Schistosomiasis as a neglected disease is second to malaria in its adverse effect to public health and socioeconomics impact in the tropics and sub-tropical of the developing countries where 90% of 249 million people ...Schistosomiasis as a neglected disease is second to malaria in its adverse effect to public health and socioeconomics impact in the tropics and sub-tropical of the developing countries where 90% of 249 million people affected are found in Africa. Mwea irrigation scheme in Kenya is infested with Biomphalaria spp. and the research set out to find their susceptibility to Schistosoma mansoni miracidia. Vector snails’ samples were taken from endemic region of Mwea irrigation farmlands and were morphological identified and then cultured. The miracidia exposed snails were transferred into aquaria and after four weeks of exposure they were examined for cercaria shedding twice every week under direct sunlight illumination. It was found that Mwea irrigation scheme was dominantly infested by Biomphalaria pfeifferi. From the morphological parameters of B. pfeifferi it was found that there was no statistical difference in physical characteristics between resistant and susceptible populations. The results in this study showed that the mean value of infection for the Field, F1 and F2 snail samples were 36.6 ± 3.72, 1.93 ± 1.46, 0.36 ± 0.049 respectively and the infection rate decreased from the field snail samples through F2 snail samples. This suggested that the exhibited resistant traits may be due to snail internal defense mechanisms rather than morphological characteristics and this could be thought that the various levels of B. pfeifferi susceptibility to S. mansoni is attributed to genetic variations within a population. Finally, the findings generated in this study, under laboratory condition, suggest that S. mansoni resistant population of B. pfeifferi can be isolated and mass reared with a view of diversifying biological control measures of the vector in Mwea irrigation scheme in Kenya.展开更多
本实验对倪氏复口吸虫(Diplostomum niedashui Pan et Wang,1963)和湖北复口吸虫(Diplostomum hupehensis Pan et Wang,1963)生活史的各个时期,包括虫卵、毛蚴、母胞蚴、子胞蚴、尾蚴、后囊蚴和成虫,进行了详细的观察。两种复口吸虫的...本实验对倪氏复口吸虫(Diplostomum niedashui Pan et Wang,1963)和湖北复口吸虫(Diplostomum hupehensis Pan et Wang,1963)生活史的各个时期,包括虫卵、毛蚴、母胞蚴、子胞蚴、尾蚴、后囊蚴和成虫,进行了详细的观察。两种复口吸虫的第一中间寄主为斯氏萝卜螺(Radix swinhoei(H.Adams));第二中间寄主为鲤形目的鲤科(Cyprinidae)鱼类,鳅科(Cobitidae)的大鳞副泥鳅(P.dabryanus);鳉形目(Cyprinodontiformes)的食蚊鱼(Gambusia affinis);合鳃目的黄鳝(Monopterus albus);鲈形目的罗非鱼(Tilapia mossambica)等淡水鱼类。终末寄主为红咀鸥(Larus ridibundus ridibundus L.)。展开更多
The effects of sublethal concentrations of methanol extract of sesbania sesban plant on survival rate, egg laying of Bulinus truncatus snails, hatchability of their eggs, infection rate with Schistosoma haemato- bium ...The effects of sublethal concentrations of methanol extract of sesbania sesban plant on survival rate, egg laying of Bulinus truncatus snails, hatchability of their eggs, infection rate with Schistosoma haemato- bium miracidia, cercarial production and certain physiological parameters of treated snails were stu- died. The sublethal concentrations of the tested plant extract (LC0, LC10 and LC25) caused considerable reduction in survival rates;egg production of B. runcates snails;hatchability of eggs as well as in the infectivity of Schistosoma haematobium miracidia to the snail. Also, the tested concentrations reduced the cercarial production per snail and the period of cer-carial shedding. The glucose level in haemolymph of exposed snails was elevated while the glycogen, pro-tein content and the activities of hexokinase (HK), pyruvatekinase (PK) and lactate dehydrogenase (LDH) showed a decrease in soft tissues when compared with the control group. It was concluded that the app lication of sublethal concentration of methanol ex- tracts of Sesania sesban may be helpful in snail con- trol as it interferes with the snails’ biology and phy- siology.展开更多
Background: Two aspects need to be considered for schistosomiasis control: morbidity and transmission. In this context, many soluble substances have been tested and Euphorbia milii latex is one of the most promising B...Background: Two aspects need to be considered for schistosomiasis control: morbidity and transmission. In this context, many soluble substances have been tested and Euphorbia milii latex is one of the most promising Brazilian molluscicides. Phytochemical studies involving simulation of the applicability of this latex on all aquatic forms of the S. mansoni life cycle are rare in the literature. The aim of this work was to evaluate the effect of E. milii latex on S. mansoni in the egg, miracidium and different developmental stages in Biomphalaria glabrata. Methods: The laboratory study was designed to simulate the different forms of exposure of the life cycle stages of S. mansoni to the LC50 of E. milii latex;we tested the exposition from four situations of S. mansoni contact with the latex and observed the exposure on different snails’ infection stage too. All snails were analyzed weekly for cercarial shedding and reproductive biology. Results: The results showed that contact of S. mansoni eggs and miracidia with the LC50 of E. milii negatively influenced the development of the parasite life cycle in the intermediate host, with consequent reduction of cercarial shedding. The exposure of infected snails affected the reproductive biology and cercarial shedding in all intra-mollusk development stages of S. mansoni, but the reduction was greater in the first, fourth, fifth, sixth, seventh and eighth weeks of infection. The LC50 of E. milii latex had toxic action on eggs and miracidia, and the number of cercariae shed by snails during the study period declined by about 80%. Conclusions: We can conclude that the use of natural biodegradable compounds containing low concentrations of substances already characterized as having eco-toxico- logical potential can be an important tool to reduce the transmission of Schistosomiasis.展开更多
文摘Schistosomiasis as a neglected disease is second to malaria in its adverse effect to public health and socioeconomics impact in the tropics and sub-tropical of the developing countries where 90% of 249 million people affected are found in Africa. Mwea irrigation scheme in Kenya is infested with Biomphalaria spp. and the research set out to find their susceptibility to Schistosoma mansoni miracidia. Vector snails’ samples were taken from endemic region of Mwea irrigation farmlands and were morphological identified and then cultured. The miracidia exposed snails were transferred into aquaria and after four weeks of exposure they were examined for cercaria shedding twice every week under direct sunlight illumination. It was found that Mwea irrigation scheme was dominantly infested by Biomphalaria pfeifferi. From the morphological parameters of B. pfeifferi it was found that there was no statistical difference in physical characteristics between resistant and susceptible populations. The results in this study showed that the mean value of infection for the Field, F1 and F2 snail samples were 36.6 ± 3.72, 1.93 ± 1.46, 0.36 ± 0.049 respectively and the infection rate decreased from the field snail samples through F2 snail samples. This suggested that the exhibited resistant traits may be due to snail internal defense mechanisms rather than morphological characteristics and this could be thought that the various levels of B. pfeifferi susceptibility to S. mansoni is attributed to genetic variations within a population. Finally, the findings generated in this study, under laboratory condition, suggest that S. mansoni resistant population of B. pfeifferi can be isolated and mass reared with a view of diversifying biological control measures of the vector in Mwea irrigation scheme in Kenya.
文摘本实验对倪氏复口吸虫(Diplostomum niedashui Pan et Wang,1963)和湖北复口吸虫(Diplostomum hupehensis Pan et Wang,1963)生活史的各个时期,包括虫卵、毛蚴、母胞蚴、子胞蚴、尾蚴、后囊蚴和成虫,进行了详细的观察。两种复口吸虫的第一中间寄主为斯氏萝卜螺(Radix swinhoei(H.Adams));第二中间寄主为鲤形目的鲤科(Cyprinidae)鱼类,鳅科(Cobitidae)的大鳞副泥鳅(P.dabryanus);鳉形目(Cyprinodontiformes)的食蚊鱼(Gambusia affinis);合鳃目的黄鳝(Monopterus albus);鲈形目的罗非鱼(Tilapia mossambica)等淡水鱼类。终末寄主为红咀鸥(Larus ridibundus ridibundus L.)。
基金supported by grants from the Key Project of National Science and Technology Support Programme(2009BAI78B05)Deutsche Forschungsgemeinschaft(DFG)(KO4136/1-1)the Key Laboratory of Immune and Control Schistosomiasis and Key Subject Development Special Program of Hunan Province,P.R.China(YZ2010-27)
文摘The effects of sublethal concentrations of methanol extract of sesbania sesban plant on survival rate, egg laying of Bulinus truncatus snails, hatchability of their eggs, infection rate with Schistosoma haemato- bium miracidia, cercarial production and certain physiological parameters of treated snails were stu- died. The sublethal concentrations of the tested plant extract (LC0, LC10 and LC25) caused considerable reduction in survival rates;egg production of B. runcates snails;hatchability of eggs as well as in the infectivity of Schistosoma haematobium miracidia to the snail. Also, the tested concentrations reduced the cercarial production per snail and the period of cer-carial shedding. The glucose level in haemolymph of exposed snails was elevated while the glycogen, pro-tein content and the activities of hexokinase (HK), pyruvatekinase (PK) and lactate dehydrogenase (LDH) showed a decrease in soft tissues when compared with the control group. It was concluded that the app lication of sublethal concentration of methanol ex- tracts of Sesania sesban may be helpful in snail con- trol as it interferes with the snails’ biology and phy- siology.
文摘Background: Two aspects need to be considered for schistosomiasis control: morbidity and transmission. In this context, many soluble substances have been tested and Euphorbia milii latex is one of the most promising Brazilian molluscicides. Phytochemical studies involving simulation of the applicability of this latex on all aquatic forms of the S. mansoni life cycle are rare in the literature. The aim of this work was to evaluate the effect of E. milii latex on S. mansoni in the egg, miracidium and different developmental stages in Biomphalaria glabrata. Methods: The laboratory study was designed to simulate the different forms of exposure of the life cycle stages of S. mansoni to the LC50 of E. milii latex;we tested the exposition from four situations of S. mansoni contact with the latex and observed the exposure on different snails’ infection stage too. All snails were analyzed weekly for cercarial shedding and reproductive biology. Results: The results showed that contact of S. mansoni eggs and miracidia with the LC50 of E. milii negatively influenced the development of the parasite life cycle in the intermediate host, with consequent reduction of cercarial shedding. The exposure of infected snails affected the reproductive biology and cercarial shedding in all intra-mollusk development stages of S. mansoni, but the reduction was greater in the first, fourth, fifth, sixth, seventh and eighth weeks of infection. The LC50 of E. milii latex had toxic action on eggs and miracidia, and the number of cercariae shed by snails during the study period declined by about 80%. Conclusions: We can conclude that the use of natural biodegradable compounds containing low concentrations of substances already characterized as having eco-toxico- logical potential can be an important tool to reduce the transmission of Schistosomiasis.
