Schistosomiasis

2010 ◽  
pp. 1202-1212
Author(s):  
D.W. Dunne ◽  
B.J. Vennervald
Keyword(s):  
Life Cycle ◽  
Middle East ◽  
South America ◽  
East Asia ◽  
Fresh Water ◽  
Freshwater Snail ◽  
Snail Host ◽  
Vertebrate Host ◽  
South East Asia ◽  
Intact Skin

Schistosomiasis is caused by trematode worms Schistosoma spp., whose life cycle requires a definitive vertebrate host and an intermediate freshwater snail host. Transmission to humans occurs through exposure to fresh water containing infectious larvae, which can penetrate intact skin before developing into blood-dwelling adult worms. The disease is patchily distributed in parts of South America, Africa, the Middle East, China, and South East Asia, with about 200 million people infected and 20 million suffering severe consequences of infection....

Schistosomiasis

2020 ◽  
pp. 1540-1551
Author(s):  
David Dunne ◽  
Birgitte Vennervald
Keyword(s):  
Life Cycle ◽  
Chronic Disease ◽  
South America ◽  
Clinical Manifestations ◽  
Freshwater Snail ◽  
Snail Host ◽  
Control Measures ◽  
Vertebrate Host ◽  
Infected People ◽  
Drug Of Choice

Schistosomiasis is caused by trematode worms Schistosoma spp., whose life cycle requires a definitive vertebrate host and an intermediate freshwater snail host. Transmission to humans occurs through exposure to fresh water containing infectious larvae, which can penetrate intact skin before developing into blood-dwelling adult worms. The disease is patchily distributed in parts of South America, Africa, the Middle East, China, and Southeast Asia, with about 200 million people infected and 20 million suffering severe consequences of infection. Most infected people living in endemic areas have few (if any) overt symptoms, but clinical manifestations (when present) depend on the stage of infection. Praziquantel is the drug of choice, with corticosteroids added in cases of Katayama fever. Acute schistosomiasis responds well, but chronic disease less so, but rapid re-exposure and reinfection are common (particularly in young children) unless control measures are implemented at the community level.

Effects of land use on intermediate snail host fauna, abundance, distribution and cercariae infection rate in Omo-Gibe river basin, Ethiopia

2020 ◽  
Author(s):  
Ketema Deribew ◽  
Etana Jaleta ◽  
Belayhun Mandefro ◽  
Zeleke Mekonnen ◽  
Delenasaw Yewhalaw ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Fresh Water ◽  
River Basin ◽  
Anthropogenic Activities ◽  
Freshwater Snail ◽  
Snail Host ◽  
Snail Species ◽  
Intermediate Hosts ◽  
Biomphalaria Pfeifferi

Abstract Background: Land use and land cover change significantly affects biodiversity, abundance and distribution of intermediate snail host fauna. In Omo-Gibe river basin the extent of land-use change is high due to anthropogenic activities leading to habitat change of freshwater snail intermediate hosts. Most intermediate snail hosts of human Schistosome parasites belong to two genera, Biomphalaria and Bulinus. In Addition, Lymnea spp. is another important host of Fasciola which causes fasciolasis in domestic animals and human. This study aims to assess the effects of land-use on the distribution and abundance of freshwater snail intermediate hosts and cercariae infection rates of fresh water intermediate snail hosts in Omo-Gibe River basin, Ethiopia.Methods: This study was conducted in Omo-Gibe river basin in 130 sampling sites which include rivers, lakes, dams, stream, wetlands and irrigation ditches. At each site data on land use, anthropogenic activities, freshwater snail abundance and species diversity, and water samples were collected. Snails were collected from each sampling sites using a scoop (20cm x 30cm) with a mesh size of 300µm. Snails were sorted by genus on Enamel pan using forceps and preserved in labeled vials containing 75% ethanol. Live snails collected from the same habitat were sorted carefully and put in clean plastic buckets half filled with water. Afterwards, snails were provided with fresh lettuce leaves and maintained in the laboratory. Snails were then identified morphologically to family, genus and to species level. Each snail was examined for cercaria shedding by placing in a petri dish containing water and exposed to the sun for 2 hours. Cercariae were morphologically identified by microscopy. ArcGIS software of version 10.3.1 was used to map snail distribution and data were analysed using SPSS version-20.Results: The results obtained in this study shows clearly that land use change affect the distribution and abundance of fresh water snails in Omo-Gibe river basin. Fresh water snails were more abundant in farmland and settlement areas. Of the total 2,559 freshwater snails collected from 130 surveyed sites in Omo-Gibe river basin, 1749 (68.34%) belongs to medically important snail species. Biomphalaria spp.914 (35.7%),, Lymnea spp.439 (17.1%),, Physa spp. 343(13.4%) and Bulinus spp 53 (2%)). Sphaeriidae group accounted for 810 (31.6%) of the collected specimens. Biomphalaria pfeifferi was the predominant species of the total snail sampled from lakes, wetlands, rivers and irrigation ditches. Biomphalaria pfeifferi was the most infected snail species by different cercariae. Bulinus globosus and L.natalensis were infected by more than one and same type of cercariae. However, none of B. sudanica and P. acuta specimens was infected by trematode.Conclusions: The results of this study revealed that land use change altered the abundance, distribution and diversity of medically important fresh water snails in the study area. In general medically important freshwater snails which include: Biomphalaria spp, Bulinus spp and Lymnaea spp were collected from lakes, rivers, wetlands, irrigation ditches.. The medically important snail species found infected by cercaria are L. natalensis, B. pfeifferi and B. globosus. Biomphalaria pfefferi was the predominant species and highly infected by cercariae. Higher infection rate was observed in snails collected in Farmland (16.59%) and Grassland (36.6%).

14. Détente in Decline, 1977–9

2013 ◽  
Author(s):  
John W. Young ◽  
John Kent
Keyword(s):  
Civil War ◽  
Soviet Union ◽  
Middle East ◽  
East Asia ◽  
Policy Making ◽  
Peace Treaty ◽  
South East Asia ◽  
Jimmy Carter ◽  
Richard Nixon ◽  
The Soviet Union

This chapter examines the decline of détente during the period 1977–1979. Détente suffered in part from being identified with Richard Nixon. After 1973, conservatives increasingly questioned détente, felt that the Strategic Arms Limitation Talks (SALT I) benefited the Soviet Union most, and were disturbed by an apparent pattern of communist adventurism abroad, in the 1973 Middle East War, Angola, and South-East Asia. The chapter first considers détente and policy-making during the time of Jimmy Carter before discussing the conflict in the Middle East, in particular the Lebanon Civil War, and the Camp David summit of 1978 that resulted in an Egyptian–Israel peace treaty. It then analyses the Ogaden conflict of 1977–1978), the ‘normalization’ of Sino-American relations, and the Sino–Vietnamese War. It concludes with an assessment of the SALT II treaty.

From Ancient Times to the Year 1000

2018 ◽  
Author(s):  
Tim Dyson
Keyword(s):  
Middle East ◽  
East Asia ◽  
Total Population ◽  
Second Century ◽  
South East Asia ◽  
Southern Europe ◽  
The North ◽  
Ancient Times ◽  
River Valleys ◽  
Different Parts

This chapter addresses the period from the end of the Mauryan Empire to c.1000 CE. There is very little evidence for the period. Nevertheless, people probably continued to migrate into river valleys and exploit new land. As a result, populations in different parts of the subcontinent increased—albeit usually very slowly and irregularly. In the north, Indo-Aryan influences continued to grow. Further south, kingdoms like those of the Pallavas and Cholas were crucial to the process of ‘Indianization’ which, from about the second century CE, affected areas of south-east Asia. It seems unlikely that India’s people were badly affected by the so-called ‘Plague of Justinian’ which affected parts of the Middle East and southern Europe during the sixth century. The chapter considers evidence collected around 640 CE by the Chinese visitor Hsuan Tsang and suggests that it is consistent with a total population of anywhere between 30 and 85 million.

Phylogeny of the Hebe Complex (Scrophulariaceae: Veroniceae)

1993 ◽  
Vol 6 (5) ◽  
pp. 457 ◽  
Author(s):  
PJ Garnock-Jones
Keyword(s):  
New Zealand ◽  
South America ◽  
East Asia ◽  
Cladistic Analysis ◽  
New Guinea ◽  
South East Asia ◽  
New Combinations ◽  
Vegetation Types ◽  
Dispersal Events ◽  
Occurrence Of Species

The southern segregates of Veronica (Hebe, Parahebe, Chionohebe, Dementia, and Detzneria) form a monophyletic assemblage of c. 144 species found in New Guinea, Australia, New Zealand, Rapa, and South America. Most of the species occur in New Zealand, where Hebe is the largest genus and a characteristic member of many vegetation types. Cladistic analysis of the Hebe complex, based on 45 characters and 22 terminal taxa, indicates that: (1) Hebe is monophyletic if Hebe 'Paniculatae' is excluded and H. formosa is included; (2) Parahebe is paraphyletic; (3) Chionohebe is monophyletic, but is part of a larger clade which includes alpine Parahebe and possibly the monotypic Detzneria; (4) Hebe 'Paniculatae', Derwentia, and New Guinea Parahebe are monophyletic basal groups in the complex. According to this study, recognition of monophyletic genera would require six genera in the complex, supporting the recognition of Derwentia and separation of Hebe 'Paniculatae' from Hebe. Leonohebe Heads is considered polyphyletic and is not accepted; new combinations are provided for two species of Leonohebe with no name at species rank in Hebe. Competing biogeographic hypotheses have implied (1) a Gondwanan origin, or (2) migration from South-east Asia via New Guinea. An origin in Australasia from Asian ancestors best explains the topology of the basal parts of the cladogram, but at least seven dispersal events from New Zealand are postulated to explain the occurrence of species of Hebe in South America and Rapa and Parahebe, Hebe, and Chionohebe in Australia. An hypothesis which did not allow dispersal would require that nearly all the evolution in the complex occurred before the Tertiary, and hardly any since.

The adipocyte life cycle hypothesis

2005 ◽  
Vol 110 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jessica Smith ◽  
Maha Al-Amri ◽  
Prabhakaran Dorairaj ◽  
Allan Sniderman
Keyword(s):  
Adipose Tissue ◽  
Life Cycle ◽  
Fatty Acid ◽  
East Asia ◽  
South East Asia ◽  
Adipocyte Size ◽  
Triacylglycerol Synthesis ◽  
Life Cycle Hypothesis ◽  
Metabolic Properties ◽  
Consequences Of Obesity

The adipocyte life cycle hypothesis states that the metabolic properties of an adipocyte vary predictably during its life cycle: that as an adipocyte matures, it accumulates triacylglycerol (triglyceride) and becomes larger; that the rates of triacylglycerol synthesis and lipolysis are matched within adipocytes and that larger adipocytes, in general, have greater rates of triacylglycerol synthesis and, concurrently, greater rates of lipolysis and, therefore, larger adipocytes have greater rates of transmembrane fatty acid flux; and that the secretion of cytokines can also be related to adipocyte size with larger adipocytes having a more unfavourable profile of cytokine secretion than smaller adipocytes. Adipocyte location is an important modifier of this relationship and the favoured sites of adipocyte proliferation are a function of gender and the position within the life cycle of the organism at which proliferation occurs. The adipocyte life cycle hypothesis posits that the metabolic consequences of obesity depend on whether expansion of adipose tissue is achieved primarily by an increase in adipocyte number or adipocyte size. This hypothesis may explain a variety of previously unanswered clinical puzzles such as the vulnerability of many peoples from South East Asia to the adverse metabolic consequences of obesity.

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