Resumo Helmintos parasitos tem sido estudados como acumuladores potenciais para diferentes poluentes. O trematódeo E. paraensei tem como hospedeiro vertebrado o roedor Nectomys squamipes naturalmente exposto a pesticidas no meio ambiente. No entanto, pouca informação está disponível sobre os efeitos dos pesticidas em helmintos parasitos. O presente estudo investigou, em condições experimentais, os efeitos morfológicos no trematódeo E. paraensei após a exposição ao herbicida Roundup®, em concentrações abaixo das recomendadas para a utilização agrícola. A microscopia eletrônica de varredura (MEV) mostrou após duas horas de exposição, alterações no tegumento, como enrugamento, contração e descamação com perda de espinhos no colar peristômico e análise histopatológica evidenciou células do ceco alteradas, as glândulas vitelínicas com vacúolos e mudanças estruturais nas camadas musculares. Diminuição do conteúdo glicídico, principalmente no tecido conjuntivo, também foi observado. Considerando a predisposição à exposição a pesticidas agrícolas de N. squamipes infectado por E. paraensei, são necessários estudos para avaliar o impacto de tais resíduos frente aos helmintos e seus hospedeiros.

Abstract Helminth parasites have been studied as potential accumulators for different pollutants. Echinostoma paraensei is a foodborne trematode whose vertebrate host, the rodent Nectomys squamipes, is naturally exposed to environmental pesticides. However, little information exists regarding the pesticide’s effects on helminths. This study investigated the morphological effects on the trematode, E. paraensei, after experimental Roundup® herbicide exposure, in concentrations below those recommended for agricultural use. After two hours of exposure, scanning electron microscopy (SEM) showed changes to the tegument, such as furrowing, shrinkage, peeling, spines loss on the peristomic collar, and histopathological evidence of altered cells in the cecum and acinus vitelline glands with vacuoles and structural changes to the muscular layers. Glycidic content was decreased, primarily in the connective tissue. As E. paraensei is an intestinal parasite of the semi-aquatic wild rodent, N. squamipes, it is predisposed to pesticide exposure resulting from agricultural practices. Therefore, we emphasize the need to evaluate its impact on helminth parasites, due to their pivotal role in regulating host populations.

This paper evaluates the alterations in the glycogen content of tissues (digestive gland and cephalopedal mass) and glucose in the haemolymph of Biomphalaria glabrata BH strain infected with Schistosoma mansoni BH strain and exposed to the latex of Euphorbia splendens var. hislopii. A reduction in the glycogen deposits was observed in infected snails exposed and not exposed to latex. However, the exposure to latex caused a greater depletion of the glycogen levels in both sites analysed, especially from the third week onward. The utilisation of latex as a molluscicide to control the population of infected B. glabrata selectively is proposed.

The reproductive activity of Biomphalaria glabrata exposed to Euphorbia splendens var. hislopii latex was evaluated. Parameters related to fecundity and fertility were observed. The snails were exposed to the LD50 (1 mg/l) of crude latex. At the first week post exposure (p.e.), the egg laying was reduced. After the fourth week p.e., an increase of the number of eggs/snail occurred. The results showed a marked reduction in the hatching of the snails, revealing an interference of latex exposure with the reproductive process of B. glabrata of E. splendens var. hislopii. The LD50 of the latex may be used as an alternative method to control the size of the populations of B. glabrata in field.

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 LD50 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.

The aim of this study was to determine the toxicity of niclosamide (Bayluscide ®) on Melanoides tuberculata and Biomphalaria glabrata under laboratory conditions. The latter species is the intermediate host of Schistosoma mansoni (Sambon 1917). M. tuberculata was successfully used as competitor of B. glabrata in biological control programs in French West Indies. Both molluscicide and biological control using M. tuberculata have proved to be successful in reducing the population density of B. glabrata. The associated use of molluscicide in this area would be an effective measure if M. tuberculata were less susceptibility to the molluscicide than B. glabrata. Three hundreds individuals each of B. glabrata and of M. tuberculata, collected in Sumidouro, State of Rio de Janeiro, were used in the experiment. The molluscs were exposed to 14 different concentrations of niclosamide as recommended by the World Health Organization. Probit analysis was used to determine the LC 50 and LC 90. The LC 50 and LC 90 values for B. glabrata were 0.077 mg/l and 0.175 mg/l, respectively and the LC 50 and LC 90 values for M. tuberculata were 0.082 mg/l and 0.221 mg/l respectively. As the lethal concentrations of niclosamide were approximately the same to both species, this could be a disadvantage when controlling B. glabrata with niclosamide in an area of M. tuberculata occurrence. It migth therefore be preferable to utilize the latex extracted from the Euphorbia splendens, which presented a much higher efficiency for B. glabrata than to M. tuberculata.

Observações histológicas em moluscos da espécie Lymnaea columella foram realizadas para determinar a existência ou não de alterações provocadas pelo uso do látex de Euphorbia splendens var. hislopii. O experimento foi realizado de acordo com os métodos padronizados pela OMS. Cinqüenta exemplares de L. columella, com comprimento de concha de 6±1mm, foram submetidos a 200ml das soluções nas concentrações de 0,47µl/L; 0,76µl/L; 0,94µl/L e 1,51µl/L, durante 24 horas. Após o evento experimental, os moluscos foram colocados em solução de Raillet & Henry, para sacrifício e fixação. Os resultados demonstraram lesões caracterizadas por degeneração, necrose e acúmulo de líquido na glândula digestiva e no rim, em exemplares submetidos a concentrações a partir de 0,47 mil/L.

Histological observations in Lymnaea columella snails to determine the existence or not of changes caused by the use of the Euphorbia splendens's latex were realized. The experiment was realized in agreement with the methods standardized by WHO. Fifty samples of L. columella, with shell 6±1mm long, were submitted at 200ml of the solutions in concentrations of 0,47µl/L; 0,76µl/L; 0,94µl/L and 1,51µl/L, during 24 hours. After the experimental event, the snails were placed in solution of Raillet & Henry, for sacrifice and fixation. The results demonstrated lesions characterized by degeneration, necrosis and liquid accumulation in the digestive gland and in the kidney, in samples maintained in concentrations from 0,47 mul/L on.

Registrou-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.

The first occurrence of the Achatina fulica, an intermediate host of Angiostrongylus cantonensis, the etiological agent of meningoencephalic angiostrongiliasis, is reported in Resende municipality, Brazil. In the five visited localities, snails were found living freely, and the larvae of this parasite was not seen in any of them. The finding of A. fulica in the area may be related to its commercialization as a food item and embodies the possibility of new focus.

Registrou-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.

The first occurrence of the Achatina fulica, an intermediate host of Angiostrongylus cantonensis, the etiological agent of meningoencephalic angiostrongiliasis, is reported in Resende municipality, Brazil. In the five visited localities, snails were found living freely, and the larvae of this parasite was not seen in any of them. The finding of A. fulica in the area may be related to its commercialization as a food item and embodies the possibility of new focus.

The use of the latex of Euphorbia splendens var. hislopii was considered as an effective control method for Biomphalaria glabrata in Sumidouro, Rio de Janeiro. However, the appearance and expansion of the snail Melanoides tuberculata since August 1997, with the concomitant reduction of the population of B. glabrata suggest that competitive exclusion might be taking place. Depending on the susceptibility of the thiarid to the E. splendens toxin, the natural control that is occurring could be interrupted by the employment of the latex if the planorbid were less susceptible to the toxin. The aim of this study is to investigate the molluscicidal activity of the latex on M. tuberculata. We used 420 M. tuberculata, from Sumidouro. Fourteen different latex concentrations were tested using World Health Organization general methodology. Probit analysis was used for LD90 and LD50 determination. The LD50 was 3.57 mg/l and LD90 was 6.22 mg/l. At the highest concentration (10 mg/l) there was no survival. No significant differences among replicas (chi2 = 8.31; gl = 13; p > 0.05) were found. The LD90 dose for M. tuberculata was 13.8 times greater than that for B. glabrata, so that the molluscicide in the presence of the thiarid may have a synergic effect on reduction of Biomphalaria populations.

The latex of Euphorbia splendens var. hislopii, at concentrations between 5 to 12 mg/l, kills 100% of the population of Biomphalaria glabrata in a lentic habitat, after 24 h. The lyophilized latex, stocked for 18 months, killed only 34.2% of the snails, at the concentration of 5 mg/l, and 96.0% at 12 mg/l. No lethal effect was observed among Pomacea haustrum exposed to the same concentrations of the molluscicide.