Showing papers on "Bulinus truncatus published in 2021"

Invasive snails, parasite spillback, and potential parasite spillover drive parasitic diseases of Hippopotamus amphibius in artificial lakes of Zimbabwe.

Abstract: Humans impose a significant pressure on large herbivore populations, such as hippopotami, through hunting, poaching, and habitat destruction. Anthropogenic pressures can also occur indirectly, such as artificial lake creation and the subsequent introduction of invasive species that alter the ecosystem. These events can lead to drastic changes in parasite diversity and transmission, but generally receive little scientific attention. In order to document and identify trematode parasites of the common hippopotamus (Hippopotamus amphibius) in artificial water systems of Zimbabwe, we applied an integrative taxonomic approach, combining molecular diagnostics and morphometrics on archived and new samples. In doing so, we provide DNA reference sequences of the hippopotamus liver fluke Fasciola nyanzae, enabling us to construct the first complete Fasciola phylogeny. We describe parasite spillback of F. nyanzae by the invasive freshwater snail Pseudosuccinea columella, as a consequence of a cascade of biological invasions in Lake Kariba, one of the biggest artificial lakes in the world. Additionally, we report an unknown stomach fluke of the hippopotamus transmitted by the non-endemic snail Radix aff. plicatula, an Asian snail species that has not been found in Africa before, and the stomach fluke Carmyerius cruciformis transmitted by the native snail Bulinus truncatus. Finally, Biomphalaria pfeifferi and two Bulinus species were found as new snail hosts for the poorly documented hippopotamus blood fluke Schistosoma edwardiense. Our findings indicate that artificial lakes are breeding grounds for endemic and non-endemic snails that transmit trematode parasites of the common hippopotamus. This has important implications, as existing research links trematode parasite infections combined with other stressors to declining wild herbivore populations. Therefore, we argue that monitoring the anthropogenic impact on parasite transmission should become an integral part of wildlife conservation efforts.

MALDI-TOF mass spectrometry for the identification of freshwater snails from Senegal, including intermediate hosts of schistosomes.

Abstract: Freshwater snails of the genera Biomphalaria, Bulinus, and Oncomelania are intermediate hosts of schistosomes that cause human schistosomiasis, one of the most significant infectious neglected diseases in the world. Identification of freshwater snails is usually based on morphology and potentially DNA-based methods, but these have many drawbacks that hamper their use. MALDI-TOF MS has revolutionised clinical microbiology and has emerged in the medical entomology field. This study aims to evaluate MALDI-TOF MS profiling for the identification of both frozen and ethanol-stored snail species using protein extracts from different body parts. A total of 530 field specimens belonging to nine species (Biomphalaria pfeifferi, Bulinus forskalii, Bulinus senegalensis, Bulinus truncatus, Bulinus globosus, Bellamya unicolor, Cleopatra bulimoides, Lymnaea natalensis, Melanoides tuberculata) and 89 laboratory-reared specimens, including three species (Bi. pfeifferi, Bu. forskalii, Bu. truncatus) were used for this study. For frozen snails, the feet of 127 field and 74 laboratory-reared specimens were used to validate the optimised MALDI-TOF MS protocol. The spectral analysis yielded intra-species reproducibility and inter-species specificity which resulted in the correct identification of all the specimens in blind queries, with log-score values greater than 1.7. In a second step, we demonstrated that MALDI-TOF MS could also be used to identify ethanol-stored snails using proteins extracted from the foot using a specific database including a large number of ethanol preserved specimens. This study shows for the first time that MALDI-TOF MS is a reliable tool for the rapid identification of frozen and ethanol-stored freshwater snails without any malacological expertise.

Population Dynamics of Intermediate-Host Snails in the White Nile River, Sudan: A Year-Round Observational Descriptive Study

Abstract: We aimed to explore the population dynamics of snail in 3 sites of the White Nile in Sudan. More specifically, we aimed to investigate the annual patterns of snail populations that act as intermediate hosts of schistosomes and monthly snail infection rates and ecological characteristics presumably related to snail populations. We collected snails for 1 year monthly at 3 different shore sites in the vicinity of El Shajara along the White Nile river in Khartoum State, Sudan. In addition, we measured air and water temperatures, water turbidities, vegetation coverages, and water depths and current speeds. Most of the collected snails were Biomphalaria pfeifferi and Bulinus truncatus. The population densities of snails and their infection rates varied across survey sites. The collected snails liberated S. mansoni and S. haematobium cercariae as well as Amphistome and Echinostome cercariae. Infected snails were found during March-June. The ecological characteristics found to be associated with the absence of snails population were: high turbidity, deep water, low vegetation coverage (near absence of vegetation), high water temperature, and high current speed. To our knowledge, this is the first longitudinal study of the snail population and ecological characteristics in the main basin of the White Nile river.

Mitochondrial genome of Bulinus truncatus (Gastropoda: Lymnaeoidea): Implications for snail systematics and schistosome epidemiology

Abstract: Many freshwater snails of the genus Bulinus act as intermediate hosts in the life-cycles of schistosomes in Africa and adjacent regions. Currently, 37 species of Bulinus representing four groups are recognised. The mitochondrial cytochrome c oxidase subunit 1 (cox1) gene has shown utility for identifying and differentiating Bulinus species and groups, but taxonomic relationships based on genetic data are not entirely consistent with those inferred using morphological and biological features. To underpin future systematic studies of members of the genus, we characterised here the mitochondrial genome of Bulinus truncatus (from a defined laboratory strain) using a combined second- and third-generation sequencing and informatics approach, enabling taxonomic comparisons with other planorbid snails for which mitochondrial (mt) genomes were available. Analyses showed consistency in gene order and length among mitochondrial genomes of representative planorbid snails, with the lowest and highest nucleotide diversities being in the cytochrome c oxidase and nicotinamide dehydrogenase subunit genes, respectively. This first mt genome for a representative of the genus Bulinus should provide a useful resource for future investigations of the systematics, population genetics, epidemiology and/or ecology of Bulinus and related snails. The sequencing and informatic workflow employed here should find broad applicability to a range of other snail intermediate hosts of parasitic trematodes.

Impact of the photosensitizers copper and magnesium chlorophyllin on biological and biochemical parameters of Bulinus truncatus snail

Abstract: Bulinus truncatus snail is the intermediate host of Schistosoma haematobium, which causes serious damage to the urinary system of infected patients. To control it in its rapid interruption and/or elimination of the disease transmission would be efficient. Copper chlorophyllin (Cu-chl) and magnesium chlorophyllin (Mg-chl); two photosensitizers used in several biological applications, were bio-assayed against B. truncatus snails. Mg-chl proved to be more toxic to the snails than Cu-chl; their LC90 values were 516.7 and 668.9 ppm, respectively. The sub lethal concentrations of each photosensitizer significantly suppressed the fecundity (Mx) and reproductive rate (R0) of treated snails, which could be partially attributed to the recorded disturbances in their biochemical parameters. The reduction rates of R0 for snails treated with LC25 Mg-chl and Cu-chl were 83.5% and 50.8%, respectively. Moreover, these photosensitizers exerted marked histological changes in the hermaphrodite gland of treated snails where spermatogonia and oogonia in the gland acini were degenerated, while the connective tissue was disintegrated. Both Mg-chl and Cu-chl exhibited toxic effect on B. truncatus snail and interfered with the biological parameters of it that could negatively interrupt the transmission of S. haemeatobium. Therefore, both chemicals could be considered in the control program of this parasite being cheap and environmentally safe.

Species diversity and distribution of schistosome intermediate snail hosts in The Gambia.

Abstract: There is a need for recent information on intermediate snail hosts of schistosomes in The Gambia as the latest studies were conducted over three decades ago. This study assessed the incidence, species diversity, distribution and infection status of schistosome intermediate snail hosts in the country. Malacological surveys were conducted in all 5 regions of The Gambia: Central River Region (CRR), Upper River Region (URR), Western Region (WR), Lower River Region (LRR) and North Bank Region (NBR). Sampling of snails was undertaken at 114 sites that included permanent water bodies such as streams (bolongs), rice fields, irrigation canals and swamps; and temporal (seasonal) laterite pools. Ecological and physicochemical factors of sites were recorded. Snails were identified morphologically and screened for schistosome infections using molecular techniques. Freshwater snails were found at more than 50% (60/114) of sites sampled. While three species of Bulinus were collected, no Biomphalaria snails were found in any of the sites sampled. Of the total 2877 Bulinus snails collected, 75.9% were identified as Bulinus senegalensis, 20.9% as Bulinus forskalii and 3.2% as Bulinus truncatus. Seasonal pools produced the largest number of snails, and CRR was the region with the largest number of snails. Bulinus senegalensis was found more in seasonal pools as opposed to permanent sites, where B. forskalii and B. truncatus were observed to thrive. Bulinus snails were more common in seasonal sites where aquatic vegetation was present. In permanent sites, the abundance of snails increased with increase in water temperature and decrease in water pH. Bulinus senegalensis was found infected with both S. haematobium and S. bovis, while B. forskalii and B. truncatus had only S. bovis infection. While the human parasite S. haematobium was restricted to just four sites, the livestock parasite S. bovis had a much more widespread geographical distribution across both CRR and URR. This new information on the distribution of intermediate snail hosts of schistosomes in The Gambia will be vital for the national schistosomiasis control initiative.

Bulinus truncatus transcriptome – a resource to enable molecular studies of snail and schistosome biology

Abstract: Despite advances in high-throughput sequencing and bioinformatics, molecular investigations of snail intermediate hosts that transmit parasitic trematodes are scant. Here, we report the first transcriptome for Bulinus truncatus – a key intermediate host of Schistosoma haematobium – a blood fluke that causes urogenital schistosomiasis in humans. We assembled this transcriptome from short- and long-read RNA-sequence data. From this transcriptome, we predicted 12,998 proteins, 58% of which had orthologs in Biomphalaria glabrata – an intermediate host of Schistosoma mansoni – a blood fluke that causes hepato-intestinal schistosomiasis. We predicted that select protein groups are involved in signal transduction, cell growth and death, the immune system, environmental adaptation and/or the excretory/secretory system, suggesting roles in immune responses, pathogen defence and/or parasite-host interactions. The transcriptome of Bu. truncatus provides a useful resource to underpin future molecular investigations of this and related snail species, and its interactions with pathogens including S. haematobium. The present resource should enable comparative investigations of other molluscan hosts of socioeconomically important parasites in the future.

Evaluation of molluscicidal, miracicidal and cercaricidal activities of crude aqueous extracts of Origanum majorana, Ziziphus spina-christi and Salvia fruticosa on Schistosoma mansoni and Schistosoma haematobium

Abstract: Schistosomiasis has been classified as a category II disease after malaria in importance as a targeted tropical disease. Praziquantel (PZQ) which is the chemotherapeutic agent of choice against adult worms, already faces drawback of drug resistance in some Schistosoma isolates. Therefore, searching for new alternative drugs has been the intention of many researchers. In the current study, the effect of different doses 6.25, 12.5, 25. 50. 100 and 200 mg/ml of Origanum majorana,Ziziphus spina-christi, and Salvia fruticosa extracts on the snails Bulinus truncatus of the S. haematobium and Biomphalaria alexandrina of the Schistosoma mansoni as well as on the free-living stages miracidia, in addition, the cercariae for both Egyptian species of schistosomes were studied. The results declared that Origanum majorana,Ziziphus spina-christi showed efficacy against snails (molluscicidal), miracidia (miracicidal), and cercariae (cercaricidal) for both Egyptian species of schistosomes in the in vitro, while Salvia fruticosa was less effective than the previous ones

Impact of carbamide perhydrate on the snail Bulinus truncatus, the intermediate host of Schistosoma haematobium

Abstract: Schistosomiasis is considered a tropical parasitic disease of poverty caused by certain blood flukes of the genus Schistosoma, which induces cerious health problems to infected humans and it is transmitted by specific snail species present in irrigation systems (WHO, 2017). The three major forms of human shistosomiasis are S. mansoni, S. haematbium and S. japonicum transmitted by the snail intermediate hosts of the genera Biomphlaria, Bulinus and Oncomelania, respectively (Malek & Cheng, 1974). The prevalence of schistosomiasis is rapidly increasing with the extension of water development projects (Yapi et al 2005).

Aqueous Extracts: An Alternative in the Control of the Intermediate Host of Schistosomiasis

Abstract: Schistosomiasis is a parasitic disease caused by worms of the genus Schistosoma. Some substances are used to control the intermediate host, being a strategy to prevent the risk of infection and re-infection of the disease. According to the WHO, the recommended substance is Niclosamide; however, it presents toxicity in non-target organisms. Aqueous extracts are being increasingly studied as a potential molluscicide in combating schistosomiasis. The aqueous extract of Moringa oleifera flowers was used to evaluate the molluscicidal activity in Biomphalaria glabrata. This extract caused lethality in adult molluscs, obtaining a lethal concentration 50 = 2.37 mg/mL. In the second aqueous extract, fruits of the species Randia nilotica were used on molluscs of the species Biomphalaria pfeifferi and Bulinus truncatus. These extracts showed molluscicidal activity on both molluscs used in the experiments. In the third aqueous extract, they used leaves of the species Anagallis arvensis to test the molluscicidal action on molluscs of the species Biomphalaria alexandrina. It was possible to obtain lethal concentrations, with lethal concentration 50 = 37.9 mg/L and lethal concentration 90 = 48.3 mg/L. In the fourth aqueous extract, they used the seeds of the species Moringa oleifera to evaluate the molluscicidal activity in molluscs of the genus Bulinus. These seeds showed molluscicidal action, but they were not in accordance with what is recommended by the WHO. According to the experiments carried out with aqueous extracts, it can be seen that there are many studies using these methodologies as a form of control for schistosomiasis. Some criteria are essential to obtain a low-cost aqueous extract. It is essential to emphasize that this methodology could be used by the government to control the intermediate host of schistosomiasis in less favored areas, where the population itself would have access to inputs using accessible technological resources.