The Last Fifteen Years of Schistosomiasis in Venezuela: Features and Evolution

Noya, Belkisyolé Alarcón de; Balzan, C.; Arteaga, César; Cesari, Italo M.; Noya, Óscar

doi:10.1590/s0074-02761999000200002

Cited by 22 publications

(9 citation statements)

References 11 publications

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“…The Valencia lake basin (Fig. 1) is located in north‐central Venezuela and constitutes the centre of the historical endemic area for schistosomiasis in Venezuela (Alarcón de Noya et al . 1999).…”

Section: Methodsmentioning

confidence: 99%

Fine‐scale population structure and dispersal inBiomphalaria glabrata, the intermediate snail host ofSchistosoma mansoni, in Venezuela

Mavárez

Amarista²,

Pointier

et al. 2002

Molecular Ecology

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Biomphalaria glabrata is the main intermediate host of Schistosoma mansoni in America and one of the most intensely studied species of freshwater snails, yet very little is known about its population biology. Here, we used seven highly polymorphic microsatellite loci to analyse genetic diversity in the Valencia lake basin, which represents the core of the endemic area for schistosomiasis in Venezuela. Populations were sampled at short spatial scale (a few kilometres), both inside the lake and in ponds or rivers near the lake. Our results indicate that B. glabrata essentially cross-fertilizes, with little variation in selfing rates among populations. Our markers detected considerable genetic variation, with an average heterozygosity of 0.60. More diversity per population was found within than outside the lake, suggesting an influence of connectivity among populations on the levels of genetic diversity. A marked population structure was detected and lake populations were less structured than other populations. Most individuals were assigned to their population of origin using an assignment test. No strong demographic signal (e.g. bottleneck) was detected, though lake populations are likely to experience bottlenecks more frequently than the other populations analysed. Differences in gene flow therefore seem to play an important role in population differentiation and in the restoring of genetic diversity in demographically unstable populations.

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Section: Methodsmentioning

confidence: 99%

Fine‐scale population structure and dispersal inBiomphalaria glabrata, the intermediate snail host ofSchistosoma mansoni, in Venezuela

Mavárez

Amarista²,

Pointier

et al. 2002

Molecular Ecology

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“…Concepts for schistosomiasis surveillance systems designed for elimination programs, including early warning systems [ 25 , 58 , 82 – 85 ], mapping of hot spots and modelling for targeted approaches [ 58 , 83 , 86 ] are covered in several reviewed articles. Challenges due to the lack of sensitive diagnostic tools for monitoring and validating stages of elimination in regards to low-prevalence settings and low intensity infections were discussed in articles pertaining to schistosomiasis control programs in Morocco [ 87 ], Venezuela [ 21 , 23 ], Oman [ 20 ] and P.R. China [ 28 ].…”

Section: Resultsmentioning

confidence: 99%

“…Most of the identified articles that focus on strategies for implementation of interventions refer to the Chinese schistosomiasis control programme. They describe a combination of tools and comprehensive strategies [ 11 , 20 , 21 , 23 , 36 , 90 , 92 – 94 ] implemented through collaborations between multiple sectors but under central coordination [ 26 , 29 , 39 , 95 , 96 ]. This approach has been identified as important to reduce schistosomiasis japonica levels across P.R.…”

Section: Resultsmentioning

confidence: 99%

Core components, concepts and strategies for parasitic and vector-borne disease elimination with a focus on schistosomiasis: A landscape analysis

et al. 2020

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Efforts to control and eliminate human schistosomiasis have accelerated over the past decade. In a number of endemic countries and settings, interruption of schistosome transmission has been achieved. In others, Schistosoma infections continue to challenge program managers at different levels, from the complexity of the transmission cycle, over limited treatment options and lack of field-friendly accurate diagnostics, to controversy around adequate intervention strategies. We conducted a landscape analysis on parasitic and vector-borne disease elimination approaches with the aim to identify evidence-based strategies, core components and key concepts for achieving and sustaining schistosomiasis control and for progressing elimination efforts towards interruption of transmission in sub-Saharan Africa. A total of 118 relevant publications were identified from Web of Science, Pubmed and the grey literature and reviewed for their content. In addition, we conducted in-depth interviews with 23 epidemiologists, program managers, policymakers, donors and field researchers. Available evidence emphasizes the need for comprehensive, multipronged and long-term strategies consisting of multiple complementary interventions that must be sustained over time by political commitment and adequate funding in order to reach interruption of transmission. Based on the findings of this landscape analysis, we propose a comprehensive set of intervention strategies for schistosomiasis control and elimination. Before deployment, the proposed interventions will require review, evaluation and validation in the frame of an expert consultation as a step towards adaptation to specific contexts, conditions and settings. Field testing to ensure local relevance and effectiveness is paramount given the diversity of socio-ecological and epidemiological contexts.

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“…Praziquantel (PZQ) remains the main anti-schistosome drug for treatment [3]; however, mass drug administration on Schistosoma mansoni -infected populations do not prevent re-infection and patent infections maintain the foci of transmission in low transmission areas [4]. In addition, the repeated use of chemotherapy can result in other complications such as occurrence of drug resistance.…”

Section: Introductionmentioning

confidence: 99%

Immunoprotection of Mice against Schistosomiasis Mansoni Using Solubilized Membrane Antigens

et al. 2013

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BackgroundSchistosomiasis continues to be one of the most prevalent parasitic diseases in the world. Despite the existence of a highly effective antischistosome drug, the disease is spreading into new areas, and national control programs do not arrive to complete their tasks particularly in low endemic areas. The availability of a vaccine could represent an additional component to chemotherapy. Experimental vaccination studies are however necessary to identify parasite molecules that would serve as vaccine candidates. In the present work, C57BL/6 female mice were subcutaneously immunized with an n-butanol extract of the adult worm particulate membranous fraction (AWBE) and its protective effect against a S. mansoni challenge infection was evaluated.Methodology and FindingsWater-saturated n-butanol release into the aqueous phase a set of membrane-associated (glyco)proteins that are variably recognized by antibodies in schistosome-infected patients; among the previously identified AWBE antigens there is Alkaline Phosphatase (SmAP) which has been associated with resistance to the infection in mice. As compared to control, a significantly lower number of perfuse parasites was obtained in the immunized/challenged mouse group (P<0.05, t test); and consequently, a lower number of eggs and granulomas (with reduced sizes), overall decreasing pathology. Immunized mice produced high levels of sera anti-AWBE IgG recognizing antigens of ∼190-, 130-, 98-, 47-, 28-23, 14-, and 9-kDa. The ∼130-kDa band (the AP dimer) exhibited in situ SmAP activity after addition of AP substrate and the activity was not apparently inhibited by host antibodies. A preliminary proteomic analysis of the 25-, 27-, and 28-kDa bands in the immunodominant 28–23 kDa region suggested that they are composed of actin.ConclusionsImmunization with AWBE induced the production of specific antibodies to various adult worm membrane molecules (including AP) and a partial (43%) protection against a challenging S. mansoni infection by mechanism(s) that still has to be elucidated.

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The Last Fifteen Years of Schistosomiasis in Venezuela: Features and Evolution

Abstract: Control of schistosomiasis in Venezuela has been a topic of major interest and controversy

Cited by 22 publications

References 11 publications

Fine‐scale population structure and dispersal inBiomphalaria glabrata, the intermediate snail host ofSchistosoma mansoni, in Venezuela

Fine‐scale population structure and dispersal inBiomphalaria glabrata, the intermediate snail host ofSchistosoma mansoni, in Venezuela

Core components, concepts and strategies for parasitic and vector-borne disease elimination with a focus on schistosomiasis: A landscape analysis

Immunoprotection of Mice against Schistosomiasis Mansoni Using Solubilized Membrane Antigens

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