelion) plants which are consumed fresh in salads by people, and Saccharum (sugarcane), whose bark is peeled off with the teeth, represent potential infection sources for humans. The closeness to the Cajamarca human hyperendemic area in northern Peru, where the same two lymnaeids have been also found and triclabendazole resistance reported, is an additional risk to be considered regarding the livestock transborder exchange.
Assuntos
Vetores de Doenças , Doenças Endêmicas/veterinária , Fasciolíase/veterinária , Lymnaea/classificação , Lymnaea/parasitologia , Análise de Sequência de DNA , Animais , DNA Espaçador Ribossômico/genética , Equador , Fasciolíase/transmissão , Geografia , Haplótipos , PeruRESUMO
Fascioliasis is a plantborne and zoonotic parasitic disease caused by fasciolid liver flukes. Fasciola hepatica is the only fasciolid species described in the Americas. Human fascioliasis endemic areas are mainly located in high altitude areas of the Americas. Given the necessity to characterize F. hepatica populations involved, the phenotypic and genotypic features of fasciolid adults infecting cattle in the highland area of Toluca, State of Mexico, Mexico, were analyzed and compared to fasciolid materials from the Northern Bolivian Altiplano, representing the altiplanic transmission pattern in a hyperendemic scenario. A computer image analysis system (CIAS) was applied on the basis of standardized measurements. The aforementioned F. hepatica highland populations were compared to standard lowland natural populations of European origin (Spain and France) and F. gigantica of African origin (Burkina Faso). Liver-fluke size was studied by principal component analysis (PCA). Two phenotypic patterns could be distinguished in the F. hepatica material analyzed from the Americas: the valley pattern (Toluca, Mexico) and the altiplanic pattern (Northern Altiplano, Bolivia). PCA showed that the Altiplano population presented a large body size range with a pronouncedly lower minimum size. Mahalanobis distances demonstrated that American populations are very close to European populations. Genetic haplotyping was performed using the ribosomal DNA intergenic region, including ITS-1, 5.8S and ITS-2. The intergenic region was 951â¯bp-long, providing 2 combined haplotypes due to one mutation appearing in the ITS-2 sequence. Molecular results showed that Fh-1A and Fh-2A, the most frequent haplotypes of F. hepatica from southern Europe, are present in Mexican cattle. Nuclear rDNA biomarkers correlated with adult fluke phenotypic characteristics. Results showed that the Mexican population analyzed and European standard populations presented a phenotypic and genotypic homogeneity, suggesting an introduction with livestock transported during the early colonization period. Results are moreover analyzed in terms of altitude and permanent/seasonal transmission characteristics.
Assuntos
Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Fasciola hepatica/classificação , Fasciola hepatica/genética , Fasciolíase/veterinária , Genótipo , Fenótipo , Animais , Composição de Bases , Bovinos , DNA Ribossômico , Fasciola hepatica/anatomia & histologia , Geografia Médica , Haplótipos , México/epidemiologia , Análise de SequênciaRESUMO
BACKGROUND: Triatoma infestans is the main vector of Chagas disease in South America. As in all hematophagous arthropods, its saliva contains a complex cocktail that assists blood feeding by preventing platelet aggregation and blood clotting and promoting vasodilation. These salivary components can be immunologically recognized by their vector's hosts and targeted with antibodies that might disrupt blood feeding. These antibodies can be used to detect vector exposure using immunoassays. Antibodies may also contribute to the fast evolution of the salivary cocktail. METHODOLOGY: Salivary gland cDNA libraries from nymphal and adult T. infestans of breeding colonies originating from different locations (Argentina, Chile, Peru and Bolivia), and cDNA libraries originating from F1 populations of Bolivia, were sequenced using Illumina technology. Coding sequences (CDS) were extracted from the assembled reads, the numbers of reads mapped to these CDS, sequences were functionally annotated and polymorphisms determined. MAIN FINDINGS/SIGNIFICANCE: Over five thousand CDS, mostly full length or near full length, were publicly deposited on GenBank. Transcripts that were over 10-fold overexpressed from different geographical regions, or from different developmental stages were identified. Polymorphisms were mapped to derived coding sequences, and found to vary between developmental instars and geographic origin of the biological material. This expanded sialome database from T. infestans should be of assistance in future proteomic work attempting to identify salivary proteins that might be used as epidemiological markers of vector exposure, or proteins of pharmacological interest.
Assuntos
Biblioteca Gênica , Saliva/química , Proteínas e Peptídeos Salivares/genética , Transcriptoma/genética , Triatoma/genética , Animais , Proteínas e Peptídeos Salivares/metabolismo , América do Sul , Triatoma/metabolismoRESUMO
BACKGROUND: Human and animal fascioliasis is emerging in many world regions, among which Andean countries constitute the largest regional hot spot and Peru the country presenting more human endemic areas. A survey was undertaken on the lymnaeid snails inhabiting the hyperendemic area of Cajamarca, where human prevalences are the highest known among the areas presenting a "valley transmission pattern", to establish which species are present, genetically characterise their populations by comparison with other human endemic areas, and discuss which ones have transmission capacity and their potential implications with human and animal infection. METHODS: Therefore, ribosomal DNA ITS-2 and ITS-1, and mitochondrial DNA 16S and cox1 were sequenced by the dideoxy chain-termination method. RESULTS: Results indicate the presence of three, morphologically similar, small lymnaeid species belonging to the Galba/Fossaria group: Galba truncatula, Lymnaea neotropica and L. schirazensis. Only one combined haplotype for each species was found. The ITS-1, 16S and cox1 haplotypes of G. truncatula are new. No new haplotypes were found in the other two species. This scenario changes previous knowledge, in which only L. viator (= L. viatrix) was mentioned. Galba truncatula appears to be the most abundant, with high population densities and evident anthropophyly including usual presence in human neighbourhood. Infection by Fasciola hepatica larval stages were molecularly confirmed in two populations of this species. The nearness between G. truncatula populations presenting liver fluke infection and both human settings and schools for children, together with the absence of populations of other lymnaeid species in the locality, suggest a direct relationship with human infection. CONCLUSIONS: The geographical overlap of three lymnaeid species poses problems for epidemiological studies and control action. First, a problem in classifying lymnaeid specimens in both field and laboratory activities, given their transmission capacity differences: G. truncatula mainly involved in transmission to humans, L neotropica typically responsible for livestock infection, and L. schirazensis unable for transmission. Although several phenotypic characteristics may be helpful for a preliminary specimen classification, a definitive classification can only be obtained by marker sequencing. Aditionally, L. schirazensis increases the confusion, owing to its ability to mix with other Galba/Fossaria species and distort fascioliasis data such as transmission capacity and infection susceptibility. Second, a problem for epidemiological analysis, surveillance and control by methods as mathematical modelling and Remote Sensing--Geographical Information Systems. In Cajamarca, low resolution mapping may be insufficient, as already verified in Andean areas where different lymnaeid species overlap.
Assuntos
Fasciola/fisiologia , Fasciolíase/transmissão , Caramujos/genética , Caramujos/parasitologia , Animais , Sequência de Bases , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 1/metabolismo , DNA Mitocondrial/genética , Reservatórios de Doenças , Fasciolíase/epidemiologia , Fasciolíase/parasitologia , Interações Hospedeiro-Parasita , Humanos , Larva/fisiologia , Peru/epidemiologia , Reação em Cadeia da Polimerase/métodos , Densidade Demográfica , RNA Ribossômico 16S/genéticaRESUMO
BACKGROUND: Human and animal fascioliasis poses serious public health problems in South America. In Venezuela, livestock infection represents an important veterinary problem whereas there appear to be few human cases reported, most of which are passively detected in health centres. However, results of recent surveys suggest that the situation may be underestimated in particular areas. To obtain a baseline for future fascioliasis assessment, studies were undertaken by means of rDNA ITS-2 and ITS-1 and mtDNA cox1 sequencing to clarify the specific status of Venezuelan lymnaeids, their geographical distribution and fascioliasis transmission capacity, by comparison with other American countries and other continents. RESULTS: Results obtained completely change the lymnaeid scenario known so far. The relatively rich lymnaeid fauna of Venezuela has been proven to include (i) Lymnaea meridensis and L. neotropica as the only native members, (ii) L. cubensis and Pseudosuccinea columella introduced from the Caribbean area, and (iii) Galba truncatula and L. schirazensis introduced from the Old World. The absence of representatives of the stagnicoline and Radix groups is remarkable. Four species are fascioliasis vectors: G. truncatula, L. cubensis and L. neotropica, which have the capacity to give rise to human endemic areas, and P. columella, which is a source of animal infection and is responsible for the spread of disease. Vector capacity in the apparently highland endemic L. meridensis is to be confimed, although may be expected given its phylogenetic relationships. Similarly as elsewhere, the non-transmitting L. schirazensis has been confused with L. cubensis, also with G. truncatula and possibly with L. neotropica. CONCLUSIONS: The new scenario leads to the re-opening of many disease aspects. In Venezuela, altitude appears to be the main factor influencing fascioliasis distribution. Human infection shows an altitude pattern similar to other Andean countries, although a differing highland/lowland impact on animal infection does not appear evident. The overlap of G. truncatula, L. cubensis and probably also L. neotropica in temperate and cold zones suggests a higher risk for human infection in mid and high altitude areas. A lymnaeid species mapping by means of DNA markers becomes a priority to determine human and animal fascioliasis distribution in Venezuela, owing to the importance of lymnaeid vectors in defining transmission and epidemiological patterns.
Assuntos
Vetores de Doenças/classificação , Fasciolíase/transmissão , Fasciolíase/veterinária , Caramujos/classificação , Caramujos/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Fasciola hepatica/isolamento & purificação , Fasciola hepatica/fisiologia , Fasciolíase/parasitologia , Humanos , Gado/parasitologia , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNA , Caramujos/parasitologia , VenezuelaRESUMO
In South America, Fasciola hepatica infection poses serious health problems in both humans and livestock. In Chile, the medical impact appears yearly stable and mainly concentrated in central regions, where the veterinary problem is highlighted by higher animal prevalences. Studies were undertaken by rDNA ITS-2 and ITS-1 and mtDNA cox1 sequencing to clarify the specific status of the lymnaeids, their geographical distribution and fascioliasis transmission capacity in Chile, by comparison with other American countries and continents. Results change the lymnaeid scenario known so far. The lymnaeid fauna of mainland Chile shows to be poor, including only two authochthonous species, Lymnaea viator and Pectinidens diaphana, and a third introduced species of Palaearctic origin Galba truncatula. Both Lymnaea lebruni and Lymnaea patagonica proved to be synonyms of P. diaphana. G. truncatula appears to have always been confused with L. viator and seems distributed from Región VI to Región IX, overlapping with human endemic areas. DNA sequencing results suggest that the absence of correlation between remote sensing data and disease prevalences could be due to transmission capacity differences between L. viator and G. truncatula. Results furnish a new baseline on which to undertake future appropriate studies on transmission, epidemiology and control.
Assuntos
Acanthaceae/parasitologia , Fasciola hepatica/classificação , Fasciola hepatica/isolamento & purificação , Animais , Chile , Análise por Conglomerados , DNA de Helmintos/química , DNA de Helmintos/genética , DNA Mitocondrial/química , DNA Mitocondrial/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Fasciola hepatica/genética , Proteínas Mitocondriais/genética , Dados de Sequência Molecular , Filogenia , Análise de Sequência de DNARESUMO
A coprological survey including 476 2-18 year old school children from six rural localities between 2627 and 3061 m altitude was performed in Cajamarca province, Peru. Prevalences of fascioliasis ranging from 6.7 to 47.7% (mean 24.4%) proved to be the highest so far recorded in that human hyperendemic area. Higher prevalences in females and in the 2-5 year old group were not significant. Intensities ranged from 24 to 864 eggs per gram (arithmetic mean: 113; geometric mean: 68), the majority shedding less than 100, and without significant differences according to gender or age group. Fasciola hepatica was the most common helminth within a spectrum of 11-12 protozoan and 9-11 helminth species, 97.3% of the children showing infection with at least one parasite. The highest levels corresponded to coinfection with seven different species in females and subjects older than 5 years. Fascioliasis prevalence correlation with altitude appeared significant. An epidemiological characterisation of the valley transmission pattern of fascioliasis in Cajamarca is made by comparison with other better known hyperendemic areas. Results suggest that human fascioliasis may be widespread throughout different parts of Cajamarca province, even far away from the city, and that long-term fascioliasis chronicity and superimposed repetitive infections may be probably frequent.
Assuntos
Altitude , Fasciola hepatica/isolamento & purificação , Fasciolíase/epidemiologia , Fezes/parasitologia , Distribuições Estatísticas , Adolescente , Animais , Criança , Pré-Escolar , Coinfecção/parasitologia , Meio Ambiente , Feminino , Humanos , Masculino , Contagem de Ovos de Parasitas , Peru/epidemiologia , PrevalênciaRESUMO
BACKGROUND: Livestock fascioliasis is a problem throughout Ecuador, Colombia and Venezuela, mainly in Andean areas where the disease also appears to affect humans. Transmission patterns and epidemiological scenarios of liver fluke infection have shown to differ according to the lymnaeid vector snail species involved. These Andean countries present the vectors Lymnaea cousini, L. bogotensis and L. ubaquensis, unknown in the rest of Latin America. An exhaustive combined haplotype study of these species is performed by means of DNA sequencing of the nuclear ribosomal 18S RNA gene, ITS-2 and ITS-1, and mitochondrial DNA cox1 gene. RESULTS: The conserved 5.8S rDNA sequence corroborated that no pseudogenes are involved in the numerous non-microsatellite/minisatellite-related indels appearing between the ITS-2 and ITS-1 sequences when comparing different L. cousini--L. bogotensis populations. Sequence analyses and phylogenetic reconstruction methods including other lymnaeid vector species show that (i) L. bogotensis is a synonym of L. cousini, (ii) L. ubaquensis is a synonym of Pseudosuccinea columella, and (iii) populations of L. cousini hitherto known from Venezuelan highlands indeed belong to a new species for which the name L. meridensis n. sp. is proposed. This new species is described and a complete phenotypic differentiation provided. CONCLUSIONS: ITS-2, ITS-1 and cox1 prove to be good markers for specimen classification and haplotype characterisation of these morphologically similar lymnaeids in endemic areas. Analysis of the 18S gene and phylogenetic reconstructions indicate that L. cousini and L. meridensis n. sp. cluster in an evolutionary line different from the one of P. columella, despite their external resemblance. This suggests an evolutionary phenotypic convergence related to similar environments and which has given rise to frequent specimen misclassification. Body size and phylogenetic relationships of L. meridensis n. sp. with well-known vectors as Lymnaea cousini and P. columella, as well as with Galba/Fossaria species, suggest that the new species may participate in disease transmission to both animals and humans in altitude areas during the yearly window in which temperatures are higher than the F. hepatica minimum development threshold. The involvement of L. cousini and P. columella in the transmission and geographical/altitudinal distribution of fascioliasis in these Andean countries is analysed.
Assuntos
Vetores de Doenças , Lymnaea/classificação , Lymnaea/genética , Filogeografia , Animais , Análise por Conglomerados , Colômbia , Ciclo-Oxigenase 1/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Equador , Fasciolíase/transmissão , Fasciolíase/veterinária , Dados de Sequência Molecular , RNA Ribossômico 18S/genética , RNA Ribossômico 5,8S/genética , Análise de Sequência de DNA , VenezuelaRESUMO
Phylogenetic studies of Trypanosoma cruzi have identified the existence of two groups: T. cruzi I and T. cruzi II. There are aspects that still remain unknown about the genetic variability within the T. cruzi I group. Given its epidemiological importance, it is necessary to have a better understanding of T. cruzi transmission cycles. Our purpose was to corroborate the existence of haplotypes within the T. cruzi I group and to describe the genetic variability and phylogenetic relationships, based on single nucleotide polymorphisms (SNPs) found in the miniexon gene intergenic region, for the isolates from different hosts and epidemiological transmission cycles in Colombian regions. 31 T. cruzi isolates were molecularly characterized. Phylogenetic relationships within T. cruzi I isolates showed four haplotype groups (Ia-Id), associated with their transmission cycle. In previous studies, we reported that haplotype Ia is mainly associated with the domestic cycle and domiciliated Rhodnius prolixus. Haplotype Ib is associated with the domestic cycle and peridomestic cycle, haplotype Ic is closely related with the peridomestic cycle, and haplotype Id is strongly associated with the sylvatic cycle. The phylogenetic methodologies applied in this study are tools that bolster the associations among isolates and thus shed light on Chagas disease epidemiology.
RESUMO
The performance of Fas2-ELISA for the diagnosis of Fasciola hepatica infection in children living in areas of high endemicity for fascioliasis in the Peruvian Andes is analyzed. Fas2-ELISA is based on the detection of circulating IgG antibodies elicited in infected individuals against a F. hepatica antigen termed Fas2. The study was conducted in three Andean localities, Huertas-Julcan in Junin, Asillo in Puno, and Cajamarca, with a total population of 634 children in an age range 1 to 16 years old. Child fascioliasis prevalence was 21.1% in Huertas-Julcan, 25.4% in Asillo, and 24% in Cajamarca, estimated by coprological inspection. The seroprevalence of F. hepatica infection, determined by Fas2-ELISA, was 27.8% in Huertas-Julcan, 44.6% in Asillo, and 29.1% in Cajamarca. The overall sensitivity of Fas2-ELISA was 92.4%, the specificity 83.6%, and the negative predictive value 97.2%. No association between OD(450) Fas2-ELISA and infection intensity measured by egg counting was observed. Results show that Fas2-ELISA is a highly sensitive immunodiagnostic test for the detection of F. hepatica infection in children living in human fascioliasis endemic areas.
Assuntos
Anticorpos Anti-Helmínticos/sangue , Antígenos de Helmintos/imunologia , Cisteína Endopeptidases/imunologia , Ensaio de Imunoadsorção Enzimática/métodos , Fasciola hepatica/imunologia , Fasciolíase/diagnóstico , Adolescente , Fatores Etários , Animais , Criança , Pré-Escolar , Ensaio de Imunoadsorção Enzimática/normas , Fasciolíase/epidemiologia , Fezes/parasitologia , Feminino , Helmintíase/epidemiologia , Humanos , Imunoglobulina G/sangue , Lactente , Intestinos/parasitologia , Masculino , Peru/epidemiologia , Prevalência , Infecções por Protozoários/epidemiologia , Fatores de Risco , Sensibilidade e EspecificidadeRESUMO
Trypanosoma cruzi has been classified into the groups T. cruzi I and T. cruzi II. The latter is subdivided into five smaller lineages based on multilocus enzyme electrophoresis and random amplified polymorphic DNA, designated as IIa-IIe, which shows correspondence with rRNA/mini-exon lineages. Twelve previously characterised T. cruzi isolates from different hosts, including humans, Didelphis marsupialis, and triatomines were analysed to establish genetic variability in T. cruzi group T. cruzi I isolates from different geographical regions of Colombia. DNA samples were sequenced based on the mini-exon gene intergenic region. Sequences were analysed using Clustal W, Staden 1.5 and MEGA3 software, and using reported sequences from the GenBank as reference. The genetic distances were analysed using Kimura's two-parameter model. The isolates' joint alignment was of 350bp, and the calculated nucleotide divergence was of 17.5%. The differences consisted of 23 transitions (7.2%), 14 transversions (4.4%) and 19 insertion-deletions (5.9%). The Colombian T cruzi I isolates revealed sufficient genetic variability for us to propose the existence of four haplotypes identified through single nucleotide polymorphism (SNP) and insertion/deletion found in the mini-exon gene's non-transcribed spacer intergenic region.
Assuntos
Haplótipos/genética , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificação , Animais , Sequência de Bases , Colômbia , Éxons/genética , Geografia , Repetições de Microssatélites/genética , Dados de Sequência Molecular , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
We detected 10 protozoan and nine helminth species in surveys of 338 5-15 year-old Quechua schoolchildren in three communities of the Asillo zone of the Puno region, located at a very high altitude of 3910 m in the Peruvian Altiplano. The area proved to be hyperendemic for human fascioliasis with a 24.3% overall mean prevalence of Fasciola hepatica, local prevalences ranging between 18.8 and 31.3%, and infection intensities of up to 2496 eggs per gram of faeces (epg), with 196-350 epg (mean: 279 epg) and 96-152 epg (123 epg) as arithmetic and geometric means, respectively. Prevalences did not significantly vary between schools and in relation to sex. No statistical differences were found in intensities between schools, nor according to sex or age groups between and within schools, although the highest overall egg counts were detected in girls and in the youngest age group. Asillo zone is a man-made irrigation area built only recently to which both liver fluke and lymnaeid snails have quickly adapted. The region appears to be isolated from the Northern Bolivian Altiplano natural endemic area. Such man-made water resources in high altitude areas of Andean countries pose a high fascioliasis risk. Significant positive association of F. hepatica with protozooses following a one host life cycle, such as Giardia intestinalis, suggests that human infection mainly occurs through drinking water. This is supported by additional evidence such as the absence of typical aquatic vegetation in the drainage channels inhabited by lymnaeid snails, the absence of aquatic vegetables in the traditional nutrition habits of the Quechua inhabitants, and the lack of potable water systems inside dwellings, which requires inhabitants to obtain water from irrigation canals and drainage channels.