The present study describes the action of the latex of Euphorbia splendens var. hislopii (E. milli) on species of the genus Bulinus and on Biomphalaria pfeifferi, intermediate hosts of schistosomiasis in Africa, and the Brazilian snails B. glabrata, B. tenagophila, and B. straminea, intermediate hosts of schistosomiasis in Brazil. The impact of the latex on the egg masses and embryos of B. glabrata was also evaluated. Using the standardized methodology of the World Health Organization for testing plant-derived molluscicides, we obtained a 90% lethal dose (LD 90) ranging from 0.13 ppm for B. glabrata subjected to lyophilized latex to 4.0 ppm for B. pfeifferi tested with the natural latex. This material has proved to be one of the most potent and specific plant molluscicides discovered thus far, presenting advantages in terms of application so that it could be used in programs involving community participation in endemic areas in both Brazil and Africa.
Biomphalaria glabrata is the main intermediate host involved in schistosomiasis in Brazil. Studies have shown that physiological stress conditions, such as infection with Schistosoma mansoni, starvation, aestivation and exposure to molluscicides, can alter its carbohydrate metabolism (Schwartz & Carter 1982, Becker 1983, Bezerra et al. 1999, Alcanfor 2001, Mello-Silva et al. 2006a). These changes can alter the glycogenesis, gluconeogenesis and glycolysis in the snail.One of most promising Brazilian molluscicides is the crude extract of Euphorbia splendens (Sin. Euphorbia milii), which under laboratory and field conditions meets the recommendations of the WHO for use as a natural molluscicide (Vasconcellos & Amorim 2003). Mello-Silva et al. (2006a, 2007 studied the influence of sublethal doses of the latex of this plant on the carbohydrate and protein metabolism and reproductive biology of B. glabrata and found strong metabolic changes leading to a reduction in its population and consequently in the transmission of the parasite. In spite of this potential, there are no studies of the influence of this product on the physiology of Biomphalaria infected with S. mansoni.The present paper examines the action of the latex of E. splendens var. hislopii on the glucose content of the haemolymph and on the carbohydrate (glycogen) deposits of B. glabrata (BH strain) infected with S. mansoni (BH strain). MATERIALS AND METHODSObtaining the latex of E. splendens var. hislopiiSamples of E. splendens var. hislopii latex were collected in the autumn from plants cultivated in plots near the Biology Department, Fiocruz, in Rio de Janeiro, Brazil. The latex was collected as described by Vasconcellos and Amorim (2003) on the same day the tests were conducted.Lethal dose experiment -Using the recently collected latex, an aqueous stock solution at a concentration of 100 mg/L was prepared and, from this, solutions of different concentrations were prepared for use in the bioassays. The lethal (LC 90 ) and sublethal (LC 50 ) concentrations were determined according to Vasconcellos and Amorim (2003), as recommended by the World Health Organization (1983) and Mott (1987). The LC 50 and LC 90 values were, respectively, 1.0 mg/L and 2.3 mg/L (Mello-Silva et al. 2006a).Balloon flasks (1000 mL) were used and the latex solution was divided into two 500 mL glass beakers. The groups of B. glabrata (BH lineage), infected and uninfected, respectively, were placed in LC 50 solutions and exposed for 24 h (Vasconcellos & Amorim 2003) at 21ºC. Two glass beakers received 500 mL of distilled water without latex as a control group. None of the snails was fed during this period.After the latex exposure period, the snails were removed from the flasks and rinsed in distilled water to remove the residues. The number of dead specimens was noted. (1990). The snails were grouped according to their infection stage (1 day and 1, 2, 3 and 4 weeks post exposure). In each period analysed, 100 infected and 20 uninfected snails (control) were used. Sixty infected sn...
Under laboratory conditions, latex from Euphorbia splendens has shown promise as a plant molluscicide for control of Biomphalaria species, intermediate hosts for Schistosoma mansoni. The purpose of this study was to evaluate its efficiency under field conditions. Application of filtered latex at 12 ppm to one stream in an endemic rural area in Minas Gerais state, Brazil, in September 1995, did result in a reduction in snail density as compared to an untreated stream but the snail population recovered quickly. However, two applications with a two-week interval of unfiltered E. splendens latex at 5 ppm in November 1996 in the same stream resulted in complete disappearance of B. glabrata and snails did not reappear until the 14th month after the applications. In the control stream, without treatment, the snails were found during all months. Laboratory studies confirmed that unfiltered latex is a more potent molluscicide than filtered latex. Considering the advantages of the latex such as its low toxicity to other aquatic animals and its photobiodegradability, as well as the simple method of application, this natural product is promising as an effective molluscicide.
RESUMOFoi estudada a ocorrência de parasitas gastrointestinais em cães recolhidos e mantidos em instituto público de medicina veterinária no Rio de Janeiro, RJ. ABSTRACTThe occurrence of intestinal parasitic helminths in dogs from a public institute of veterinary medicine in Rio de Janeiro was assessed. Samples of fresh feces were collected in March 2004 and analyzed by Willis and centrifugal-flotation in sucrose solution methods. Of 204 samples, 45.6% were positive for helminths.
Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscicidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscicidal effect. The molluscicidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12ºC (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis
ResumoRegistrou-se no município de Resende, Estado do Rio de Janeiro, Brasil, a primeira ocorrência do molusco Achatina fulica hospedeiro intermediário de Angiostrongylus cantonensis, causador da angiostrongilíase meningoencefálica. Em cinco bairros visitados, foram encontrados moluscos vivendo livremente, e nenhum dos animais coletados apresentava a forma larvar do parasito. A presença de A. fulica pode estar relacionada à comercialização desse molusco como alimento, e representa possibilidade de instalação dessa zoonose na região. (Chen, 1935), nematódeo parasita que causa a meningite eosinofílica ou angiostrongilíase meningoencefálica no homem. 4 A manutenção dessa zoonose tem potencial importância na medicina veterinária por apresentar também roedores urbanos e silvestres como hospedeiros definitivos. Abstract O molusco Achatina fulica é o hospedeiro intermediário de Angiostrongylus cantonensis 2Essa espécie, conhecida como caramujo gigante africano, alcança dimensões consideráveis, em torno de 20 cm de comprimento de concha. É um gastrópodo pulmonado terrestre, e sua ampla distribuição geográfica tem sido registrada em diversas regiões da África, Sudeste Asiático (Tailândia, China), Ilhas do Pacífico, Austrália, Japão, e, recentemente, foram registrados casos isolados no continente americano. 5A. fulica é considerado uma praga agrícola por promover grandes prejuízos a lavouras e plantações comerciais. Invade hortas em áreas domiciliares -seu habitat mais comum -, sendo também encontrado em árvores, sobre material em decomposição e próximo a depósitos de lixo.A infecção da angiostrogilíase ocorre após o hospedeiro definitivo ingerir as larvas de terceiro es-
Molluscides have been used as one of the strategies to control schistosomiasis. Many plant extracts with molluscidal effects have been tested, but the action of the latex of Euphorbia splendens var. hislopii is considered the most promising because it meets the recommendations of the World Health Organization (WHO). The objective of this study was to determine the lethal dose and identify the effects of the different doses of latex of E. splendens var.hislopii on the physiology of Biomphalaria glabrata submitted to treatment for 24 h. The concentrations of glucose, uric acid and total proteins in the hemolymph and of glycogen in the digestive gland and cephalopodal mass were determined. The LD 50 value was 1 mg/l. The highest escape index was found to be at a concentration of 0.6 mg/l. The results showed that the latex of E. splendens var. hislopii caused a sharp reduction in the reserves of glycogen in the digestive gland and elevation of the protein content in the hemolymph of B. glabrata. Key words: plant molluscide -Euphorbia splendens var. hislopii -Biomphalaria glabrataThe use of molluscides as one of the strategies to control schistosomiasis began in Brazil in 1976, with the creation of the Special Schistosomiasis Control Program by the National Health Foundation (Machado 1982). The product used in the program was niclosamide, an ethanolamine salt of 2',5-dichloro-4'-nitrosalicylanilide, manufactured under the trade name Bayluscide , whose efficacy had previously been established (Gonnert 1961). Application of this product caused biocidal action on non-target plants and animals (Andrews et al. 1983), besides causing genotoxicity and carcinogenic effects (Vega et al. 1988). The high cost (Pieri 1995), the possibility of recolonization of breeding grounds (Sarquis et al. 1997(Sarquis et al. , 1998, and the ecological toxicity of this product were limitations on its use as an official molluscide in government programs to control schistosomiasis.At the same time, various plants were tested as natural molluscides. Jurberg et al. (1989) (Mendes et al. 1984). Of these, E. splendens stands out for its molluscidal activity in doses under 0.5 mg/l, eight times smaller than the lethal dose for fish (Vasconcellos & Schall 1986).Some questions have arisen in the selection of plant molluscides, such as: toxicity, availability, annual growth, adaptability to different local conditions, and location of molluscidal activity in parts of the plant that easily regenerate, such as the leaves. To be eligible for use, a product must be storable and remain viable for at least one year; be physically and chemically stable; have ethnobotanical value; and be easy to extract and apply, preferably in aqueous extracts (Kloos & McCullough 1982). Considering all these criteria, in 1998 the Oswaldo Cruz Institute (IOC, Fiocruz, RJ) obtained a biotechnology patent on a method to collect, extract and apply E. splendens var. hislopii latex as a molluscide (Vasconcellos 2000).In the published works on plants with molluscidal action and ...
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