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1.
Acta Trop ; 225: 106226, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34752781

RESUMO

Vectors and intermediate hosts of globally impactful human parasites are sensitive to changes in the ecological communities in which they are embedded. Sites of endemic transmission of human schistosome can also be invaded by nonnative species, especially aquatic plants (macrophytes). We tested the effects on macrophyte invasions on experiment snail and schistosome populations created in 100 L mesocosm tanks. We established macrophyte-free mesocosms and those containing one of four widespread macrophyte species that are inedible to snails (duckweed, hornwort, water lettuce, or water hyacinth) and then tracked edible resources (periphyton algae) and the abundance, reproduction, and infection of snail intermediate hosts for 16 weeks. We predicted that the three floating macrophytes would reduce periphyton, thereby reducing snail reproduction, abundance, and infections. In contrast, we predicted that hornwort, which is submerged and provides substrate for periphyton growth, would increase snail reproduction and abundance. As predicted, all floating macrophytes decreased periphyton, but only water hyacinth significantly decreased snail reproduction and abundance. Snail abundance increased significantly only with water lettuce. We hypothesize that this unanticipated increase in snails occurred because water lettuce produced abundant and/or high quality detritus, subsidizing snails despite low periphyton availability. Unfortunately, we detected too few infections to analyze. Aquatic macrophytes exert strong species-specific effects on snail populations. Therefore, efforts to manage invasive plants in endemic sites should evaluate changes in resources, snails, and transmission potential. We recommend caution with management efforts that produce large amounts of detritus, which might stimulate snail populations and therefore risk of human exposure.


Assuntos
Biomphalaria , Plantas , Schistosoma mansoni , Animais , Biomphalaria/crescimento & desenvolvimento , Biomphalaria/parasitologia , Espécies Introduzidas , Dinâmica Populacional
2.
J Helminthol ; 95: e66, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34784987

RESUMO

Host-parasite coevolution may result in life-history changes in hosts that can limit the detrimental effects of parasitism. Fecundity compensation is one such life-history response, occurring when hosts increase their current reproductive output to make up for expected losses in future reproduction due to parasitic infection. However, the potential trade-offs between this increase in quantity and the quality of offspring have been relatively unexplored. This study uses the trematode, Schistosoma mansoni, and its snail intermediate host, Biomphalaria glabrata, to better understand how this host life-history response, fecundity compensation, impacts host reproduction. Measures of host reproductive output as well as offspring hatching success and survival were collected to assess the reproductive consequences of infection. Infected snails exhibited fecundity compensation by increasing the number of eggs laid and the overall probability of laying eggs compared to uninfected snails. Parental infection status did not play a significant role in hatching or offspring survival to maturity. Offspring from a later reproductive bout demonstrated a higher hatching success rate. Overall, the lack of an apparent trade-off between quantity and quality of offspring suggests that infected parental snails invest more resources towards reproduction not only to increase reproductive output, but also to maintain the fitness of their offspring, possibly at the expense of their own longevity.


Assuntos
Biomphalaria , Animais , Fertilidade , Interações Hospedeiro-Parasita , Reprodução , Schistosoma mansoni , Caramujos
3.
Front Cell Infect Microbiol ; 11: 744352, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34621694

RESUMO

Background: Schistosomiasis is one of the most important tropical parasitic diseases worldwide. Biomphalaria straminea, the intermediate host of Schistosoma mansoni, has invaded and spread to Southern China since 1974 and may pose enormous threats to public health. Controlling intermediate host snails is an effective strategy in schistosomiasis intervention. However, the only effective chemical molluscicide, niclosamide, currently recommended by WHO may cause environmental pollution, loss of biodiversity, and high costs. Thus, to counter intermediate hosts, a sustainable and environmentally friendly tool is urgently needed. Here, we conducted field investigations to collect and identify a potential snail competitor rotifer and evaluated its molluscicide effect. Results: In this study, we collected two samples of rotifers from Shenzhen. We found both red and black phenotypic B. straminea snails at the sampling sites. We identified the rotifer population as a species of the genus Philodina according to the amplification and phylogenetic analysis results of coxI gene. We found that rotifer exposure did not significantly affect the hatching rate of B. straminea eggs but promoted the killing of juvenile snails. Meanwhile, rotifer exposure did not significantly alter the fecundity of B. straminea quantified by the number of eggs per egg mass, the number of egg masses per snail, and the number of eggs per snail; but the snails exposed to rotifers showed lower fecundity performance than the control snails. Importantly, rotifer exposure could significantly affect the development of juvenile B. straminea, showing a smaller shell diameter of the exposed snails than that of the control snails. In addition, rotifer exposure affected the life span of B. straminea snails, showing a 16.61% decline in the average life span. After rotifer exposure, the S. mansoni-infected B. straminea snails died significantly faster than those without rotifer exposure. Similar findings were observed in S. mansoni-infected Biomphalaria glabrata snails. These results implied that rotifer exposure significantly promoted the mortality of S. mansoni-infected B. straminea and B. glabrata. Conclusions: Our study demonstrated the potential molluscicide effect of rotifers on intermediate hosts under laboratory conditions. Our findings may provide new insights into the development of biocontrol strategies for snail-borne disease transmission.


Assuntos
Biomphalaria , Esquistossomose mansoni , Animais , China , Filogenia , Schistosoma mansoni/genética
4.
Parasitol Res ; 120(12): 4023-4035, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34657981

RESUMO

Biomphalaria spp. snails are intermediary hosts of Schistosoma mansoni, etiologic agent of intestinal schistosomiasis, one of the most important neglected tropical diseases. Biomphalaria straminea is an important intermediary host that possess a different phenotype to parasite infection but shows a large geographic distribution and high capacity of new ecologic niche invasion. Our purpose was to characterize for the first time the differentially expressed proteome in B. straminea during two times intervals after primary and secondary exposure to S. mansoni. The hemolymph was collected at 1 and 15 days after primary and secondary exposure of snails to the parasite. Total proteins were extracted and digested with trypsin. LC-MS/MS label-free quantification was performed and analyzed using Maxquant and Perseus software. Proteins were identified and annotated using Blast2GO tools. After 1 day of exposure, most of upregulated proteins are hemoglobin type 2, C and H type lectins, molecules related to cell adhesion, and response to oxidative stress. After 15 days, we found a similar pattern of upregulated proteins but some fibrinogen-related proteins (FREPs) and TEPs homologs were downregulated. Regarding the differentially expressed proteins during secondary response, the principal immune-related proteins upregulated were C and H type lectins, cellular adhesion molecules, biomphalysin, and FREP3. We noted a several upregulated biological processes during both responses that could be the one of the key points of efficacy in the immune response to parasite. Our data suggests different immune mechanisms used by B. straminea snails challenged with S. mansoni.


Assuntos
Biomphalaria , Esquistossomose mansoni , Animais , Cromatografia Líquida , Memória Imunológica , Proteômica , Schistosoma mansoni , Espectrometria de Massas em Tandem
5.
Acta Trop ; 224: 106132, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34509457

RESUMO

The present study identified locations with the presence of Biomphalaria and the areas at risk for Schistosoma mansoni, the etiological agent of schistosomiasis, in the Metropolitan Region of São Paulo (MRSP), located in the Alto Tietê Basin (ATB), São Paulo, Brazil. The study area comprises floodplains of the Tietê River from its source, in Salesópolis, to Rasgão Dam, in Pirapora do Bom Jesus, covering 39 municipalities. Data from the planorbidic chart of the malacology laboratory of the Endemic Control Superintendence for 2008-2016 were used, as well as data from the notification forms of cases of human schistosomiasis in 2006-2015 made available by the Epidemiological Surveillance Groups of Mogi das Cruzes and Osasco, and by the Health and Surveillance Coordination of São Paulo. These data were used to generate maps of the distribution of Biomphalaria, of the scanning analysis, of the Gi statistics of the autochthonous and imported schistosomiasis cases, and of the flow of cases imported from other Brazilian states and municipalities in the state of São Paulo to the study area. A total of 21,618 specimens of the genus Biomphalaria were captured and six species were identified. Biomphalaria tenagophila was the predominant species in the region and of greatest epidemiological importance as it is the main responsible for the transmission of the disease in the state of São Paulo. A total of 3,623 cases of schistosomiasis were reported in the study area, and São Paulo and Guarulhos were the municipalities with the highest number of autochthonous and imported cases during the study period. The imported cases originated from 21 Brazilian states plus the Federal District and from 51 municipalities in São Paulo state located outside the study area. Autochthonous clusters with high risk for the occurrence of schistosomiasis were identified in the municipalities of São Paulo, Guarulhos, Santa Isabel/Mogi das Cruzes/Arujá, and Cotia/Itapevi. Clusters of imported cases were also identified in Itaquaquecetuba, at the border of Cotia/Itapevi and Suzano/São Paulo/Mogi das Cruzes. The presence of B. tenagophila in the ATB and in the clusters of autochthonous cases herein identified, although not carrying schistosome larvae, represents a risk for the transmission of infectious agents. The human population in the MRSP mainly occupies the lowlands of the Tietê River, which are locations with poor coverage of basic sanitation. Therefore, measures for the control and surveillance of schistosomiasis such as educational actions, improvements in basic sanitation, and the malacological and epidemiological monitoring of these areas are extremely important.


Assuntos
Biomphalaria , Esquistossomose mansoni , Esquistossomose , Animais , Brasil/epidemiologia , Humanos , Schistosoma mansoni , Esquistossomose/epidemiologia , Esquistossomose mansoni/epidemiologia , Análise Espacial
6.
Acta Trop ; 223: 106089, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34389324

RESUMO

The molluscicidal action of essential oils have been attributed to the most prevalent terpene compounds. However, molluscicidal properties, mode of action, and toxicity to non-target organisms remain unclear. In this study, the molluscicidal potential of four monoterpenes (camphor, thymol, α-pinene, and 1,8-cineole) against the snail Biomphalaria glabrata, an intermediate host of Schistosoma mansoni, was analyzed. The molluscicide activity of each monoterpene was assessed by the standardized test of the World Health Organization (WHO) and the monoterpenes considered active against B. glabrata were analyzed as inhibitors of the enzymatic activity of acetylcholinesterase (AChE) extracted from snails. In addition, acute toxicity to non-target organisms was assessed against Danio rerio fish. The results show that camphor and 1,8-cineole monoterpenes did not induce snail mortality. Thymol and α-pinene were active against B. glabrata, inducing mortality in concentration-dependent patterns and showing a lethal effect in concentrations compatible with that recommended by the WHO (LC90 of 7.11 and LC90 10.34 µg ∙ mL-1, respectively). The toxic action of thymol and α-pinene on snails indicates that these monoterpenes may account for or largely contribute to the molluscicidal activity of essential oils that contain them as major compounds. Thymol and α-pinene inhibit the AChE of B. glabrata at concentrations higher than those used in the molluscicide test. These monoterpenes show low toxicity to non-target organisms compared to the commercial molluscicide niclosamide. Knowledge about monoterpene toxicity against B. glabrata contributes to its potential use in molluscicidal formulations and in alternatives to the control of snails that host intermediate S. mansoni, a crucial action in the prevention and transmission of schistosomiasis, a neglected tropical disease.


Assuntos
Biomphalaria , Inibidores da Colinesterase/farmacologia , Moluscocidas , Monoterpenos , Acetilcolinesterase , Animais , Biomphalaria/efeitos dos fármacos , Biomphalaria/enzimologia , Moluscocidas/farmacologia , Monoterpenos/farmacologia , Schistosoma mansoni
7.
Parasit Vectors ; 14(1): 388, 2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34362440

RESUMO

BACKGROUND: Schistosomiasis a neglected tropical disease  endemic in Brazil. It is caused by the trematode Schistosoma mansoni, which is transmitted by snails of the genus Biomphalaria. Among measures used to control and eliminate schistosomiasis, accurate mapping and monitoring of snail breeding sites are recommended. Despite the limitations of parasitological methods, they are still used to identify infected snails. Loop-mediated isothermal amplification (LAMP) is a sensitive, rapid, and cost-effective diagnostic method for the identification of infected snails. In the work reported here, we aimed to validate the use of LAMP for the detection of S. mansoni in snails of the genus Biomphalaria. METHODS: Snails were collected in five municipalities of the Mucuri Valley and Jequitinhonha Valley regions in the state of Minas Gerais, Brazil. Snails were pooled according to collection site and then squeezed for the detection of S. mansoni and other trematode larvae. Pooled snails were subjected to pepsin digestion and DNA extraction. Molecular assays were performed for species-specific identification and characterization of the samples. A previously described LAMP assay was adapted, evaluated, and validated using laboratory and field samples. RESULTS: Using the parasitological method described here, S. mansoni cercariae were detected in snails from two collection sites, and cercariae of the family Spirorchiidae were found in snails from one site. The snails were identified by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Biomphalaria glabrata, the main snail host of S. mansoni in Brazil, was detected in 72.2% of the collection sites. Biomphalaria kuhniana, which is resistant to S. mansoni infection, was found in the remaining sites. Multiplex, low stringency (LS), and conventional PCR allowed the detection of positive snails in four additional sites. Trematodes belonging to the families Strigeidae and Echinostomatidae were detected by multiplex PCR in two sites. The LAMP assay was effective in detecting the presence of S. mansoni infection in laboratory (7 days post-infection) and field samples with no cross-reactivity for other trematodes. When compared to LS and conventional PCR, LAMP showed 100% specificity, 85.7% sensitivity, and a κ index of 0.88. CONCLUSIONS: Our findings suggest that LAMP is a good alternative method for the detection and monitoring of transmission foci of S. mansoni, as it was three times as effective as the parasitological examination used here for the detection of infection, and is more directly applicable in the field than other molecular techniques.


Assuntos
Biomphalaria/parasitologia , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Schistosoma mansoni/genética , Animais , Brasil , Doenças Endêmicas , Esquistossomose mansoni/epidemiologia , Especificidade da Espécie
8.
Acta Trop ; 223: 106102, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34416188

RESUMO

This research investigated the effect of the Croton rudolphianus leaf essential oil (EO) on Biomphalaria glabrata embryos (at different development stages) and adults, Schistosoma mansoni cercariae, and Artemia salina (non-target organism). It was possible to identify 31 compounds in the C. rudolphianus EO through GC-MS analysis. The major compounds from this oil were (E)-caryophyllene (17.33%), an unknown compound (16.87%), bicyclogermacrene (7.1%), δ-cadinene (6.62%) and germacrene D (5.38%). After incubation for 24 h, the EO of C. rudolphianus induced the occurrence of non-viable embryos (dead and malformed), with an LC50 value of 126.54, 133.51, 143.53 and 161.95 µg/mL and an LC90 value of 202.61, 216.48, 232.98 and 271.16 µg/mL to blastula, gastrula, trochophore and veliger embryonic stages, respectively. The EO was more effective against B. glabrata adults (LC50 and LC90 = 47.89 and 78.86 µg/mL, respectively), and S. mansoni cercariae (LC50 and LC90 = 14.81 and 22.15 after 120 mins of exposure, respectively) than against B. glabrata embryos. Concerning the micronucleus assay, the mean frequency of apoptosis, binucleation and micronucleus were 45.33 ± 3.51, 19.33 ± 1.53 and 0.67 ± 0.58 per 1000 cells at 25 µg/mL, which is the highest concentration tested. The oil killed A. salina with LC50 and LC90 values (68.33 and 111.5 µg/mL, respectively) higher than those determined for adult snails and S. mansoni cercariae. In conclusion, C. rudolphianus EO had a toxic effect against B. glabrata adults and embryos, and S. mansoni cercariae. Furthermore, this oil showed to be cytotoxic to hemocytes of B. glabrata. Concerning the non-target organism assay, C. rudolphianus EO was less toxic to A. salina then to adult snails and S. mansoni cercariae. Due to this, the EO from C. rudolphianus leaves is a potential alternative for schistosomiasis control.


Assuntos
Biomphalaria , Óleo de Cróton/farmacologia , Croton , Moluscocidas , Óleos Voláteis , Schistosoma mansoni/efeitos dos fármacos , Animais , Artemia/efeitos dos fármacos , Biomphalaria/efeitos dos fármacos , Croton/química , Óleos Voláteis/farmacologia , Folhas de Planta/química
9.
Acta Trop ; 222: 106067, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34303689

RESUMO

Schistosomiasis is a public health problem in many developing countries. The mollusc Biomphalaria glabrata is the most important vector of Schistosoma mansoni in South America. The population control of this vector to prevent the spread of schistosomiasis is currently done with the application of highly toxic molluscicide to the environment. The screening of substances in sublethal concentrations that have deleterious effects on physiological parameters is very relevant for the control of schistosomiasis, since the effectiveness of disease prevention increases if it acts on population control of the vector and on reproduction and elimination in S. mansoni cercariae. The objective of this study was to evaluate the reproductive parameters (fecundity and fertility), intra-mollusk effect (sporocysts I (72 h) and II (14 days after)) on the development of cercariae of S. mansoni and the immune cell profile of B. glabrata exposed to sublethal concentrations (LC25 - 0.5 µg/mL and LC50 - 0.92 µg/mL) of the usnic acid potassium salt (potassium usnate). LC 25 and LC 50 significantly reduced (p < 0.05) the fecundity of B. glabrata when treated infected and/or not exposed to infection, while unviable embryos were not observed in sporocyst stage I, being only significant (p < 0.05) for mollusks infected and treated with LC50 on sporocyst II. LC25 and LC50 of the potassium usnate caused significant reductions (p < 0.05) in the production and cercarial shedding when evaluated on sporocysts I and II. In addition, the mortality of infected and treated B. glabrata in the sporocyst II phase was quite marked after the 9th week of infection. Regarding the immunological cell profile of uninfected B. glabrata, both concentrations led to immunomodulatory responses, with significant morphological changes predominant of hemocytes that entered programmed cell death (apoptosis). It was concluded that the application of LC25 and LC50 from the potassium usnate could be useful in the population control of B. glabrata, since it interferes both in their biology and physiology and in the reproduction of the infectious agent of schistosomiasis mansoni.


Assuntos
Benzofuranos/farmacologia , Biomphalaria , Animais , Biomphalaria/efeitos dos fármacos , Biomphalaria/parasitologia , Potássio , Schistosoma mansoni
10.
An Acad Bras Cienc ; 93(2): e20190691, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34076034

RESUMO

Our main objective was to perform a preliminary survey of the non-marine gastropods at the Estação Biológica Fiocruz Mata Atlântica (EFMA) and its adjacent urban areas, also considering samples from other localities of the Parque Estadual da Pedra Branca received as donation, in Rio de Janeiro, RJ, Brazil. Infection by larval helminths of medical and veterinary importance was also investigated in 348 specimens of five freshwater species and two specimens of the terrestrial species Achatina fulica. In all, 584 samples of molluscs from 34 collection sites were obtained. They represented 31 species classified in 16 families. Fifteen species were exclusive to the EFMA area. In the urban area mainly exotic and/or synanthropic species were found. Some of them were found in the forest border as well. The freshwater Biomphalaria tenagophila, an intermediate host of the trematode that causes schistosomiasis mansoni, was found parasitized by Xiphidiocercarie cercariae and the Afro-asiatic Melanoides tuberculata by Pleurolophocercus cercaria. The finding of endemic and exotic species, including transmitters of parasites, demonstrate the importance of fast surveys such as the present study. However, considering the great diversity of endemic molluscs found in a relatively small part of the EFMA, we highlight the necessity of further additional studies.


Assuntos
Biomphalaria , Animais , Brasil , Florestas , Água Doce , Humanos , Caramujos
11.
Ecology ; 102(7): e03383, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33950517

RESUMO

Parasites can harm hosts and influence populations, communities, and ecosystems. However, parasites are reciprocally affected by population- and community-level dynamics. Understanding feedbacks between infection dynamics and larger-scale epidemiological and ecological processes could improve predictions and reveal novel control methods. We evaluated how exploitative resource competition among hosts, a fundamental aspect of population biology, influences within-host infection dynamics of the widespread human parasite Schistosoma mansoni in its intermediate host, Biomphalaria glabrata. We added size-dependent consumption of shared resources to a parameterized bioenergetics model to predict a priori the growth, parasite production, and survival of an infected focal host coexisting with an uninfected conspecific competitor in an experiment that varied competitor size. The model quantitatively anticipated that competitors disrupt growth and parasite production and that these effects increase with competitor size. Fitting the model to these data improved its match to host survivorship. Thus, resource competition alters infection dynamics, there are strong size asymmetries in these effects, and size-asymmetric resource competition effects on infection dynamics can be accurately predicted by bioenergetics theory. More broadly, this framework can assess parasite transmission and control in other contexts, such as in resource competitive host communities, or in response to eutrophication, food supplementation, or culling.


Assuntos
Biomphalaria , Parasitos , Animais , Ecossistema , Interações Hospedeiro-Parasita , Humanos , Schistosoma mansoni , Caramujos
12.
Korean J Parasitol ; 59(2): 121-129, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33951767

RESUMO

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.


Assuntos
Biomphalaria/crescimento & desenvolvimento , Bulinus/crescimento & desenvolvimento , Reservatórios de Doenças/estatística & dados numéricos , Rios/parasitologia , Animais , Biomphalaria/parasitologia , Bulinus/parasitologia , Reservatórios de Doenças/parasitologia , Ecossistema , Dinâmica Populacional , Rios/química , Schistosoma/classificação , Schistosoma/genética , Schistosoma/isolamento & purificação , Estações do Ano , Sudão
13.
Int J Parasitol ; 51(11): 935-943, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34044004

RESUMO

Within a single organism, numerous parasites often compete for space and resources. This competition, together with a parasite's ability to locate and successfully establish in a host, can contribute to the distribution and prevalence of parasites. Coinfection with trematodes in snail intermediate hosts is rarely observed in nature, partly due to varying competitive abilities among parasite taxa. Using a freshwater snail host (Biomphalaria glabrata), we studied the ability of a competitively dominant trematode, Echinostoma caproni, to establish and reproduce in a host previously infected with a less competitive trematode species, Schistosoma mansoni. Snails were exposed to S. mansoni and co-exposed to E. caproni either simultaneously or 1 week, 4 weeks, or 6 weeks post S. mansoni exposure. Over the course of infection, we monitored the competitive success of the dominant trematode through infection prevalence, parasite development time, and parasite reproductive output. Infection prevalence of E. caproni did not differ among co-exposed groups or between co-exposed and single exposed groups. However, E. caproni infections in co-exposed hosts took longer to reach maturity when the timing between co-exposures increased. All co-exposed groups had higher E. caproni reproductive output than single exposures. We show that although timing of co-exposure affects the development time of parasite transmission stages, it is not important for successful establishment. Additionally, co-exposure, but not priority effects, increases the reproductive output of the dominant parasite.


Assuntos
Biomphalaria , Echinostoma , Parasitos , Animais , Interações Hospedeiro-Parasita , Reprodução , Schistosoma mansoni
14.
Parasit Vectors ; 14(1): 222, 2021 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-33892778

RESUMO

BACKGROUND: Schsistosomiasis is endemic in sub-Saharan Africa. It is transmitted by intermediate host snails such as Bulinus and Biomphalaria. An understanding of the abundance and distribution of snail vectors is important in designing control strategies. This study describes the spatial and seasonal variation of B. globosus and Bio. pfeifferi and their schistosome infection rates between May 2014 and May 2015 in Ingwavuma, uMkhanyakude district, KwaZulu-Natal province, South Africa. METHODS: Snail sampling was done on 16 sites once every month by two people for 30 min at each site using the scooping and handpicking methods. Snails collected from each site were screened for schistosome mammalian cercariae by the shedding method. The negative binomial generalised linear mixed model (glmm) was used to determine the relationship between abundances of the intermediate host snails and climatic factors [rainfall, land surface temperatures (LST), seasons, habitats, sampling sites and water physico-chemical parameters including pH and dissolved oxygen (DO)]. RESULTS: In total, 1846 schistosomiasis intermediate host snails were collected during the study period. Biompharia pfeifferi was more abundant (53.36%, n = 985) compared to B. globosus (46.64%, n = 861). Bulinus globosus was recorded at 12 sites (75%) and Bio. pfeifferi was present at 7 sites (43.8%). Biompharia pfeifferi cohabited with B. globosus at all the sites it was present. High numbers of Bio. pfeifferi (n = 872, 88.5%) and B. globosus (n = 705, 81.9%) were found between winter and mid-spring. Monthly rainfall showed a statistically significant negative relationship with the abundance of B. globosus (p < 0.05). Dissolved oxygen (DO) had a statistically significant positive relationship with the abundance of Bio. pfeifferi (p < 0.05) while (LST) had a statistically significant negative relationship (p < 0.05). More B. globosus (8.9%, n = 861) were shedding schistosome mammalian cercariae compared to Bio. pfeifferi (0.1%, n = 985) confirming the already documented high prevalence of S. haematobium in Ingwavuma compared to S. mansoni. CONCLUSION: Results of this study provide updated information on the distribution of schistosomiasis intermediate host snails in the study area and contributes towards the understanding of the transmission dynamics of schistosomiasis at the micro-geographical scale in this area.


Assuntos
Biomphalaria , Bulinus , Esquistossomose/transmissão , Animais , Vetores de Doenças , Dinâmica Populacional , Estações do Ano , África do Sul , Análise Espacial
15.
Proc Natl Acad Sci U S A ; 118(11)2021 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-33836584

RESUMO

Temperature constrains the transmission of many pathogens. Interventions that target temperature-sensitive life stages, such as vector control measures that kill intermediate hosts, could shift the thermal optimum of transmission, thereby altering seasonal disease dynamics and rendering interventions less effective at certain times of the year and with global climate change. To test these hypotheses, we integrated an epidemiological model of schistosomiasis with empirically determined temperature-dependent traits of the human parasite Schistosoma mansoni and its intermediate snail host (Biomphalaria spp.). We show that transmission risk peaks at 21.7 °C (T opt ), and simulated interventions targeting snails and free-living parasite larvae increased T opt by up to 1.3 °C because intervention-related mortality overrode thermal constraints on transmission. This T opt shift suggests that snail control is more effective at lower temperatures, and global climate change will increase schistosomiasis risk in regions that move closer to T opt Considering regional transmission phenologies and timing of interventions when local conditions approach T opt will maximize human health outcomes.


Assuntos
Biomphalaria/fisiologia , Biomphalaria/parasitologia , Schistosoma mansoni , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/transmissão , Animais , Interações Hospedeiro-Parasita , Humanos , Temperatura
16.
Front Immunol ; 12: 635131, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33868258

RESUMO

Aerolysins initially characterized as virulence factors in bacteria are increasingly found in massive genome and transcriptome sequencing data from metazoans. Horizontal gene transfer has been demonstrated as the main way of aerolysin-related toxins acquisition in metazoans. However, only few studies have focused on their potential biological functions in such organisms. Herein, we present an extensive characterization of a multigene family encoding aerolysins - named biomphalysin - in Biomphalaria glabrata snail, the intermediate host of the trematode Schistosoma mansoni. Our results highlight that duplication and domestication of an acquired bacterial toxin gene in the snail genome result in the acquisition of a novel and diversified toxin family. Twenty-three biomphalysin genes were identified. All are expressed and exhibited a tissue-specific expression pattern. An in silico structural analysis was performed to highlight the central role played by two distinct domains i) a large lobe involved in the lytic function of these snail toxins which constrained their evolution and ii) a small lobe which is structurally variable between biomphalysin toxins and that matched to various functional domains involved in moiety recognition of targets cells. A functional approach suggests that the repertoire of biomphalysins that bind to pathogens, depends on the type of pathogen encountered. These results underline a neo-and sub-functionalization of the biomphalysin toxins, which have the potential to increase the range of effectors in the snail's immune arsenal.


Assuntos
Biomphalaria/genética , Vetores de Doenças , Evolução Molecular , Família Multigênica , Proteínas Citotóxicas Formadoras de Poros/genética , Schistosoma mansoni/patogenicidade , Animais , Biomphalaria/metabolismo , Biomphalaria/parasitologia , Duplicação Gênica , Variação Genética , Interações Hospedeiro-Parasita , Filogenia , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Especificidade da Espécie
17.
Rev Soc Bras Med Trop ; 54: e0851, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33886822

RESUMO

INTRODUCTION: Ourinhos is a municipality located between the Pardo and Paranapanema rivers, and it has been characterized by the endemic transmission of schistosomiasis since 1952. We used geospatial analysis to identify areas prone to human schistosomiasis infections in Ourinhos. We studied the association between the sewage network, co-occurrence of Biomphalaria snails (identified as intermediate hosts [IHs] of Schistosoma mansoni), and autochthonous cases. METHODS: Gi spatial statistics, Ripley's K12-function, and kernel density estimation were used to evaluate the association between schistosomiasis data reported during 2007-2016 and the occurrence of IHs during 2015-2017. These data were superimposed on the municipality sewage network data. RESULTS: We used 20 points with reported IH; they were colonized predominantly by Biomphalaria glabrata, followed by B. tenagophila and B. straminea. Based on Gi statistics, a significant cluster of autochthonous cases was superimposed on the Christoni and Água da Veada water bodies, with distances of approximately 300 m and 2200 m from the points where B. glabrata and B. straminea were present, respectively. CONCLUSIONS: The residence geographical location of autochthonous cases allied with the spatial analysis of IHs and the coverage of the sewage network provide important information for the detection of human-infection areas. Our results demonstrated that the tools used for direct surveillance, control, and elimination of schistosomiasis are appropriate.


Assuntos
Biomphalaria , Esquistossomose mansoni , Esquistossomose , Animais , Brasil/epidemiologia , Vetores de Doenças , Sistemas de Informação Geográfica , Humanos , Schistosoma mansoni , Esquistossomose/epidemiologia , Esquistossomose mansoni/epidemiologia , Esgotos
18.
Mar Drugs ; 19(5)2021 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-33922065

RESUMO

Schistosomiasis is a parasitic disease that affects more than 250 million people. The treatment is limited to praziquantel and the control of the intermediate host with the highly toxic molluscicidal niclosamide. Marine algae are a poorly explored and promising alternative that can provide lead compounds, and the use of multivariate analysis could contribute to quicker discovery. As part of our search for new natural compounds with which to control schistosomiasis, we screened 45 crude extracts obtained from 37 Brazilian seaweed species for their molluscicidal activity against Biomphalaria glabrata embryos and schistosomicidal activities against Schistosoma mansoni. Two sets of extracts were taxonomically grouped for metabolomic analysis. The extracts were analyzed by GC-MS, and the data were subjected to Pattern Hunter and Pearson correlation tests. Overall, 22 species (60%) showed activity in at least one of the two models. Multivariate analysis pointed towards 3 hits against B. glabrata veliger embryos in the Laurencia/Laurenciella set, 5 hits against B. glabrata blastula embryos, and 31 against S. mansoni in the Ochrophyta set. Preliminary annotations suggested some compounds such as triquinane alcohols, prenylated guaianes, dichotomanes, and xenianes. Despite the putative identification, this work presents potential candidates and can guide future isolation and identification.


Assuntos
Biomphalaria/efeitos dos fármacos , Bioprospecção , Descoberta de Drogas , Moluscocidas/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/prevenção & controle , Esquistossomicidas/farmacologia , Alga Marinha/metabolismo , Animais , Biomphalaria/parasitologia , Brasil , Metaboloma , Metabolômica , Moluscocidas/isolamento & purificação , Schistosoma mansoni/crescimento & desenvolvimento , Esquistossomose mansoni/parasitologia , Esquistossomicidas/isolamento & purificação
19.
J Parasitol ; 107(2): 349-357, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33906231

RESUMO

Schistosoma mansoni, which causes human intestinal schistosomiasis, continues to be a major public health concern in the Lake Victoria basin in western Kenya, with Biomphalaria sudanica (a shoreline inhabiting snail) and Biomphalaria choanomphala (a deep-water snail) playing roles in transmission. A recent study showed that B. sudanica was abundantly present near all study villages on the lakeshore, but B. choanomphala was significantly more abundant near villages known to be persistent transmission hotspots. The present study investigated the relative compatibility of B. sudanica and B. choanomphala with S. mansoni. A reciprocal cross-infection experiment used young adult F1 generation B. sudanica and B. choanomphala that were exposed to either 1, 5, or 10 sympatric or allopatric human-derived S. mansoni miracidia. Three weeks post-exposure (PE) and weekly thereafter, the snails were counted and screened for schistosome cercariae, and at 7 wk PE, total cercariae shed during a 2 hr period by each infected snail was determined. Pre-patent periods for S. mansoni in both B. sudanica and B. choanomphala were similar, and most snails in all exposure combinations started shedding cercariae 5 wk PE. Prevalences were significantly higher in B. choanomphala (12.2-80.9%) than in B. sudanica (5.2-18.6%) at each dose, regardless of whether miracidia were of an allopatric or a sympatric source (P < 0.0001). Overall, the odds of a snail becoming infected with 5 or 10 miracidia were significantly higher than the odds of being infected with 1 miracidium, (P < 0.0001), and fewer cercariae were produced by snails exposed to single as compared to 5 or 10 miracidia. On average, B. choanomphala produced more cercariae ( = 458, SD = 414) than B. sudanica ( = 238, SD = 208) (P < 0.0001). These results suggest that B. choanomphala is more compatible with S. mansoni than B. sudanica. Though B. choanomphala can be found in shallow shoreline waters, it is, for the most part, a deeper-water taxon. Because dredging is a relatively inefficient means of sampling, B. choanomphala is likely underestimated with respect to its population size, the number of S. mansoni-positive snails, and its role in maintaining transmission.


Assuntos
Biomphalaria/fisiologia , Biomphalaria/parasitologia , Vetores de Doenças , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/transmissão , Animais , Biomphalaria/classificação , Biomphalaria/imunologia , Fezes/parasitologia , Humanos , Quênia/epidemiologia , Esquistossomose mansoni/epidemiologia
20.
Parasitol Res ; 120(5): 1909-1914, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33686501

RESUMO

Temporary ponds are ecologically valuable habitats and useful sites for studies of diversity, ecology, evolution, and climate change. Organisms inhabiting these environments have developed strategies to ensure their survival. However, little is known about the temporal dynamics and strategies of parasites in these habitats. A 4-year study was carried out in a temporary pond to analyze the larval digenean assemblage in Biomphalaria peregrina, a potential vector of Schistosoma mansoni, a zoonosis of global importance. This environment had intermittent and irregular hydroperiods, and the overall prevalence showed differences throughout the years. After drought seasons, eight out of a total of nine species of digeneans were observed, and almost half of the snails were parasitized. In addition, six of the nine species of digeneans showed some type of abbreviation of their life cycles. These results suggest that digeneans have certain degree of plasticity in their life cycles in response to environmental changes in this pond, and the abbreviation of the digenean life cycle could be regarded as a parasite strategy to resist prolonged periods of desiccation.


Assuntos
Biomphalaria/parasitologia , Secas , Lagoas , Schistosoma mansoni/isolamento & purificação , Animais , Argentina , Vetores de Doenças , Ecossistema , Larva/parasitologia , Estágios do Ciclo de Vida , Estações do Ano
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