Showing papers on "Bulinus truncatus published in 2020"

Interactions between Schistosoma haematobium group species and their Bulinus spp. intermediate hosts along the Niger River Valley.

Abstract: Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is endemic in Niger but complicated by the presence of Schistosoma bovis, Schistosoma curassoni and S. haematobium group hybrids along with various Bulinus snail intermediate host species. Establishing the schistosomes and snails involved in transmission aids disease surveillance whilst providing insights into snail-schistosome interactions/compatibilities and biology. Infected Bulinus spp. were collected from 16 villages north and south of the Niamey region, Niger, between 2011 and 2015. From each Bulinus spp., 20–52 cercariae shed were analysed using microsatellite markers and a subset identified using the mitochondrial (mt) cox1 and nuclear ITS1 + 2 and 18S DNA regions. Infected Bulinus spp. were identified using both morphological and molecular analysis (partial mt cox1 region). A total of 87 infected Bulinus from 24 sites were found, 29 were molecularly confirmed as B. truncatus, three as B. forskalii and four as B. globosus. The remaining samples were morphologically identified as B. truncatus (n = 49) and B. forskalii (n = 2). The microsatellite analysis of 1124 cercariae revealed 186 cercarial multilocus genotypes (MLGs). Identical cercarial genotypes were frequently (60%) identified from the same snail (clonal populations from a single miracidia); however, several (40%) of the snails had cercariae of different genotypes (2–10 MLG’s) indicating multiple miracidial infections. Fifty-seven of the B. truncatus and all of the B. forskalii and B. globosus were shedding the Bovid schistosome S. bovis. The other B. truncatus were shedding the human schistosomes, S. haematobium (n = 6) and the S. haematobium group hybrids (n = 13). Two B. truncatus had co-infections with S. haematobium and S. haematobium group hybrids whilst no co-infections with S. bovis were observed. This study has advanced our understanding of human and bovid schistosomiasis transmission in the Niger River Valley region. Human Schistosoma species/forms (S. haematobium and S. haematobium hybrids) were found transmitted only in five villages whereas those causing veterinary schistosomiasis (S. bovis), were found in most villages. Bulinus truncatus was most abundant, transmitting all Schistosoma species, while the less abundant B. forskalii and B. globosus, only transmitted S. bovis. Our data suggest that species-specific biological traits may exist in relation to co-infections, snail-schistosome compatibility and intramolluscan schistosome development.

Environmental DNA for detecting Bulinus truncatus: A new environmental surveillance tool for schistosomiasis emergence risk assessment

Abstract: HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Environmental DNA for detecting Bulinus truncatus: a new environmental surveillance tool for schistosomiasis emergence risk assessment Stephen Mulero, Jérôme Boissier, Jean-François Allienne, Yann Quilichini, Joséphine Foata, Jean-Pierre Pointier, Rey Olivier

Molecular diversity of Bulinus species in Madziwa area, Shamva district in Zimbabwe: implications for urogenital schistosomiasis transmission

Abstract: Bulinus species are freshwater snails that transmit the parasitic trematode Schistosoma haematobium. Despite their importance, the diversity of these intermediate host snails and their evolutionary history is still unclear in Zimbabwe. Bulinus globosus and B. truncatus collected from a urogenital schistosomiasis endemic region in the Madziwa area of Zimbabwe were characterized using molecular methods. Malacological survey sites were mapped and snails were collected from water contact sites in four communities in the Madziwa area, Shamva district for a period of one year, at three-month intervals. Schistosoma haematobium infections in snails were determined by cercarial shedding and the partial mitochondrial cytochrome c oxidase subunit 1 gene (cox1) was used to investigate the phylogeny and genetic variability of the Bulinus spp. collected. Among the 1570 Bulinus spp. snails collected, 30 (1.9%) B. globosus were shedding morphologically identified schistosomes. None of the B. truncatus snails were shedding. The mitochondrial cox1 data from 166 and 16 samples for B. globosus and B. truncatus, respectively, showed genetically diverse populations within the two species. Twelve cox1 haplotypes were found from the 166 B. globosus samples and three from the 16 B. truncatus samples with phylogenetic analysis showing that the haplotypes fall into well-supported clusters within their species groups. Both B. truncatus and B. globosus clustered into two distinct lineages. Overall, significant negative values for both Tajima’s D statistic and the Fu’s Fs statistic were observed for B. globosus and B. truncatus. The study provided new insights into the levels of genetic diversity within B. globosus and additional information on B. truncatus collected from a small geographical area in Zimbabwe. Low prevalence levels of infection observed in the snails may reflect the low transmission level of urogenital schistosomiasis in the area. Our results contribute towards the understanding of the distribution and population genetic structure of Bulinus spp. supporting the mapping of the transmission or risk of transmission of urogenital schistosomiasis, particularly in Zimbabwe.

Semi-field and field trials to control Biomphalaria alexandrina and Bulinus truncatus, intermediate host snails of schistosomiasis in Egypt by the plant molluscicide Luowei/TDS 4%

Abstract: Controlling the snail intermediate hosts of schistosomiasis is an efficient and rapid method for reducing or eliminating the transmission of this disease. The present study aimed to assess the molluscicidal activity of Luowei/TDS 4% against Biomphalaria alexandrina and Bulinus truncatus under semi-field and field conditions in Egypt. Moreover, its effect on Schistosoma mansoni miracidial viability and infectivity to B. alexandrina snails and on cercarial production from infected snails were evaluated. In the present study, miracidia of Schistosoma mansoni and S. haematobium were exposed to sublethal concentrations of Luowi/TDS 4% and miracidial mortality rates in the test and control groups were recorded. The effect of exposure to LC10 and LC25 of Luowei/TDS 4% after 1, 2 and 3 weeks of B. alexandrina infection with miracidia on their cercarial production was determined. The molluscicidal activity of 2LC90Luowei/TDS 4% against B. alexandrina and B. truncatus was tested under semi-field and field conditions. Luowei/TDS 4% exhibited a promising molluscicidal potency against B. alexandrina and B. truncatus as their LC90 values were considerably low, 2.851 and 1.936 mg/L, respectively, after 24 h of exposure. Moreover, infection rates of B. alexandrina with S. mansoni and cercarial production from snails exposed to LC10 and LC25 of Luowei/TDS 4% post miracidial exposure were reduced. Moreover, Luowei/TDS 4% at semi-field and field trials proved to be a potent molluscicidal agent against schistosomiasis intermediate host snails as mortality rates of free and caged sentinel snails from these trials were considerably high ranging from 87% to 100% after 24 h of treatment with 5.702 mg/L (2LC90 for B. alexandrina snails). Luowei/TDS 4% should be considered as a candidate molluscicide in schistosomiasis control programs. Implementation of this plant molluscicide in operational schistosomiasis control strategies will minimize the ecological side-effects associated with replacing synesthetic chemicals.

The diversity of fresh water snail fauna in Kiri dam, Adamawa State, North Eastern Nigeria

Abstract: Freshwater Snails are crucial in assessing the ecological status of water bodies, besides their economic, public and veterinary health importance. Hence, the need to study the occurrence, and diversity of freshwater snails in Kiri dam where there is paucity of such information becomes imperative. Accordingly, this study was carried out between December, 2016 and July, 2018. Snails were searched for in the five contact sites identified using long handle metal scoop nets in accordance with standard procedure. Snails recovered were examined for natural infections. Eleven (11) different fresh water snail species were encountered including Bulinus globosus, Bulinus truncatus, Biomphalaria pfeifferi, Lymnaea natalensis, Lanistes ovum, Lanistes varicus, Pila ovata, Melanoides maculata, Melanoides tuberculata, Bellamya unicolor and Gabiella tchadiensis of the eleven different snail species examined, only Bulinus globosus Bulinus truncatus and Biomphalaria pfeifferi shed schistosome cercariae. The other 8 species did not have any natural infections. The study revealed that Kiri Dam harbours diverse species of fresh water snails including those of public health importance. The presence of naturally infected snails indicates that the people engaging in various activities in the dam, are predisposed to infections harboured by these snails.

Resistance of Biomphalaria alexandrina to Schistosoma mansoni and Bulinus truncatus to Schistosoma haematobium Correlates with Unsaturated Fatty Acid Levels in the Snail Soft Tissue.

Abstract: Only a fraction of the Biomphalaria and Bulinus snail community shows patent infection with schistosomes despite continuous exposure to the parasite, indicating that a substantial proportion of snails may resist infection. Accordingly, exterminating the schistosome intermediate snail hosts in transmission foci in habitats that may extend to kilometres is cost-prohibitive and damaging to the ecological equilibrium and quality of water and may be superfluous. It may be more cost effective with risk less ecological damage to focus on discovering the parameters governing snail susceptibility and resistance to schistosome infection. Therefore, laboratory bred Biomphalaria alexandrina and Bulinus truncatus snails were exposed to miracidia of laboratory-maintained Schistosoma mansoni and S. haematobium, respectively. Snails were examined for presence or lack of infection association with soft tissue and hemolymph content of proteins, cholesterol, and triglycerides, evaluated using standard biochemical techniques and palmitic, oleic, linoleic, and arachidonic acid, assayed by ultraperformance liquid chromatography-tandem mass spectrometry. Successful schistosome infection of B. alexandrina and B. truncatus consistently and reproducibly correlated with snails showing highly significant (up to P < 0.0001) decrease in soft tissue and hemolymph content of the monounsaturated fatty acid, oleic acid, and the polyunsaturated fatty acids, linoleic, and arachidonic acids as compared to naive snails. Snails that resisted twice infection had soft tissue content of oleic, linoleic, and arachidonic acid similar to naive counterparts. High levels of soft tissue and hemolymph oleic, linoleic, and arachidonic acid content appear to interfere with schistosome development in snails. Diet manipulation directed to eliciting excessive increase of polyunsaturated fatty acids in snails may protect them from infection and interrupt disease transmission in a simple and effective manner.

Biocidal effect of Nigella sativa, Pelargonium graveolens and Azadirachta indica extracts on Bulinus truncatus snail and aquatic stages of Schistosoma haematobium

Abstract: Background: Schistosomiasis is a public health problem of social and economic importance in thedeveloping world. Schistosomiasis haematobium is still endemic in many foci along the Nile valley,especially in El Fayoum and Beni-Suef governorates. Chemotherapy and snail eradication are the mostimportant control measures with few studies that dealt with its snail intermediate host, Bulinus truncatus.Because of drug resistance and recurrence of exposure to infection, snail control becomes a better methodfor control, keeping in mind that chemical molluscicides may have toxic effects on non-target organisms.Objectives: The aim of the study is to search for biologically derived molluscicides such as plant extracts,that are less expensive, available, biodegradable, non-toxic and easily applicable than synthetic ones.Material and Methods: The effect of oil extracts of three natural plants; Nigella sativa, Pelargoniumgraveolens and Azadirachta indica were investigated as molluscicidal agents against B. truncatus snail.Histopathological examination of the soft tissue of the snail was performed after its removal from the shelland its staining with hematoxylin and eosin (HE). Effect of the three plants on miracidia and cercariae ofS. haematobium was also evaluated.Results: The potent molluscicidal effect was demonstrated by disturbance of normal histology andpresence of vacuolated tissues evident by microscopical examination of the dead snails after HE staining.A schistosomicidal effect was also recorded against aquatic stages of the parasite, demonstrated byreduction in the movement of the miracidia, followed by their sinking down together with the cercariae.N. sativa showed the most potent molluscicidal, miracidicidal, as well as cercaricidal activities, followed byP. graveolens, while A. indica had the least effect.Conclusion: These findings recommend the use of the studied plant extracts as safe and effective agentsin the control of S. haematobium in Egypt.