Dataset Information

Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transmission pattern.

ABSTRACT: In South America, fascioliasis stands out due to the human endemic areas in many countries. In Argentina, human endemic areas have recently been detected. Lymnaeid vectors were studied in two human endemic localities of Catamarca province: Locality A beside Taton and Rio Grande villages; Locality B close to Recreo town.Lymnaeids were characterised by the complete sequences of rDNA ITS-2 and ITS-1 and fragments of the mtDNA 16S and cox1. Shell morphometry was studied with the aid of a computer image analysis system. Climate analyses were made by nearest neighbour interpolation from FAO data. Koeppen & Budyko climate classifications were used. De Martonne aridity index and Gorczynski continentality index were obtained. Lymnaeid distribution was assessed in environmental studies.DNA sequences demonstrated the presence of Lymnaea neotropica and L. viator in Locality A and of L. neotropica in Locality B. Two and four new haplotypes were found in L. neotropica and L. viator, respectively. For interspecific differentiation, ITS-1 and 16S showed the highest and lowest resolution, respectively. For intraspecific analyses, cox1 was the best marker and ITS-1 the worst. Shell intraspecific variability overlapped in both species, except maximum length which was greater in L. viator. The desertic-arid conditions surrounding Locality A, the semiaridity-aridity surrounding Locality B, and the very low yearly precipitation in both localities, are very different from the typical fascioliasis transmission foci. Lymnaeids are confined to lateral river side floodings and small man-made irrigation systems. Water availability only depends on the rivers flowing from neighbouring mountains. All disease transmission factors are concentrated in small areas where humans and animals go for water supply, vegetable cultures and livestock farming.The unusually high number of DNA haplotypes and the extreme climate unsuitable for F. hepatica and lymnaeid development, demonstrate that the transmission foci are isolated. Seasonal transmission may depend on the timely overlap of appropriate temperature and river water availability. Lymnaeids and F. hepatica have probably reached these localities by livestock introduction. DNA differences regarding other populations of L. neotropica and L. viator in Argentina suggest an introduction independent from the spreading movements which allowed these two lymnaeids to expand throughout the country.

SUBMITTER: Bargues MD

PROVIDER: S-EPMC4882814 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transmission pattern.

Bargues María Dolores MD Malandrini Jorge Bruno JB Artigas Patricio P Soria Claudia Cecilia CC Velásquez Jorge Néstor JN Carnevale Silvana S Mateo Lucía L Khoubbane Messaoud M Mas-Coma Santiago S

Parasites & vectors 20160527 1

<h4>Background</h4>In South America, fascioliasis stands out due to the human endemic areas in many countries. In Argentina, human endemic areas have recently been detected. Lymnaeid vectors were studied in two human endemic localities of Catamarca province: Locality A beside Taton and Rio Grande villages; Locality B close to Recreo town.<h4>Methods</h4>Lymnaeids were characterised by the complete sequences of rDNA ITS-2 and ITS-1 and fragments of the mtDNA 16S and cox1. Shell morphometry was st ...[more]

PMID: 27229862

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Project description:Fascioliasis is a worldwide emerging snail-borne zoonotic trematodiasis with a great spreading capacity linked to animal and human movements, climate change, and anthropogenic modifications of freshwater environments. South America is the continent with more human endemic areas caused by Fasciola hepatica, mainly in high altitude areas of Andean regions. The Peruvian Cajamarca area presents the highest human prevalences reported, only lower than those in the Bolivian Altiplano. Sequencing of the complete rDNA ITS-2 allowed for the specific and haplotype classification of lymnaeid snails collected in seasonal field surveys along a transect including 2007-3473 m altitudes. The species Galba truncatula (one haplotype preferentially in higher altitudes) and Pseudosuccinea columella (one haplotype in an isolated population), and the non-transmitting species Lymnaea schirazensis (two haplotypes mainly in lower altitudes) were found. Climatic seasonality proved to influence G. truncatula populations in temporarily dried habitats, whereas L. schirazensis appeared to be more climatologically independent due to its extreme amphibious ecology. Along the southeastern transect from Cajamarca city, G. truncatula and L. schirazensis shared the same site in 7 localities (46.7% of the water collections studied). The detection of G. truncatula in 11 new foci (73.3%), predominantly in northern localities closer to the city, demonstrate that the Cajamarca transmission risk area is markedly wider than previously considered. Lymnaea schirazensis progressively increases its presence when moving away from the city. Results highlight the usefulness of lymnaeid surveys to assess borders of the endemic area and inner distribution of transmission foci. Similar lymnaeid surveys are still in need to be performed in the wide northern and western zones of the Cajamarca city. The coexistence of more than one lymnaeid transmitting species, together with a morphologically indistinguishable non-transmitting species and livestock movements inside the area, conform a complex scenario which poses difficulties for the needed One Health control intervention.

Project description: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.

Project description: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.

Project description:BackgroundLivestock 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.ResultsThe 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.ConclusionsITS-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.

Dataset Information

Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transmission pattern.

Publications

Human fascioliasis endemic areas in Argentina: multigene characterisation of the lymnaeid vectors and climatic-environmental assessment of the transmission pattern.

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