RESUMEN
Abstract Fluctuations in population density of planorbid hosts of S. mansoni are influenced by climatic factors. The knowledge about interference from changes in water temperature in these populations is an important aspect of the epidemiology of schistosomiasis. In this experiment, it is explored the influence of different temperatures on the development of Schistosoma mansoni in Biomphalaria glabrata melanic and albino variants. The results indicated an intrinsic relationship between temperature and development of the parasite in the intramollusc phase, independent of the pigmentation of the mantle of the molluscs. The higher the temperature, the shorter the period necessary for the development of the parasite was while the higher the mortality of infected mollusks. It is concluded that, in the presence of climate change, the increasement of temperature in cold and flooded regions may encourage the establishment of new foci of transmission of schistosomiasis by changing the geographic extent and extending the epidemiological transmission potential. In warm climates, higher temperatures, however, could compromise the transmission of the disease because of biological stress suffered by parasite and host. Under these conditions, it can result in the death of the parasite or a change in their ability to infect new host species of molluscs in new areas. Mantle pigmentation patterns in molluscs have not shown significant interference in the development of the parasite.
Resumo Flutuações na densidade populacional de planorbídeos hospedeiros do S. mansoni são influenciadas por fatores climáticos. O conhecimento sobre a interferência de alterações na temperatura da água nestas populações é um aspecto importante da epidemiologia da esquistossomose. Neste experimento avaliou-se a influência de diferentes temperaturas no desenvolvimento de Schistosoma mansoni em Biomphalaria glabrata variantes melânica e albina. Os resultados indicaram uma relação intrínseca entre temperatura e desenvolvimento do parasito na fase intramolusco, independente da pigmentação do manto dos moluscos. Quanto mais elevada a temperatura, menor o período necessário para desenvolvimento do parasito e maior mortalidade dos moluscos infectados. Conclui-se que, na presença de alterações climáticas, o aumento da temperatura em regiões frias e alagadas poderá favorecer o estabelecimento de novos focos de transmissão da esquistossomose alterando a extensão geográfica e ampliando o potencial epidemiológico da transmissão. Em regiões de clima quente, o aumento da temperatura, por sua vez, poderá comprometer a transmissão da doença em virtude do estresse biológico sofrido por parasito e hospedeiro. Nestas condições, poderá ocorrer a morte do parasito ou uma alteração na sua habilidade de infectar novas espécies de moluscos hospedeiros em novas áreas. Padrões de pigmentação do manto nos moluscos não demonstraram interferência significativa no desenvolvimento do parasita.
Asunto(s)
Animales , Schistosoma mansoni/patogenicidad , Temperatura , Biomphalaria/parasitología , Esquistosomiasis mansoni/etiología , Cambio Climático , Pigmentación , AlbinismoRESUMEN
Biomphalaria amazonica is a planorbid species considered a potential host of Schistosoma mansoni. It is widely distributed in the Neotropical zone, particularly in the North and Centre-West of Brazil and in the North of Bolivia. The aim of the present study was to determine the host-parasite relationship between B. amazonica and S. mansoni (BH and SJ strains). Specimens of B. amazonica and their snail-conditioned water were examined in terms of their ability to attract miracidia. The infectivity of the mollusks was determined by exposing them to 20 miracidia of both strains. Sporocyst development and amebocyte reactions were studied after each mollusk specimen was exposed to 100 miracidia. Although no cercariae were eliminated, specimens of B. amazonica proved capable of attracting 77% of the miracidia they were exposed to. Viable sporocysts with no amebocyte reaction were found 96 hours after the exposure to miracidia. These results indicate the susceptibility of B. amazonica to the BH and SJ strains of S. mansoni, and therefore demonstrate the importance of this planorbid species as a potential vector of the trematode in the areas where it occurs.(AU)
Biomphalaria amazonica é uma espécie de planorbídeo considerada vetora potencial do Schistosoma mansoni. É amplamente distribuída na zona neotropical, especialmente no Norte e Centro-Oeste do Brasil e Norte da Bolívia. O presente trabalho teve por objetivo estudar a relação parasito-hospedeiro entre B. amazonica e S. mansoni (linhagens BH e SJ). Espécimes de B. amazonica e sua água de condicionamento foram examinados em relação à sua capacidade de atração miraxonal. A infectividade dos moluscos foi testada expondo-os a 20 miracídios de ambas as linhagens. A viabilidade dos esporocistos e o desenvolvimento de reações amebocitárias foram estudados após cada molusco ser exposto a 100 miracídios. Apesar de não eliminarem cercárias, B. amazonica provou ser capaz de atrair 77% dos miracídios a que foram expostos. Esporocistos viáveis sem reação amebócitaria foram encontrados 96 horas após a exposição aos miracídios. Esses resultados indicam a suscetibilidade de B. amazonica às linhagens BH e SJ de S. mansoni e, portanto, demonstram a importância desta espécie de planorbídeo como um vetor potencial do trematodeo na área onde ele ocorre.(AU)
Asunto(s)
Biomphalaria/parasitología , Schistosoma mansoni/fisiología , Interacciones Huésped-Parásitos , Estudios EpidemiológicosRESUMEN
Abstract Biomphalaria amazonica is a planorbid species considered a potential host of Schistosoma mansoni. It is widely distributed in the Neotropical zone, particularly in the North and Centre-West of Brazil and in the North of Bolivia. The aim of the present study was to determine the host-parasite relationship between B. amazonica and S. mansoni (BH and SJ strains). Specimens of B. amazonica and their snail-conditioned water were examined in terms of their ability to attract miracidia. The infectivity of the mollusks was determined by exposing them to 20 miracidia of both strains. Sporocyst development and amebocyte reactions were studied after each mollusk specimen was exposed to 100 miracidia. Although no cercariae were eliminated, specimens of B. amazonica proved capable of attracting 77% of the miracidia they were exposed to. Viable sporocysts with no amebocyte reaction were found 96 hours after the exposure to miracidia. These results indicate the susceptibility of B. amazonica to the BH and SJ strains of S. mansoni, and therefore demonstrate the importance of this planorbid species as a potential vector of the trematode in the areas where it occurs.
Resumo Biomphalaria amazonica é uma espécie de planorbídeo considerada vetora potencial do Schistosoma mansoni. É amplamente distribuída na zona neotropical, especialmente no Norte e Centro-Oeste do Brasil e Norte da Bolívia. O presente trabalho teve por objetivo estudar a relação parasito-hospedeiro entre B. amazonica e S. mansoni (linhagens BH e SJ). Espécimes de B. amazonica e sua água de condicionamento foram examinados em relação à sua capacidade de atração miraxonal. A infectividade dos moluscos foi testada expondo-os a 20 miracídios de ambas as linhagens. A viabilidade dos esporocistos e o desenvolvimento de reações amebocitárias foram estudados após cada molusco ser exposto a 100 miracídios. Apesar de não eliminarem cercárias, B. amazonica provou ser capaz de atrair 77% dos miracídios a que foram expostos. Esporocistos viáveis sem reação amebócitaria foram encontrados 96 horas após a exposição aos miracídios. Esses resultados indicam a suscetibilidade de B. amazonica às linhagens BH e SJ de S. mansoni e, portanto, demonstram a importância desta espécie de planorbídeo como um vetor potencial do trematodeo na área onde ele ocorre.
Asunto(s)
Animales , Schistosoma mansoni/fisiología , Biomphalaria/parasitología , Interacciones Huésped-Parásitos , Schistosoma mansoni/crecimiento & desarrollo , Brasil , Quimiotaxis , Oocistos/crecimiento & desarrollo , Oocistos/fisiología , Cercarias/crecimiento & desarrollo , Cercarias/fisiologíaRESUMEN
Biomphalaria amazonica is a planorbid species considered a potential host of Schistosoma mansoni. It is widely distributed in the Neotropical zone, particularly in the North and Centre-West of Brazil and in the North of Bolivia. The aim of the present study was to determine the host-parasite relationship between B. amazonica and S. mansoni (BH and SJ strains). Specimens of B. amazonica and their snail-conditioned water were examined in terms of their ability to attract miracidia. The infectivity of the mollusks was determined by exposing them to 20 miracidia of both strains. Sporocyst development and amebocyte reactions were studied after each mollusk specimen was exposed to 100 miracidia. Although no cercariae were eliminated, specimens of B. amazonica proved capable of attracting 77% of the miracidia they were exposed to. Viable sporocysts with no amebocyte reaction were found 96 hours after the exposure to miracidia. These results indicate the susceptibility of B. amazonica to the BH and SJ strains of S. mansoni, and therefore demonstrate the importance of this planorbid species as a potential vector of the trematode in the areas where it occurs.
Asunto(s)
Biomphalaria/parasitología , Interacciones Huésped-Parásitos , Schistosoma mansoni/fisiología , Animales , Brasil , Cercarias/crecimiento & desarrollo , Cercarias/fisiología , Quimiotaxis , Oocistos/crecimiento & desarrollo , Oocistos/fisiología , Schistosoma mansoni/crecimiento & desarrolloRESUMEN
Fluctuations in population density of planorbid hosts of S. mansoni are influenced by climatic factors. The knowledge about interference from changes in water temperature in these populations is an important aspect of the epidemiology of schistosomiasis. In this experiment, it is explored the influence of different temperatures on the development of Schistosoma mansoni in Biomphalaria glabrata melanic and albino variants. The results indicated an intrinsic relationship between temperature and development of the parasite in the intramollusc phase, independent of the pigmentation of the mantle of the molluscs. The higher the temperature, the shorter the period necessary for the development of the parasite was while the higher the mortality of infected mollusks. It is concluded that, in the presence of climate change, the increasement of temperature in cold and flooded regions may encourage the establishment of new foci of transmission of schistosomiasis by changing the geographic extent and extending the epidemiological transmission potential. In warm climates, higher temperatures, however, could compromise the transmission of the disease because of biological stress suffered by parasite and host. Under these conditions, it can result in the death of the parasite or a change in their ability to infect new host species of molluscs in new areas. Mantle pigmentation patterns in molluscs have not shown significant interference in the development of the parasite.