scholarly journals The geographical distribution and habitats of three liver fluke intermediate hosts in South - Africa and the health implications involved

2008 ◽  
Vol 27 (1) ◽  
pp. 1-16 ◽  
Author(s):  
K. N. De Kock ◽  
C. T. Wolmarans
Keyword(s):  
South Africa ◽  
Geographical Distribution ◽  
Rural Areas ◽  
Liver Fluke ◽  
Freshwater Snail ◽  
Water Bodies ◽  
Intermediate Hosts ◽  
The World ◽  
Cattle Herds ◽  
Human Infections

Account is given of the distribution and habitats of the three Lymnaea species currently on recordin the National Freshwater Snail Collection (NFSC) of South Africa. A total number of 616, 353and 202 loci (1/16th square degrees) was respectively recorded for Lymnaea natalensis, L. columellaand L. truncatula. The number of loci in which the collection sites of each species was located, wasdistributed in intervals of mean annual air temperature and rainfall, as well as intervals of meanaltitude. A temperature index was calculated for all mollusc species in the database and the resultsused to rank them in order of their association with low to high climatic temperatures. Chi-squareand effect size values were calculated to determine the significance in differences between frequencies of occurrence of each species in, on, or at the different options for each of the variables investigated and also to determine the significance of the differences between the three species. None of the three Lymnaea species were well represented in the arid regions of the Northern ,Western and Eastern Cape Province, and only L. truncatula was reported from Lesotho. Lymnaeanatalensis is the most widespread of the three species, while the distribution of L. truncatula displaysa sporadic and limited pattern. The alien invader species L. columella was first reported from SouthAfrica in the early 1940’s but was so successful in its invasion of water-bodies in South Africa thatit is currently considered the third most widespread freshwater snail in the country. Lymnaea truncatula was the only one of the three species not recovered from all 14 water-body types represented in the database. The largest number of samples of L. truncatula by far, was yielded by marshes while the largest number of samples of the other two species was collected in rivers, streams and dams. The highest percentage occurrence of all three species was in habitats in which the water conditions were described as permanent, standing, fresh and clear. Although the highest percentage of samples of all three species was reported from loci that fell within the interval ranging from 16-20°C, a significant number of samples of L. truncatula came from loci falling with in the 11-15°C interval. In view of the fact that Lymnaea species are well known as intermediate hosts for liver fluke in South Africa and elsewhere in the world, the widespread occurrence of these snails could have considerable health and economic consequences. Lymnaea natalenis is the most important and probably the only intermediate host of Fasciola gigantica, the most common liver fluke in Africa but F. gigantica has been reliably reported only from Lesotho where its traditional intermediate host, L. truncatula is widespread. However, the epidemiology of fasciolosis in South Africa has been complicated by the invasion of many water-bodies by L. columella because this species has proved to be a successful host for F. hepatica where it had been introduced elsewhere in the world. To our knowledge its role in South Africa in this respect has not yet been evaluated. Due to the fact that no statistics are available in print, the results of positive serological tests on cattle herds all over South Africa were used to compile a map depicting the possible occurrence of Fasciola species in livestock in this country. Although human infections with Fasciola in Africa was considered as very rare in 1975 the situation has changed. It is considered an underrated and underreported disease in humans in Ethiopia and in Egypt an increase in cases of fasciolosis and prevalence’s as high as 12.8% in humans have also recently been reported. To our knowledge the only cases of human fasciolosis reported in literature for South Africa were from northern KwaZulu-Natal where F. hepatica infections were found in 22 out of 7 569 school children examined in 1981. Efforts to obtain recent statisticson human infections from various persons and authorities were totally unsuccessful. In view of statistics available for elsewhere in the world, it would be unwise to assume that no problems exist in this regard in South Africa. The number of people suffering from fasciolosis was already estimated at 2.4 million in 61 countries in 1995 and another 180 million at risk of becoming infected, with the highest prevalence’s reported from Bolivia, China, Ecuador, Egypt, France, Iran, Peru and Portugal. The results of recent serological assays for the detection of fasciolosis in cattle herds in selected areas in South Africa indicated positive cases from localities that closely correspond to the geographical distribution of the three Lymnaea species in this country. According to reports in the literature, the high prevalence of fasciolosis in livestock in the highlands of Ethiopia couldhave serious health implications for people in the area because they have to use the same water resources. In many rural areas in South Africa local populations also have no other options than to share natural water resources with their livestock. In most instances these water bodies harbour at least one of the Lymnaea species which can maintain the life cycle of fasciola. Under such conditions residents could daily be exposed to the risk of becoming infected. It is a matter of concern that epidemiological research with regard to human fasciolosis is such aneglected subject in South Africa. In our opinion epidemiological surveys should be conducted to determine the prevalence of human fasciolosis in specific areas which could be selected on the basis of using the geographical distribution of the three Linnaean species as guidelines. Efforts should also be made to conduct surveys to update the geographical distribution of the snail intermediate hosts and awareness programmes should be launched in rural areas at risk.

scholarly journals Distribution and habitats of Lymnaea natalensis, snail intermediate host of the liver fluke Fasciola gigantica, in South Africa

2001 ◽  
Vol 20 (2) ◽  
pp. 56-71
Author(s):  
Editorial Office
Keyword(s):  
South Africa ◽  
Intermediate Host ◽  
Geographical Distribution ◽  
Liver Fluke ◽  
Economic Factor ◽  
Freshwater Snail ◽  
Fasciola Gigantica ◽  
Snail Intermediate Host ◽  
Planning And Construction ◽  
Lymnaea Natalensis

This paper focuses on the geographical distribution and the habitats of Lymnaea natalensis, the snail intermediate host of the liver fluke, Fasciola gigantica, as reflected by the collection sites of its 4 552 samples currently on record in the National Freshwater Snail Collection (NFSC) of South Africa. Although this species was represented in a variety of waterbodies, the majority of samples(±70%)came from rivers, brooks and dams and in 70.8% of the cases the water was described as permanent and in 71.8% as slow flowing or standing. The results of life-table studies conducted by various authors indicated that temperature should be a relatively unimportant factor in determining its geographical distribution, but that the availability of permanent water should be decisive for its presence in a given habitat. These results are in agreement with the finding that only 7.5% of the samples of this species in the NFSC were collected in habitats which were described as seasonal. Furthermore, it gives a logical explanation for the sporadic occurrence, or total absence of this species in the more arid regions of South Africa. Water impoundments and irrigation networks contribute to a large extent towards creating perennial habitats which would be suitable for L. natalensis. As intermediate host for one of the liver fluke species which already is an economic factor in South Africa, this certainly is an aspect which ought to be reckoned within the planning and construction of new irrigation schemes.

scholarly journals Verspreiding en habitats van Lymnaea natalensis, tussengasheerslak van die lewerbot Fasciola gigantica, in Suid-Afrika

2001 ◽  
Vol 20 (2) ◽  
pp. 49-53 ◽  
Author(s):  
K. N. De Kock ◽  
C. T. Wolmarans ◽  
H. D. Strauss ◽  
M. Killian
Keyword(s):  
South Africa ◽  
Intermediate Host ◽  
Geographical Distribution ◽  
Liver Fluke ◽  
Economic Factor ◽  
Freshwater Snail ◽  
Fasciola Gigantica ◽  
Snail Intermediate Host ◽  
Planning And Construction ◽  
Lymnaea Natalensis

Hierdie artikel fokus op die geografiese verspreiding en die habitats van Lymnaea natalensis, die slaktussengasheer van die lewerbot, Fasciola gigantica, soos gereflekteer deur die vindplekke van sy 4 552 monsters wat tans in die Nasionale Varswaterslakversameling (NVV) van Suid-Afrika op rekord is. Alhoewel hierdie spesie in’n verskeidenheid van waterliggame aangetref is, was die meerderheid van die monsters (±70%) afkomstig vanuit riviere, spruite en damme en is die water in 70.8% van die gevalle as standhoudend en in 71.8% van die gevalle as stadigvloeiend, of staande beskryf.  Die resultate van lewenstabeleksperimente deur verskeie outeurs het daarop gedui dat temperatuur ’n minder belangrike bepalende faktor in sy geografiese verspreiding blyk te wees, maar dat die beskikbaarheid van standhoudende water deurslaggewend vir sy voorkoms in ’n gegewe habitat mag wees. Hierdie resultate strook met die bevinding dat slegs 7.5% van die monsters van hierdie spesie in die NVV in habitats wat as seisoenaal beskryf is, versamel is. Verder bied dit’n logiese verklaring vir die sporadiese voorkoms, of totale afwesigheid van hierdie spesie in die droër streke van Suid-Afrika.  Opgaardamme en besproeiingsnetwerke dra grootliks by tot die skepping van permanente habitats wat geskik sou wees vir L. natalensis.  As tussengasheer vir een van die lewerbotspesies wat reeds ’n ekonomiese faktor in Suid-Afrika is, is dit ’n aspek waarmee beslis rekening gehou behoort te word in die beplanning en konstruksie van nuwe besproeiingsprojekte.AbstractDistribution and habitats of Lymnaea natalensis, snail intermediate host of the liver fluke Fasciola gigantica, in South Africa This paper focuses on the geographical distribution and the habitats of Lymnaea natalensis, the snail intermediate host of the liver fluke, Fasciola gigantica, as reflected by the collection sites of its 4 552 samples currently on record in the National Freshwater Snail Collection (NFSC) of South Africa.  Although this species was represented in a variety of waterbodies, the majority of samples (±70%) came from rivers, brooks and dams and in 70.8% of the cases the water was described as permanent and in 71.8% as slow flowing or standing.  The results of life-table studies conducted by various authors indicated that temperature should be a relatively unimportant factor in determining its geographical distribution, but that the availability of permanent water should be decisive for its presence in a given habitat.  These results are in agreement with the finding that only 7.5% of the samples of this species in the NFSC were collected in habitats which were described as seasonal.  Furthermore, it gives a logical explanation for the sporadic occurrence, or total absence of this species in the more arid regions of South Africa. Water impoundments and irrigation networks contribute to a large extent towards creating perennial habitats which would be suitable for L. natalensis.  As intermediate host for one of the liver fluke species which already is an economic factor in South Africa, this certainly is an aspect which ought to be reckoned with in the planning and construction  of new irrigation schemes.

scholarly journals Distribution and habitats of Unio caffer Krauss, 1848 (Bivalvia: Unionoida: Unionidae) in South Africa based on the records in the database of the National Freshwater Snail Collection

2010 ◽  
Vol 29 (4) ◽  
pp. 173-185 ◽  
Author(s):  
K. N. De Kock ◽  
C. T. Wolmarans
Keyword(s):  
South Africa ◽  
Geographical Distribution ◽  
Water Body ◽  
Conservation Status ◽  
Freshwater Snail ◽  
Water Bodies ◽  
Valid Species ◽  
Local Health ◽  
Western Cape ◽  
Freshwater Molluscs

The distribution of the Unionoida is almost cosmopolitan and reaches its greatest diversity in North America with 860 currently recognized valid species. Two genera of the family Unionidae, Unio and Coelatura, comprising four species, occur in South Africa. This article focuses on the distribution and habitats of Unio caffer Krauss, 1848 based on the records in the database of the National Freshwater Snail Collection (NFSC) of South Africa. This bivalve is considered to be endemic to South Africa and although it was sporadically reported from elsewhere in South Africa, the Western Cape is the only province from which no samples are on record in the database of the NFSC. The majority of the 58 samples on record was recovered from rivers (32.8%) and dams (20.7%) and from water conditions described as perennial, clear and fresh and 22 of the samples were collected in water bodies with a predominantly sandy substratum. A temperature index calculated for this species ranked it in fi fth position of the 12 bivalve species represented in the database on account of its association with low climatic temperatures. An integrated decision-tree analysis indicated that temperature, substratum and water bodies per se were the most important factors of those investigated that played a signifi cant role in establishing the geographical distribution of this species in South Africa. Comprehensive surveys for freshwater molluscs conducted by state and local health authorities were discontinued during the eighties of the previous century and the majority of sampling sites have not been revisited since. Therefore hardly any recent data pertaining to the conservation status and species diversity of the mollusc fauna of South Africa are available. However, during relatively recent surveys conducted by the authors at three previously positive sites for U. caffer no specimens of this species could be recovered and it is also reported in literature that its range in the south-western Cape has decreased in recent years. With regard to its conservation status, the above findings seem to suggest that U. caffer should at least be considered as vulnerable – if not endangered – as reported for some related species elsewhere in the world. Although speculative, several reasons are suggested to explain the global phenomenon of decline in freshwater bivalves. These include, amongst others, construction of impoundments, introduction of alien species, wetland drainage and canalization and pollution. However, the unique lifecycle of the Unionoida could also play an important role in this respect due to the fact that their larval stages are obligatory parasites on fish. These bivalves are therefore dependent on fish for their survival and dispersal and without their host fish populations will disappear. To sustain a viable population a water body should therefore be suitable not only for the bivalves themselves but also for their host fi sh. As mentioned earlier, the majority of samples of U. caffer were recovered from dams and rivers, water body types both under pressure of over exploitation and pollution. It is therefore recommended that thorough surveys should be planned and conducted in specific areas which could be selected with the documented geographical distribution in the database of the NFSC as guideline. A comparison of the results of such surveys with the data in the database of the NFSC could make a considerable contribution towards assessing the current conservation status and diversity of the freshwater molluscs of South Africa.

scholarly journals Distribution and habitats of Bulinus tropicus, snail intermediate host of the conical fluke Calicophoron microbothrium, in South Africa

2002 ◽  
Vol 21 (4) ◽  
pp. 114-120
Author(s):  
K. N. De Kock ◽  
C. T. Wolmarans ◽  
M. Bornman ◽  
D. C. Maree
Keyword(s):  
South Africa ◽  
Intermediate Host ◽  
Geographical Distribution ◽  
Freshwater Snail ◽  
Wide Distribution ◽  
Limiting Factor ◽  
Snail Species ◽  
Rural Settlements ◽  
Economic Implications ◽  
Snail Intermediate Host

This paper focuses on the geographical distribution and the habitats of Bulinus tropicus, the snail intermediate host of the conical fluke, Calicophoron microbothrium. Bulinus tropicus is the freshwater snail species with the most extensive geographical distribution, as reflected by the collection sites of the 7 992 samples currently on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. The presence of this species was noted by collectors in a total of 14 different types of waterbodies, however, the largest number of samples was collected in dams and brooks and in habitats of which the water was described as standing, clear and fresh. The effect size was calculated for each variable separately to determine its importance in governing the distribution of this species. The data in the database were further processed and adapted to construct an integrated decision tree. This is a statistical model allowing the selection of those variables which can maximally discriminate between the frequency of occurrence of a given species and all other species in the database under specific conditions. The success of B. tropicus, as reflected by its extensive geographical distribution, can most probably be ascribed to the circumstance that population dynamic studies by various authors have shown, without any doubt, that it is highly r-selected and that it additionally has the ability to survive conditions of drought for elatively long periods. It does however, appear as if its limited tolerance to water with a relatively low conductivity could possibly be a limiting factor for its colonisation of specific areas in South Africa. As intermediate host of C. microbothrium which causes paramphistomosis in domestic stock and sometimes can lead to great losses, the wide distribution of B. tropicus has economic implications, especially for residents of informal, rural settlements whose livestock traditionally forms an integral part of their daily existence.

scholarly journals Cercariae developing in Lymnaea natalensis Krauss, 1848 collected in the vicinity of Pretoria, Gauteng Province, South Africa

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
E.B.E. Moema ◽  
P.H. King ◽  
C. Baker
Keyword(s):  
South Africa ◽  
Freshwater Snail ◽  
Freshwater Snails ◽  
Parasitic Diseases ◽  
Intermediate Hosts ◽  
Gauteng Province ◽  
The Family ◽  
Different Types ◽  
Lymnaea Natalensis ◽  
Scanning Electron

Freshwater snails are known to serve as first intermediate hosts for various parasitic diseases such as schistosomosis and fasciolosis. Snails were collected on several occasions in the proximity of Pretoria, South Africa and their cercarial sheddings were studied. This article describes three different types of cercariae shed by the freshwater snail, Lymnaea natalensis, viz. a fork-tailed cercaria of a Trichobilharzia sp., an avian parasite belonging to the family Schistosomatidae, an echinostomatid cercaria of the family Echinostomatidae, also avian parasites and a xiphidiocercaria of the family Plagiorchiidae which parasitise avians and amphibians. The morphology of these cercariae was studied by light and scanning electron microscopy.

RESEARCH FINDINGS INFECTION FASCIOLIASIS BY TECHNICAL ENZYMES LINKED IMMUNOSORBENT (ELISA)

2013 ◽  
pp. 44-49
Author(s):  
Van Phu Dang ◽  
Thang Tran ◽  
Chi Thanh Nguyen ◽  
Thi Phuong Nhi Tran ◽  
Viet Duy Nguyen ◽  
...  
Keyword(s):  
Aquatic Plants ◽  
Rural Areas ◽  
Liver Fluke ◽  
Central Hospital ◽  
Suspected Infection ◽  
The World ◽  
Research Findings ◽  
Fluke Infection ◽  
Common Liver Fluke ◽  
Liver Fluke Infection

Introduce: Fascioliasis is an infection common in animals,particularly sheep and cattle, and is widespread around the world. The disease can be transmitted through food to Humans where it affects the liver. It is also known as “common liver fluke infection”. Material and method: Include 326 person with suspected infection of fasciolasis, and recived ELISA from 4/2012 to 6/2013 at Hue Central Hospital. Result: The rate of ELISA positive liver for 31.3%, men 24.4%, women 38.3%, rural areas accounted for 36.8%, Farmer group 36.2%. Conclusion: Prevalence of Fasciolisis with symptoms suggestive in clinically is 31.3%. Main source of contamination due to people eating aquatic plants. Key words: Fascioliasis, ELISA

Fusarium oxysporum f. sp. lycopersici. [Descriptions of Fungi and Bacteria].

1992 ◽  
Author(s):  
D. Brayford
Keyword(s):  
South Africa ◽  
Great Britain ◽  
Lycopersicon Esculentum ◽  
Fusarium Oxysporum ◽  
Geographical Distribution ◽  
Tomato Fruit ◽  
Fruit Rot ◽  
Vascular Wilt ◽  
Planting Material ◽  
The World

Abstract A description is provided for Fusarium oxysporum f. sp. lycopersici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lycopersicon esculentum (tomato). May also infect other species of Lycopersicon. DISEASE: Vascular wilt. The fungus may also cause tomato fruit rot. GEOGRAPHICAL DISTRIBUTION: Widespread in tomato growing regions of the world. Africa: Kenya, Morocco, Nigeria, Republic of South Africa, Senegal, Tanzania, Tunisia. America: Argentina, Brazil, Canada, Cuba, Mexico, USA. Asia: China, India, Iran, Iraq, Israel, Japan, Korea, Pakistan. Australasia: Australia. Europe: Albania, Belgium, Bulgaria, France, Germany, Great Britain, Italy, The Netherlands, Spain, USSR. TRANSMISSION: The fungus is soil borne and may also be transmitted by seed (58, 3447; 67, 1486), planting material and locally by water flow.

Distribution of Snails serving as Intermediate Hosts of Flukes in South Africa

Parasitology ◽  
1924 ◽  
Vol 16 (1) ◽  
pp. 67-68 ◽  
Author(s):  
F. G. Cawston
Keyword(s):  
South Africa ◽  
Microscopic Examination ◽  
Freshwater Snail ◽  
Freshwater Snails ◽  
Intermediate Hosts ◽  
Water Lily ◽  
Cato Manor ◽  
New Localities

When, in 1917–18, I made a microscopic examination of freshwater snails at Potchefstroom, Transvaal, I found 10 per cent, of the examples of Isidora schackoi Jickeli infested with eye-spotted cercariae which Dr E. C. Faust recognised as amphistomes. Some shells which I collected from the same pools and considered to be immature examples of Isidora schackoi have been identified as Sericima. It is possible that the two species are identical. I found Isidora forskali at Cato Manor, outside Durban, infested with amphistomes, and confirmed this observation by isolating similar cercariae from the same freshwater snail on the Umgeni flats. I have obtained examples of Isidora forskali from Amanzimtoti, Isipingo, Clairwood, Umhl-a-tazana, Cato Manor, Inchanga station, Umgeni, Tongaat, Nonoti, Umzindusi, at Pietermarizburg, Lourenço Marques and Beira. These places constitute several new localities for the species and no Isidorae had previously been recorded from Beira. This mollusc is common in small shallow spruits and is often attached to small plants or water-lily leaves. It is seldom more than 10 mm. in length.

scholarly journals Distribution and habitats of the snail Lymnaea truncatula, intermediate host of the liver fluke Fasciola hepatica, in South Africa

2003 ◽  
Vol 74 (4) ◽  
Author(s):  
K.N. De Kock ◽  
C.T. Wolmarans ◽  
M. Bornman
Keyword(s):  
South Africa ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Decisive Role ◽  
Freshwater Snail ◽  
Snail Host ◽  
Annual Rainfall ◽  
North West ◽  
Lymnaea Truncatula ◽  
Mollusc Species

This paper focuses on the geographical distribution and habitats of Lymnaea truncatula, the intermediate, snail host of the liver fluke, Fasciola hepatica, as reflected by the 723 samples in the database of the National Freshwater Snail Collection, Potchefstroom, South Africa. The 221 different loci (1/16-degree squares) on record reflect an extensive but discontinuous distribution, except in Lesotho and in parts of the Mpumalanga, Gauteng and North West provinces of South Africa. Although recorded from 12 different types of waterbody, it was mostly (42.0 %) recovered from swamps. Most samples (45.8 %) were collected in habitats with slow-flowing water. A muddy substratum was recorded for 62.5 % of the samples. Most samples (86.3 %) were collected in habitats with a mean annual air temperature of 10-20 o C, and more than 69 % came from localities with a mean annual rainfall of 600-900mm. An integrated decision tree constructed from the data indicated that temperature and types of waterbody play a decisive role in determining the presence of L. truncatula in a given area. A temperature index calculated for all mollusc species ranked L. truncatula second in a total of 53 species according to its association with low temperatures. It remains to be established whether its distribution is indeed discontinuous, and whether its preference for a particular habitat, amphibious habits and ability to aestivate could have resulted in some populations having been overlooked during surveys.

Liver fluke infections

2020 ◽  
pp. 1551-1558
Author(s):  
Ross H. Andrews ◽  
Narong Khuntikeo ◽  
Paiboon Sithithaworn ◽  
Trevor N. Petney
Keyword(s):  
Liver Fluke ◽  
Cyprinid Fish ◽  
Intermediate Hosts ◽  
Mild Disease ◽  
The World ◽  
Fluke Infection ◽  
Duct Cancer ◽  
Cooked Food ◽  
Liver Flukes ◽  
Liver Fluke Infection

Liver flukes, otherwise known as trematodes, are leaf-like hermaphroditic flatworms. In certain parts of the world, the hepatobiliary system of humans is commonly infected by flukes of the genera Clonorchis and Opisthorchis and occasionally by other species. Humans acquire liver fluke infection by the ingestion of viable metacercariae that are found in second intermediate hosts through raw or partially cooked food, predominately cyprinid fish. These infections are usually diagnosed by finding eggs in the faeces. The diseases caused by liver flukes range from asymptomatic, mild disease to fatal bile duct cancer. Currently the drugs of choice for treatment of liver fluke infection are praziquantel and triclabendazole.

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