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1.
Infect Dis Poverty ; 13(1): 65, 2024 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-39256885

RESUMEN

BACKGROUND: Combating infectious diseases and halting biodiversity loss are intertwined challenges crucial to ensure global health. Biodiversity can constrain the spread of vector-borne pathogens circulation, necessitating a deeper understanding of ecological mechanisms underlying this pattern. Our study evaluates the relative importance of biodiversity and the abundance of Bulinus truncatus, a major intermediate host for the trematode Schistosoma haematobium on the circulation of this human pathogen at aquatic transmission sites. METHODS: We combined mathematical modelling and a molecular based empirical study to specifically assess the effect of co-infections between S. haematobium and other trematodes within their B. truncatus snail hosts; and B. truncatus abundance at transmission sites, on the production of S. haematobium infective cercariae stages released into the aquatic environment. RESULTS: Our modelling approach shows that more competitive trematode species exploiting B. truncatus as an intermediate host at the transmission site level leads to higher co-infection rates within snail hosts, subsequently reducing the production of S. haematobium cercariae. Conversely, an increase in B. truncatus abundance results in lower co-infection rates, and a higher proportion of S. haematobium cercariae released into the environment. Our empirical data from the field support these findings, indicating a significant negative effect of local trematode species richness (P-value = 0.029; AIC = 14.9) and co-infection rates (P-value = 0.02, AIC = 17.4) on the dominance of S. haematobium based on our GLMM models, while B. truncatus abundance positively influences S. haematobium dominance (P-value = 0.047, AIC = 20.1). CONCLUSIONS: Our study highlights the importance of biodiversity in influencing the transmission of S. haematobium through the effect of antagonistic interactions between trematodes within bulinid snail hosts. This effect intensifies when B. truncatus populations are low, promoting co-infections within snails. In line with the One Health concept, our results suggest that maintaining high level of freshwater biodiversity to sustain global trematode diversity at transmission sites can help reducing the circulation of Schistosoma species locally.


Asunto(s)
Interacciones Huésped-Parásitos , Schistosoma haematobium , Trematodos , Animales , Schistosoma haematobium/fisiología , Trematodos/fisiología , Humanos , Esquistosomiasis Urinaria/transmisión , Esquistosomiasis Urinaria/parasitología , Bulinus/parasitología , Caracoles/parasitología , Biodiversidad , Coinfección/parasitología , Modelos Teóricos , Cercarias/fisiología
2.
Infect Dis Poverty ; 13(1): 63, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39218903

RESUMEN

BACKGROUND: The control of schistosomiasis is particularly difficult in sub-Saharan Africa, which currently harbours 95% of this disease. The target population for preventive chemotherapy (PC) is expanded to all age group at risk of infection, thus increasing the demands of praziquantel (PZQ) tablets according to the new released guideline by World Health Organization. Due to the gap between available PZQ for PC and requirements, alternative approaches to assess endemicity of schistosomiasis in a community, are urgently needed for more quick and precise methods. We aimed to find out to which degree the infection status of snails can be used to guide chemotherapy against schistosomiasis. METHODS: We searched literature published from January 1991 to December 2022, that reported on the prevalence rates of Schistosoma mansoni, S. haematobium in the intermediate snails Biomphalaria spp. and Bulinus spp., respectively, and in humans. A random effect model for meta-analyses was used to calculate the pooled prevalence estimate (PPE), with heterogeneity assessed using I-squared statistic (I2), with correlation and regression analysis for the exploration of the relationship between human S. mansoni and S. haematobium infections and that in their specific intermediate hosts. RESULTS: Forty-seven publications comprising 59 field investigations were included. The pooled PPE of schistosomiasis, schistosomiasis mansoni and schistosomiasis haematobium in humans were 27.5% [95% confidence interval (CI): 24.0-31.1%], 25.6% (95% CI: 19.9-31.3%), and 28.8% (95% CI: 23.4-34.3%), respectively. The snails showed an overall infection rate of 8.6% (95% CI: 7.7-9.4%), with 12.1% (95% CI: 9.9-14.2%) in the Biomphalaria spp. snails and 6.9% (95% CI: 5.7-8.1%) in the Bulinus spp. snails. The correlation coefficient was 0.3 (95% CI: 0.01-0.5%, P < 0.05) indicating that the two variables, i.e. all intermediate host snails on the one hand and the human host on the other, were positively correlated. CONCLUSIONS: The prevalence rate of S. mansoni and S. haematobium is still high in endemic areas. Given the significant, positive correlation between the prevalence of schistosomes in humans and the intermediate snail hosts, more attention should be paid to programme integration of snail surveillance in future.


Asunto(s)
Biomphalaria , Schistosoma haematobium , Schistosoma mansoni , Esquistosomiasis Urinaria , Esquistosomiasis mansoni , Animales , Humanos , Prevalencia , Esquistosomiasis mansoni/epidemiología , Esquistosomiasis mansoni/prevención & control , Esquistosomiasis mansoni/parasitología , Esquistosomiasis Urinaria/epidemiología , Esquistosomiasis Urinaria/prevención & control , Esquistosomiasis Urinaria/parasitología , Schistosoma haematobium/fisiología , Schistosoma mansoni/fisiología , Biomphalaria/parasitología , Caracoles/parasitología , Bulinus/parasitología , África del Sur del Sahara/epidemiología
3.
Glob Chang Biol ; 30(8): e17434, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39105284

RESUMEN

The freshwater snail Bulinus truncatus is an important intermediate host for trematode parasites causing urogenital schistosomiasis, a tropical disease affecting over 150 million people. Despite its medical importance, uncertainty remains about its global distribution and the potential impacts of climate change on its future spread. Here, we investigate the distribution of B. truncatus, combining the outputs of correlative and mechanistic modelling methods to fully capitalize on both experimental and occurrence data of the species and to create a more reliable distribution forecast than ever constructed. We constructed ensemble correlative species distribution models using 273 occurrence points collected from different sources and a combination of climatic and (bio)physical environmental variables. Additionally, a mechanistic thermal suitability model was constructed, parameterized by recent life-history data obtained through extensive lab-based snail-temperature experiments and supplemented with an extensive literature review. Our findings reveal that the current suitable habitat for B. truncatus encompasses the Sahel region, the Middle East, and the Mediterranean segment of Africa, stretching from Southern Europe to Mozambique. Regions identified as suitable by both methods generally coincide with areas exhibiting high urogenital schistosomiasis prevalence. Model projections into the future suggest an overall net increase in suitable area of up to 17%. New suitable habitat is in Southern Europe, the Middle East, and large parts of Central Africa, while suitable habitat will be lost in the Sahel region. The change in snail habitat suitability may substantially increase the risk of urogenital schistosomiasis transmission in parts of Africa and Southern Europe while reducing it in the Sahel region.


Asunto(s)
Cambio Climático , Esquistosomiasis Urinaria , Animales , Europa (Continente) , Esquistosomiasis Urinaria/transmisión , Esquistosomiasis Urinaria/epidemiología , África/epidemiología , Bulinus/parasitología , Ecosistema , Humanos , Caracoles/parasitología , Caracoles/fisiología , Distribución Animal , Modelos Teóricos
4.
Parasit Vectors ; 17(1): 272, 2024 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-38937778

RESUMEN

BACKGROUND: Along the southern shoreline of Lake Malawi, the incidence of schistosomiasis is increasing with snails of the genera Bulinus and Biomphalaria transmitting urogenital and intestinal schistosomiasis, respectively. Since the underlying distribution of snails is partially known, often being focal, developing pragmatic spatial models that interpolate snail information across under-sampled regions is required to understand and assess current and future risk of schistosomiasis. METHODS: A secondary geospatial analysis of recently collected malacological and environmental survey data was undertaken. Using a Bayesian Poisson latent Gaussian process model, abundance data were fitted for Bulinus and Biomphalaria. Interpolating the abundance of snails along the shoreline (given their relative distance along the shoreline) was achieved by smoothing, using extracted environmental rainfall, land surface temperature (LST), evapotranspiration, normalised difference vegetation index (NDVI) and soil type covariate data for all predicted locations. Our adopted model used a combination of two-dimensional (2D) and one dimensional (1D) mapping. RESULTS: A significant association between normalised difference vegetation index (NDVI) and abundance of Bulinus spp. was detected (log risk ratio - 0.83, 95% CrI - 1.57, - 0.09). A qualitatively similar association was found between NDVI and Biomphalaria sp. but was not statistically significant (log risk ratio - 1.42, 95% CrI - 3.09, 0.10). Analyses of all other environmental data were considered non-significant. CONCLUSIONS: The spatial range in which interpolation of snail distributions is possible appears < 10km owing to fine-scale biotic and abiotic heterogeneities. The forthcoming challenge is to refine geospatial sampling frameworks with future opportunities to map schistosomiasis within actual or predicted snail distributions. In so doing, this would better reveal local environmental transmission possibilities.


Asunto(s)
Biomphalaria , Bulinus , Lagos , Esquistosomiasis , Animales , Malaui/epidemiología , Lagos/parasitología , Biomphalaria/parasitología , Bulinus/parasitología , Esquistosomiasis/epidemiología , Esquistosomiasis/transmisión , Esquistosomiasis/parasitología , Análisis Espacial , Humanos , Teorema de Bayes , Caracoles/parasitología , Vectores de Enfermedades
5.
PLoS Negl Trop Dis ; 18(6): e0011836, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38857289

RESUMEN

The geographical range of schistosomiasis is affected by the ecology of schistosome parasites and their obligate host snails, including their response to temperature. Previous models predicted schistosomiasis' thermal optimum at 21.7°C, which is not compatible with the temperature in sub-Saharan Africa (SSA) regions where schistosomiasis is hyperendemic. We performed an extensive literature search for empirical data on the effect of temperature on physiological and epidemiological parameters regulating the free-living stages of S. mansoni and S. haematobium and their obligate host snails, i.e., Biomphalaria spp. and Bulinus spp., respectively. We derived nonlinear thermal responses fitted on these data to parameterize a mechanistic, process-based model of schistosomiasis. We then re-cast the basic reproduction number and the prevalence of schistosome infection as functions of temperature. We found that the thermal optima for transmission of S. mansoni and S. haematobium range between 23.1-27.3°C and 23.6-27.9°C (95% CI) respectively. We also found that the thermal optimum shifts toward higher temperatures as the human water contact rate increases with temperature. Our findings align with an extensive dataset of schistosomiasis prevalence in SSA. The refined nonlinear thermal-response model developed here suggests a more suitable current climate and a greater risk of increased transmission with future warming for more than half of the schistosomiasis suitable regions with mean annual temperature below the thermal optimum.


Asunto(s)
Schistosoma haematobium , Schistosoma mansoni , Temperatura , Animales , Humanos , Schistosoma haematobium/fisiología , Schistosoma mansoni/fisiología , África del Sur del Sahara/epidemiología , Biomphalaria/parasitología , Esquistosomiasis/transmisión , Esquistosomiasis/epidemiología , Esquistosomiasis mansoni/transmisión , Esquistosomiasis mansoni/epidemiología , Bulinus/parasitología , Esquistosomiasis Urinaria/transmisión , Esquistosomiasis Urinaria/epidemiología , Prevalencia
6.
Folia Parasitol (Praha) ; 712024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38841845

RESUMEN

Schistosomiasis is a snail-borne disease that has a considerable impact on human and animal health, particularly in sub-Saharan Africa. The intermediate hosts of the schistosome parasites are freshwater snails of the genera Biomphalaria Preston, 1910 and Bulinus Müller, 1781. In order to identify existing gaps in the spread of the disease in the Democratic Republic of Congo (DRC), this study compiled the available knowledge of the distribution, population dynamics and ecology of the intermediate hosts of schistosomiasis. A systematic literature search was conducted in PubMed, Embase and Scopus for all malacological studies on schistosoma intermediate hosts in DRC published between 1927 and October 2022. A total of 55 records were found, of which 31 met the inclusion criteria: these were published field and experimental studies conducted in the DRC and focused on snails as intermediate hosts of schistosomes. The analysis of these studies revealed that more up-to-date data on the distribution of snail intermediate hosts in the DRC are needed. Moreover, ecological factors have been less studied for Bulinus species than for Biomphalaria species. These factors play a crucial role in determining suitable snail habitats, and the lack of comprehensive information poses a challenge in snail control. This review makes it clear that there are no current malacological data in the DRC. There is a clear need for molecular and ecological research to update the exact species status and population dynamics of all potential intermediate host species. This will facilitate targeted snail control measures that complement drug treatment in the control of schistosomiasis in the country.


Asunto(s)
Biomphalaria , Esquistosomiasis , Animales , Humanos , Biomphalaria/parasitología , Bulinus/parasitología , República Democrática del Congo/epidemiología , Schistosoma/fisiología , Esquistosomiasis/epidemiología , Esquistosomiasis/veterinaria , Caracoles/parasitología
7.
PLoS Negl Trop Dis ; 18(4): e0012062, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38574112

RESUMEN

INTRODUCTION: Schistosomiasis and fasciolosis are snail-borne diseases of great medical and veterinary health importance. The World Health Organization recommends complementing drug treatment with snail control and community involvement for disease elimination, but there is a general lack of snail experts and hence snail distribution data. Therefore, we adopted a citizen science approach and involved citizens in the monitoring of medically and veterinary important snail taxa. MATERIALS AND METHODS: Snail data was collected weekly by 25 trained citizen scientists (CSs) at 76 sites around southern Lake Albert (Uganda) for 20 months. At each site, snails were searched for 30 minutes, sorted, target snail hosts identified to genus level, counted and data submitted through a smartphone application. The quality of this data was assessed by comparing it to monthly data collected by an 'expert' malacologist using the same sampling protocol. Generalised binomial logistic and linear mixed-effects models were used to analyse the variables for agreement between the CSs and expert. FINDINGS: The binary agreement in presence/absence of Biomphalaria, Bulinus and Radix snails reported by the expert and CSs ranged between 70% and 86% (900 reports) with an average of 17% false negatives (sites wrongly defined as snail-free). The agreement for Biomphalaria and Radix increased with snail abundance, and false negatives decreased when the number of snails collected by citizens was aggregated per month. Site type significantly predicted binary agreement, which was lowest at lake sites (55%) and highest at spring sites (99%) with variations across genera. Similar temporal trends in snail abundance were recorded despite the expert reporting higher abundance. However, the relative abundance was consistent across site types. The match between the sites with highest Biomphalaria spp. abundance identified by CSs and expert was consistently high (~84.1%) and increased over time. CONCLUSIONS AND RECOMMENDATIONS: Our results demonstrate the potential of citizen science to map putative schistosomiasis transmission sites. We therefore argue that this inclusive, powerful and cost-effective approach can be more sustainable than top-down monitoring and intervention campaigns.


Asunto(s)
Biomphalaria , Esquistosomiasis , Animales , Humanos , Esquistosomiasis/epidemiología , Bulinus , Estaciones del Año , Vectores de Enfermedades
8.
Acta Parasitol ; 69(1): 1016-1026, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38502474

RESUMEN

PURPOSE: Accurate identification of medically important intermediate host and vector species is crucial for understanding disease transmission and control. Identifying Bulinus snails which act as intermediate host species for the transmission of schistosomiasis is typically undertaken using conchological and genital morphology as well as molecular methods. METHODS: Here, a landmark-based morphometric analysis of shell morphology was undertaken to determine its utility to distinguish the closely related and morphologically similar sister species Bulinus senegalensis and Bulinus forskalii. The method was developed to increase the accuracy of conchological morphology methods to identify Bulinus species in the field. Both species are found in West Africa, but only B. senegalensis is implicated in the transmission of urogenital schistosomiasis. RESULTS: We found when scaled down to the same length, 3-whorl and 4-whorl (juvenile) B. senegalensis shells had a longer spire, narrower body whorl and shorter aperture than B. forskalii. In contrast, 5-whorl (adult) B. senegalensis had a shorter spire, but still had a shorter aperture and narrower body whorl than B. forskalii. Canonical Variate Analysis (CVA) showed minimal overlap between B. senegalensis and B. forskalii for 3-whorl and 4-whorl shells, with a clear separation for 5-whorl shells. Overall, B. senegalensis had a consistently shorter aperture size and narrower body whorl than B. forskalii for all development stages. Spire length was variable depending on the stage of development, with 3-whorl and 4-whorl shells having the opposite trends of adult shells. CONCLUSIONS: Our study demonstrates the applicability of landmark-based morphometrics in distinguishing the medically important, Bulinus senegalensis from its morphologically similar sister species, Bulinus forskalii. We recommend using measurements based on spire length, penultimate whorl length, body whorl width and aperture size to differentiate B. senegalensis and B. forskalii, when used with the appropriate information for each shell's development stage.


Asunto(s)
Bulinus , Animales , África Occidental , Bulinus/parasitología , Bulinus/anatomía & histología , Exoesqueleto/anatomía & histología , Especificidad de la Especie
9.
Sci Rep ; 14(1): 4274, 2024 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-38383705

RESUMEN

Schistosomiasis, a prevalent water-borne disease second only to malaria, significantly impacts impoverished rural communities, primarily in Sub-Saharan Africa where over 90% of the severely affected population resides. The disease, majorly caused by Schistosoma mansoni and S. haematobium parasites, relies on freshwater snails, specifically Biomphalaria and Bulinus species, as crucial intermediate host (IH) snails. Targeted snail control is advisable, however, there is still limited knowledge about the community structure of the two genera especially in East Africa. Utilizing a machine learning approach, we employed random forest to identify key features influencing the distribution of both IH snails in this region. Our results reveal geography and climate as primary factors for Biomphalaria, while Bulinus occurrence is additionally influenced by soil clay content and nitrogen concentration. Favorable climate conditions indicate a high prevalence of IHs in East Africa, while the intricate connection with geography might signify either dispersal limitations or environmental filtering. Predicted probabilities demonstrate non-linear patterns, with Bulinus being more likely to occur than Biomphalaria in the region. This study provides foundational framework insights for targeted schistosomiasis prevention and control strategies in the region, assisting health workers and policymakers in their efforts.


Asunto(s)
Biomphalaria , Esquistosomiasis , Humanos , Animales , Esquistosomiasis/epidemiología , Biomphalaria/parasitología , Caracoles , Bulinus/parasitología , África Oriental/epidemiología
10.
Dev Comp Immunol ; 154: 105150, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38367887

RESUMEN

Schistosomiasis, urogenital and intestinal, afflicts 251 million people worldwide with approximately two-thirds of the patients suffering from the urogenital form of the disease. Freshwater snails of the genus Bulinus (Gastropoda: Planorbidae) serve as obligate intermediate hosts for Schistosoma haematobium, the etiologic agent of human urogenital schistosomiasis. These snails also act as vectors for the transmission of schistosomiasis in livestock and wildlife. Despite their crucial role in human and veterinary medicine, our basic understanding at the molecular level of the entire Bulinus genus, which comprises 37 recognized species, is very limited. In this study, we employed Illumina-based RNA sequencing (RNAseq) to profile the genome-wide transcriptome of Bulinus globosus, one of the most important intermediate hosts for S. haematobium in Africa. A total of 179,221 transcripts (N50 = 1,235) were assembled and the benchmarking universal single-copy orthologs (BUSCO) was estimated to be 97.7%. The analysis revealed a substantial number of transcripts encoding evolutionarily conserved immune-related proteins, particularly C-type lectin (CLECT) domain-containing proteins (n = 316), Toll/Interleukin 1-receptor (TIR)-containing proteins (n = 75), and fibrinogen related domain-containing molecules (FReD) (n = 165). Notably, none of the FReDs are fibrinogen-related proteins (FREPs) (immunoglobulin superfamily (IgSF) + fibrinogen (FBG)). This RNAseq-based transcriptional profile provides new insights into immune capabilities of Bulinus snails, helps provide a framework to explain the complex patterns of compatibility between snails and schistosomes, and improves our overall understanding of comparative immunology.


Asunto(s)
Bulinus , Esquistosomiasis Urinaria , Humanos , Animales , Bulinus/genética , Schistosoma haematobium/genética , Agua Dulce , Fibrinógeno
11.
Acta Parasitol ; 69(1): 648-663, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38302641

RESUMEN

BACKGROUND: Trematode infections of the genus Schistosoma can induce physiological and behavioral changes in intermediate snail hosts. This is because the parasite consumes essential resources necessary for the host's survival, prompting hosts to adapt their behavior to maintain some level of fitness before parasite-induced mortality occurs. METHODS: In this study, the reproductive and biochemical parameters of Biomphalaria alexandrina and Bulinus truncatus were examined during the cercareal shedding stage of infection with Schistosoma mansoni and Schistosoma haematobium, respectively, compared with controls. RESULTS: The study revealed an infection rate of 34.7% for S. mansoni and 30.4% for S. haematobium. In B. alexandrina infected with S. mansoni, a survival rate of 65.2% was recorded, along with a mean prepatent period of 30.3 ± 1.41 days, a mean shedding duration of 14.2 ± 0.16 days, and a mean lifespan of 44.1 ± 0.24 days. Meanwhile, in B. truncatus infected with S. haematobium, a survival rate of 56.4% was observed, with a mean prepatent period of 44.3 ± 1.41 days, a mean shedding duration of 22.6 ± 2.7 days, and a mean lifespan of 66.9 ± 1.6 days. Feeding increased in both infected species of snails, while the net reproductive rate (Ro) of the infected snails decreased. Total antioxidant (TAO) and lipid peroxidation activity increased in the two infected snail species during shedding, while Glutathione-S-transferase levels decreased. Lipid peroxidase activity and nitrogen oxide levels significantly decreased in infected B. alexandrina and increased in infected Bulinus. Steroid hormone levels were elevated in infected Biomphalaria, whereas they were reduced in infected Bulinus. Comet assay parameters showed an increase in the two infected genera after infection compared to control snails, indicating genotoxic damage and histopathological damage was observed. CONCLUSIONS: These findings demonstrate that infection with larva species diverse biochemical, hormonal, genotoxic, and histopathological changes in the tissues responsible for fecundity and reproduction in B. alexandrina and B. truncates comparing with controls.


Asunto(s)
Biomphalaria , Bulinus , Interacciones Huésped-Parásitos , Schistosoma mansoni , Animales , Biomphalaria/parasitología , Schistosoma mansoni/fisiología , Bulinus/parasitología , Schistosoma haematobium/genética , Schistosoma haematobium/fisiología , Conducta Alimentaria , Cercarias/fisiología , Reproducción
12.
Infect Dis Poverty ; 13(1): 11, 2024 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-38281969

RESUMEN

BACKGROUND: Freshwater snails of the genera Bulinus spp., Biomphalaria spp., and Oncomelania spp. are the main intermediate hosts of human and animal schistosomiasis. Identification of these snails has long been based on morphological and/or genomic criteria, which have their limitations. These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach. Recently, Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF) mass spectrometry, a new tool used which is routinely in clinical microbiology, has emerged in the field of malacology for the identification of freshwater snails. This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskalii snail populations according to their geographical origin. METHODS: This study was conducted on 101 Bi. pfeifferi and 81 Bu. forskalii snails collected in three distinct geographical areas of Senegal (the North-East, South-East and central part of the country), and supplemented with wild and laboratory strains. Specimens which had previously been morphologically described were identified by MALDI-TOF MS [identification log score values (LSV) ≥ 1.7], after an initial blind test using the pre-existing database. After DNA-based identification, new reference spectra of Bi. pfeifferi (n = 10) and Bu. forskalii (n = 5) from the geographical areas were added to the MALDI-TOF spectral database. The final blind test against this updated database was performed to assess identification at the geographic source level. RESULTS: MALDI-TOF MS correctly identified 92.1% of 101 Bi. pfeifferi snails and 98.8% of 81 Bu. forskalii snails. At the final blind test, 88% of 166 specimens were correctly identified according to both their species and sampling site, with LSVs ranging from 1.74 to 2.70. The geographical source was adequately identified in 90.1% of 91 Bi. pfeifferi and 85.3% of 75 Bu. forskalii samples. CONCLUSIONS: Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin. It outperforms the current DNA-based approaches in discriminating laboratory from wild strains. This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.


Asunto(s)
Biomphalaria , Esquistosomiasis , Animales , Humanos , Bulinus , Esquistosomiasis/epidemiología , Caracoles , Espectrometría de Masas , ADN , Rayos Láser
13.
Microsc Res Tech ; 87(2): 306-314, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37800693

RESUMEN

Schistosomiasis is one of the most common waterborne parasite illnesses, it is a major public health issue in developing countries. The polymerase chain reaction (PCR) technique is used to find Schistosoma haematobium DNA in Bulinus truncatus, which could speed up the discovery of infections before cercariae are shed. DraI-PCR detected S. haematobium infection at different infection intervals with bands at 300 bp in shedding snails 40 days after exposure and even on the first day after B. turancuts snails exposure to miracidia. Transmission electron microscopy showed the structure of sporocyst from 1 to 40 days post-exposure and activated hemocytes in infected non-shedding snails as well as sporocyst degradation. Flow cytometry was used to measure the percentage of Bax and TGF-ß1 positive stained cells that have been linked with infection progression. In conclusion, molecular tools and immune response play an important role in the strategy of controlling schistosomiasis through the early detection of larval stages in intermediate hosts toward certification of schistosomiasis elimination. RESEARCH HIGHLIGHTS: DraI-PCR allowed early detection of S. haematobium at 300 bp in B. truncatus snail. Transmission electron microscopy showed the structure of S. haematobium sporocyst in snail and activated hemocytes in non-shedding snail. Bax protein that induced apoptotic changes and Transforming Growth Factor Beta1 level have been linked with parasite development.


Asunto(s)
Bulinus , Esquistosomiasis , Animales , Bulinus/parasitología , Schistosoma haematobium/genética , Caracoles/parasitología , Inmunidad
14.
Parasitol Int ; 99: 102830, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38016629

RESUMEN

BACKGROUND: The construction of Lake Kariba brought about a rise in the incidence of schistosomiasis in its surrounding towns of Kariba (Zimbabwe) and Siavonga (Zambia). After extensive control programs in Kariba, schistosomiasis prevalence dropped significantly. The objective of this study was to revisit the same localities sampled by Chimbari et al. (2003), and provide an update on the snail community and prevalence of trematodes in the Northern shore of Lake Kariba while focusing on planorbid species. METHODS: Monthly sampling of snails at 16 sites along the Northern shoreline of Lake Kariba, near Kariba town, was undertaken for one year. Minimum one specimen per morphotype was identified using molecular barcoding (sequencing a fragment of cytochrome c oxidase I subunit (COI)). The infection status of snails was assessed by Rapid Diagnostic PCRs (RD-PCR), and trematode infections were genotyped by sequencing COI and 18S rDNA markers. RESULTS: We collected and identified seven snail species: Bulinus truncatus, Bulinus forskalii, Gyraulus sp., Physella acuta, Bellamya sp., Radix affinis plicatula and Pseudosuccinea columella. Physella acuta was the most abundant snail species (comprising 56.95% of the total snail count) and present at all sites. The B. truncatus population was found to be infected with the stomach fluke Carmyerius cruciformis, a Petasiger sp. and a trematode species belonging to the family Notocotylidae. No Schistosoma sp. infections were detected in our collected snail specimens. CONCLUSIONS: We report B. truncatus as an intermediate snail host for Carmyerius cruciformis, and the presence of three non-schistosome trematode species that have not been reported in Lake Kariba before. Furthermore, we detect a possible shift in the snail community when compared to the report by Chimbari et al. (2003): this is the first record of Gyraulus sp. in Lake Kariba, and we did not observe the previously reported B. pfeifferi, B. globosus and Radix natalensis. Although this shift in snail communities might have contributed to the absence of Schistosoma spp. detection in this study, further monitoring of final and intermediate hosts across the Kariba basin is essential to prove a decrease of schistosomiasis in the area.


Asunto(s)
Esquistosomiasis , Trematodos , Animales , Lagos , Trematodos/genética , Bulinus , Esquistosomiasis/epidemiología , Schistosoma/genética
15.
Parasit Vectors ; 16(1): 453, 2023 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-38093363

RESUMEN

Schistosomiasis, the second largest parasitic disease in the world after malaria, poses a significant threat to human health and causes public health issues. The disease primarily affects populations in economically underdeveloped tropical regions, earning it the title of "neglected tropical disease". Schistosomiasis is difficult to eradicate globally if medication alone is used. One of the essential elements of thorough schistosomiasis prevention and control is the management and disruption of the life cycle of intermediate host snails. The key approach to controlling the transmission of schistosomiasis is to control the intermediate hosts of the schistosome to disrupt its life cycle. We believe that approaching it from the perspective of the intermediate host's immunity could be an environmentally friendly and potentially effective method. Currently, globally significant intermediate host snails for schistosomes include Oncomelania hupensis, Biomphalaria glabrata, and Bulinus truncatus. The immune interaction research between B. glabrata and Schistosoma mansoni has a history of several decades, and the complete genome sequencing of both B. glabrata and B. truncatus has been accomplished. We have summarized the immune-related factors and research progress primarily studied in B. glabrata and B. truncatus and compared them with several humoral immune factors that O. hupensis research focuses on: macrophage migration inhibitory factor (MIF), Toll-like receptors (TLRs), and thioredoxin (Trx). We believe that continued exploration of the immune interactions between O. hupensis and Schistosoma japonicum is valuable. This comparative analysis can provide some direction and clues for further in-depth research. Comparative immunological studies between them not only expand our understanding of the immune defense responses of snails that act as intermediaries for schistosomes but also facilitate the development of more comprehensive and integrated strategies for schistosomiasis prevention and control. Furthermore, it offers an excellent opportunity to study the immune system of gastropods and their co-evolution with pathogenic organisms.


Asunto(s)
Biomphalaria , Schistosoma japonicum , Esquistosomiasis , Animales , Humanos , Schistosoma japonicum/genética , Esquistosomiasis/parasitología , Biomphalaria/parasitología , Bulinus , Schistosoma mansoni
16.
Parasit Vectors ; 16(1): 398, 2023 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-37919743

RESUMEN

BACKGROUND: Urogenital schistosomiasis caused by the parasitic blood fluke Schistosoma haematobium is the most common form of that constitutes a majority of over 240 million schistosomiasis cases. The enigmatic absence of urogenital schistosomiasis in Uganda has, until now, been attributed to the absence of substantial populations of suitable snail intermediate hosts. METHODS: Malacological surveys were carried out in 73 sites southeast of Lake Albert, Uganda in October and November 2020. Collected snails were transported to the laboratory for identification. The snails were identified using partial mitochondrial cytochrome c oxidase subunit one and nuclear internal transcribed spacer barcoding. Schistosome infections in snails were also assessed using cercarial shedding and rapid diagnostic PCR techniques. RESULTS: We found Bulinus globosus and Bulinus nasutus productus, the main intermediate species in the transmission of S. haematobium in mainland East Africa. In this survey, B. globosus was more common than B. nasutus productus, with the former reported at four sites (total count = 188) and the latter reported at one site (total count = 79). Molecular testing revealed a high prevalence of Schistosoma bovis in B. nasutus productus (16%), but no S. haematobium infections were found. CONCLUSIONS: Given the abundance of snail hosts and the risky human water contact behaviours observed, we highlight the potential for urogenital schistosomiasis transmission in the region.


Asunto(s)
Esquistosomiasis Urinaria , Animales , Humanos , Lagos , Uganda/epidemiología , Schistosoma haematobium/genética , Bulinus/parasitología
17.
PLoS One ; 18(11): e0295149, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38033142

RESUMEN

Schistosomiasis is a vector-borne disease transmitted by freshwater snails and is prevalent in rural areas with poor sanitation and no access to tap water. Three snail species are known to transmit schistosomiasis in South Africa (SA), namely Biomphalaria pfeifferi, Bulinus globosus and Bulinus africanus. In 2003, a predicted prevalence of 70% was reported in tropical climates in SA. Temperature and rainfall variability can alter schistosomiasis-transmitting snails' development by increasing or decreasing their abundance and geographical distribution. This study aimed to map the historical distribution of schistosomiasis from 1950 to 2006 in SA. The snail sampling data were obtained from the historical National Snail Freshwater Collection (NFSC). Bioclimatic variables were extracted using ERA 5 reanalysis data provided by the Copernicus Climate Change Service. In this study, we used 19 bioclimatic and four soil variables. The temporal aggregation was the mean climatological period pre-calculated over the 40-year reference period with a spatial resolution of 0.5° x 0.5°. Multicollinearity was reduced by calculating the Variance Inflation Factor Core (VIF), and highly correlated variables (> 0.85) were excluded. To obtain an "ensemble" and avoid the integration of weak models, we averaged predictions using the True Skill Statistical (TSS) method. Results showed that the ensemble model achieved the highest Area Under the Curve (AUC) scores (0.99). For B. africanus, precipitation-related variables contributed to determining the suitability for schistosomiasis. Temperature and precipitation-related variables influenced the distribution of B. globosus in all three models. Biomphalaria pfeifferi showed that Temperature Seasonality (bio4) contributed the most (47%) in all three models. According to the models, suitable areas for transmitting schistosomiasis were in the eastern regions of South Africa. Temperature and rainfall can impact the transmission and distribution of schistosomiasis in SA. The results will enable us to develop future projections for Schistosoma in SA based on climate scenarios.


Asunto(s)
Biomphalaria , Esquistosomiasis , Animales , Sudáfrica/epidemiología , Esquistosomiasis/epidemiología , Caracoles , Bulinus , Ecosistema
18.
PLoS One ; 18(10): e0292943, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37856526

RESUMEN

Urogenital schistosomiasis (UGS) caused by Schistosoma haematobium is endemic in the South West Region of Cameroon. An understanding of the abundance and distribution of the Bulinus snail, intermediate host can inform strategic snail control programmes at a local scale. This study investigated seasonal dynamics and environmental factors influencing occurrence and abundance of freshwater snail intermediate hosts in Tiko, a semi-urban endemic focus in the Mount Cameroon area. A longitudinal malacological field survey was conducted between December 2019 and December 2020 in the Tiko municipality. Snails were collected for one year monthly at 12 different human water contact sites along a stretch of the Ndongo stream using a standardized sampling technique. Freshwater snails were identified using shell morphological features. In addition, water temperature, pH, electrical conductivity, total dissolved solutes, salinity, water depth, width and flow velocity were measured, and vegetation cover as well as substrate type were determined. Bayesian regression models were used to identify the main environmental factors affecting the occurrence and abundance of Bulinus intermediate host. In total, 2129 fresh water snails were collected during the study period. Physa (51.4%) was the most abundant genus followed by Melanoides (28.6%) then, Bulinus (15.5%), Lymnaea (4.2%), Indoplanorbis (0.2%) and Potadoma (0.1%). Seasonality in abundance was significant in Bulinus sp as well as other genera, with greater numbers in the dry season (peaks between December and February). Water temperature, a rocky or sandy substrate type associated positively with Bulinus sp, meanwhile a higher water flow rate and medium vegetation negatively influenced the snail intermediate host population. These findings underscore the importance of timing behavioural and snail control interventions against schistosomiasis as well as increase vigilance of other trematode diseases in the study area. The continuous spread of planorbid snail hosts is a major concern.


Asunto(s)
Bulinus , Esquistosomiasis Urinaria , Animales , Humanos , Schistosoma haematobium , Estaciones del Año , Camerún/epidemiología , Teorema de Bayes , Caracoles , Esquistosomiasis Urinaria/epidemiología , Agua Dulce , Agua , Ecosistema
19.
PLoS Negl Trop Dis ; 17(7): e0011487, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37459286

RESUMEN

BACKGROUND: Schistosomiasis and hookworm infection remain public health problems in large parts of sub-Saharan Africa. The epidemiology of schistosomiasis and hookworm was studied in seasonal transmission settings in the northern part of Côte d'Ivoire. METHODOLOGY: In August 2018, a cross-sectional study was conducted. Urine and stool samples were collected from 742 individuals aged 6-96 years in 16 localities from four departments in northern Côte d'Ivoire. Urine samples were examined by a filtration method for quantification of Schistosoma haematobium eggs. Stool samples were subjected to duplicate Kato-Katz thick smears and eggs of Schistosoma mansoni and soil-transmitted helminths (STHs) were counted. Additionally, a questionnaire was administered to determine demographic characteristics and to identify risk factors of schistosomiasis and STHs. Malacologic surveys were carried out at water points that are contacted by humans and animals. PRINCIPAL FINDINGS: The prevalence of schistosomiasis was very low. Only two cases of S. mansoni were found (0.3%, 95% confidence interval [CI]: 0.1-1.0%). The distribution of S. haematobium was focal, with cases found only in two departments; Ferkessédougou (5.4%, 95% CI: 2.5-9.9%) and Ouangolodougou (2.7%, 95% CI: 0.9-6.3%). Hookworm was the only STH species observed with a prevalence of 1.5% (95% CI: 0.8-2.8%). A higher risk of S. haematobium infection was observed in males compared to females, but the difference was not statistically significant (2.3% versus 1.3%, odds ratio [OR]: 1.5, 95% CI: 0.8-2.7). Participants aged 16-20 years showed the highest prevalence of S. haematobium. A total of 111 human- and animal-water contact points were identified at 47 water sources. Three potential intermediate host snails of schistosomes were collected; namely, Bulinus forskalii (n = 761), Bulinus truncatus (n = 205), and Biomphalaria pfeifferi (n = 1). Yet, only one specimen of Bu. truncatus was found to be shedding schistosome cercariae. CONCLUSIONS/SIGNIFICANCE: This study confirms very low transmission of schistosomiasis and hookworm in northern Côte d'Ivoire. The establishment and rigorous implementation of integrated surveillance-response systems could lead to the elimination of schistosomiasis and hookworm in this part of Côte d'Ivoire.


Asunto(s)
Infecciones por Uncinaria , Esquistosomiasis mansoni , Esquistosomiasis , Masculino , Femenino , Animales , Humanos , Estudios Transversales , Côte d'Ivoire/epidemiología , Prevalencia , Estaciones del Año , Esquistosomiasis/epidemiología , Schistosoma haematobium/fisiología , Bulinus , Infecciones por Uncinaria/epidemiología , Suelo/parasitología , Factores de Riesgo , Agua , Esquistosomiasis mansoni/epidemiología , Esquistosomiasis mansoni/parasitología , Heces/parasitología
20.
Environ Sci Pollut Res Int ; 30(32): 78641-78652, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37273057

RESUMEN

Bulinus truncatus snail is one of the most medically important snails. The goal of this study was to evaluate the molluscicidal effect of saponin on these snails and study how it affects their biological functions. The present results showed that saponin had a molluscicidal activity against adult B. truncatus snails after 24h and 72h with LC50 (57.5 and 27.1 ppm, respectively) and had ovicidal acivity on the snails' embryos. By studying the effect of the sublethal concentrations (LC10 48.63 ppm or LC25 52.83 ppm) exposure on B. truncatus snails, they resulted in significant decreases in the survivorship, egg-laying, and the reproductive rate compared to untreated snails. Both concentrations caused morphological changes to the snails' hemocytes, where, after the exposure, granulocytes and hyalinocytes had irregular outer cell membrane and some cell formed pseudopodia. Granulocytes had large number of granules, vacuoles, while hyalinocytes' nucleus was shrunken. Also, these concentrations resulted in significant increases in sex hormone levels (17ß-estradiol and testosterone) in tissue homogenate of B. truncatus snails. It resulted in significant decrease in total antioxidant (TAO) activity, while, significantly increased lipid peroxidase (LPO) level, superoxide dismutase (SOD), nitrogen oxide (NO), and glutathione-S-transferase (GST) as compared to control group. Histopathological and genotoxicological damages occurred in snails' tissue after exposure to these concentrations. Conclusion, saponin has a molluscicidal effect on B. truncatus snails and might be used for the control of schistosomiasis haematobium. Besides, these snails could be used as invertebrate models to reflect the toxic effects of saponin in the aquatic ecosystem.


Asunto(s)
Moluscocidas , Saponinas , Animales , Bulinus , Saponinas/farmacología , Ecosistema , Caracoles , Moluscocidas/toxicidad , Estrés Oxidativo
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