Background:Given that increase in temperature may alter host-parasite relationships,the anticipated rise in temperature due to global warming might change transmission patterns of certain diseases.However,the extent t...Background:Given that increase in temperature may alter host-parasite relationships,the anticipated rise in temperature due to global warming might change transmission patterns of certain diseases.However,the extent to which this will happen is not well understood.Methods:Using a host-parasite system involving Bulinus globosus and Schistosoma haematobium,we assessed the effect of temperature on snail fecundity,growth,survival and parasite development under laboratory conditions.Results:Our results show that temperature may have a non-linear effect on snail fecundity and snail growth.Snails maintained at 15.5℃ and 36.0℃ did not produce egg masses while those maintained at 25.8℃ laid 344 and 105 more egg masses than snails at 31.0℃ and 21.2℃,respectively.Attainment of patency led to a reduction in egg mass production among the snails.However,the reduction in fecundity for snails maintained at 21.2℃ occurred before snails started shedding cercariae.Parasite development was accelerated at high temperatures with snails maintained at 31.0℃ reaching patency after three weeks.Furthermore,snail growth rate was highest at 25.8℃ while it was inhibited at 15.5℃ and reduced at 31.0℃.Increase in temperature increased snail mortality rates.Snails maintained at 36.0℃ had the shortest survival time while those maintained at 15.5℃ had the longest survival time.Conclusions:We concluded that temperature influences fecunxdity,growth,survival and parasite development in the snail and thus dictates the time it takes the parasite to complete the life cycle.This has implications on transmission of schistosomiasis in the context of global warming.展开更多
Background: Bulinus globosus,the main intermediate snail host of Schistosoma haematobium.The increased contacts between Africa and China could even lead to large-scale dissemination of B.globosus in China.Temperature ...Background: Bulinus globosus,the main intermediate snail host of Schistosoma haematobium.The increased contacts between Africa and China could even lead to large-scale dissemination of B.globosus in China.Temperature is the key factor affecting fresh-water snail transmission.This study predicted potential risk of colonization of B.globosus in the mainland of China under climate change.Methods: We investigated minimum and maximum temperatures for B.globosus eggs,juveniles and adult snails kept under laboratory conditions to find the most suitable range by pinpointing the median effective temperatures(ET50).We also assessed the influence of temperature on spawning and estimated the accumulated temperature(AT).The average air temperatures between 1955 and 2019 in January and July,the coldest and hottest months in China,respectively,were collected from national meteorological monitoring stations and investigated in a geographic information system(GIS)using empirical Bayesian Kriging to evaluate the theoretical possibility for distribution of B.globosus in southern China based on temperature.Results: The effective minimum temperature(ET50min)for eggs,juveniles,adult snails and spawning were 8.5,7.0,7.0,14.9℃,respectively,with the corresponding maximum values(ET50max)of 36.6,40.5,40.2 and 38.1℃.The AT was calculated at 712.1±64.9℃·d.In 1955,the potential B.globosus distribution would have had a northern boundary stretching from the coastal areas of Guangdong Province and Guangxi Autonomous Region to southern Yunnan Province.Since then,this line has gradually moved northward.Conclusions: Annual regeneration of B.globosus can be supported by the current climate conditions in the mainland of China,and a gradual expansion trend from south to north is shown in the study from 2015 to 2019.Thus,there is a potential risk of colonization of B.globosus in the mainland of China under climate change.展开更多
Schistosomiasis is a public health concern in Benin. Freshwater snails of the genus Bulinus serve as intermediate hosts for schistosomes, trematode parasites responsible for bilharzia. The urinary form, caused by Schi...Schistosomiasis is a public health concern in Benin. Freshwater snails of the genus Bulinus serve as intermediate hosts for schistosomes, trematode parasites responsible for bilharzia. The urinary form, caused by Schistosoma haematobium, is the most widespread and is transmitted to humans by these mollusks, with Bulinus truncatus and Bulinus globosus being the most important species. Effective strategies to combat the transmission of these parasites require a prior understanding of the molecular characterization of Bulinus snails. For this purpose, 293 Bulinus snails were collected and morphologically identified from two localities in southern Benin, Sô-Ava and Azowlissè. The snails were preserved in absolute alcohol. To achieve the set objectives, DNA was extracted from the collected biological material, and SSU gene fragments were amplified. Using PCR-RFLP, the amplified fragments were digested with the restriction endonucleases HaeIII, HinfI, and DdeI to perform molecular characterization. In this study, 80 individuals of B. globosus and 10 of B. truncatus were subjected to molecular analysis. The PCR-RFLP profiles showed bands of different sizes for the Bulinus species when analyzed with the three endonucleases using the SSU molecular marker. PCR-RFLP analysis revealed that the snails belonged to the freshwater genus Bulinus, including Bulinus globosus and B. truncatus, based on reference profiles from studies conducted in Nigeria, which enabled precise identification of these gastropods. This study provided initial insights, although still incomplete, into the molecular diversity of these species.展开更多
基金The study received financial support from University of KwaZulu-Natal College of Health Sciences through the student scholarship programme,and from United Nations International Children's Fund/United Nations Development Programme/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseasesfrom the Canadian International Development Research Centre through their support towards a Malaria and Bilharzia in Southern Africa project.
文摘Background:Given that increase in temperature may alter host-parasite relationships,the anticipated rise in temperature due to global warming might change transmission patterns of certain diseases.However,the extent to which this will happen is not well understood.Methods:Using a host-parasite system involving Bulinus globosus and Schistosoma haematobium,we assessed the effect of temperature on snail fecundity,growth,survival and parasite development under laboratory conditions.Results:Our results show that temperature may have a non-linear effect on snail fecundity and snail growth.Snails maintained at 15.5℃ and 36.0℃ did not produce egg masses while those maintained at 25.8℃ laid 344 and 105 more egg masses than snails at 31.0℃ and 21.2℃,respectively.Attainment of patency led to a reduction in egg mass production among the snails.However,the reduction in fecundity for snails maintained at 21.2℃ occurred before snails started shedding cercariae.Parasite development was accelerated at high temperatures with snails maintained at 31.0℃ reaching patency after three weeks.Furthermore,snail growth rate was highest at 25.8℃ while it was inhibited at 15.5℃ and reduced at 31.0℃.Increase in temperature increased snail mortality rates.Snails maintained at 36.0℃ had the shortest survival time while those maintained at 15.5℃ had the longest survival time.Conclusions:We concluded that temperature influences fecunxdity,growth,survival and parasite development in the snail and thus dictates the time it takes the parasite to complete the life cycle.This has implications on transmission of schistosomiasis in the context of global warming.
文摘Background: Bulinus globosus,the main intermediate snail host of Schistosoma haematobium.The increased contacts between Africa and China could even lead to large-scale dissemination of B.globosus in China.Temperature is the key factor affecting fresh-water snail transmission.This study predicted potential risk of colonization of B.globosus in the mainland of China under climate change.Methods: We investigated minimum and maximum temperatures for B.globosus eggs,juveniles and adult snails kept under laboratory conditions to find the most suitable range by pinpointing the median effective temperatures(ET50).We also assessed the influence of temperature on spawning and estimated the accumulated temperature(AT).The average air temperatures between 1955 and 2019 in January and July,the coldest and hottest months in China,respectively,were collected from national meteorological monitoring stations and investigated in a geographic information system(GIS)using empirical Bayesian Kriging to evaluate the theoretical possibility for distribution of B.globosus in southern China based on temperature.Results: The effective minimum temperature(ET50min)for eggs,juveniles,adult snails and spawning were 8.5,7.0,7.0,14.9℃,respectively,with the corresponding maximum values(ET50max)of 36.6,40.5,40.2 and 38.1℃.The AT was calculated at 712.1±64.9℃·d.In 1955,the potential B.globosus distribution would have had a northern boundary stretching from the coastal areas of Guangdong Province and Guangxi Autonomous Region to southern Yunnan Province.Since then,this line has gradually moved northward.Conclusions: Annual regeneration of B.globosus can be supported by the current climate conditions in the mainland of China,and a gradual expansion trend from south to north is shown in the study from 2015 to 2019.Thus,there is a potential risk of colonization of B.globosus in the mainland of China under climate change.
文摘Schistosomiasis is a public health concern in Benin. Freshwater snails of the genus Bulinus serve as intermediate hosts for schistosomes, trematode parasites responsible for bilharzia. The urinary form, caused by Schistosoma haematobium, is the most widespread and is transmitted to humans by these mollusks, with Bulinus truncatus and Bulinus globosus being the most important species. Effective strategies to combat the transmission of these parasites require a prior understanding of the molecular characterization of Bulinus snails. For this purpose, 293 Bulinus snails were collected and morphologically identified from two localities in southern Benin, Sô-Ava and Azowlissè. The snails were preserved in absolute alcohol. To achieve the set objectives, DNA was extracted from the collected biological material, and SSU gene fragments were amplified. Using PCR-RFLP, the amplified fragments were digested with the restriction endonucleases HaeIII, HinfI, and DdeI to perform molecular characterization. In this study, 80 individuals of B. globosus and 10 of B. truncatus were subjected to molecular analysis. The PCR-RFLP profiles showed bands of different sizes for the Bulinus species when analyzed with the three endonucleases using the SSU molecular marker. PCR-RFLP analysis revealed that the snails belonged to the freshwater genus Bulinus, including Bulinus globosus and B. truncatus, based on reference profiles from studies conducted in Nigeria, which enabled precise identification of these gastropods. This study provided initial insights, although still incomplete, into the molecular diversity of these species.
