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Search Results: 1 - 10 of 174025 matches for " KN de Kock "
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Distribution and habitats of Bulinus depressus and possible role as intermediate host of economically important helminth parasites in South Africa
KN de Kock, CT Wolmarans
Water SA , 2005,
Abstract: This article documents the large-scale spatial distribution and ecological descriptors of associated habitats of Bulinus depressus by analysis of samples taken from 552 collection sites on record in the database of the National Freshwater Snail Collection (NFSC) at the Potchefstroom Campus of the North-West University. This snail species is experimentally susceptible to Schistosoma margrebowiei, a helminth parasite of game animals and cattle and can possibly also exploit humans as definitive hosts. The 125 different loci (1/16 degree squares) on record reflect a geographical distribution that is largely limited to the central and western part of the Limpopo Province and westwards down the basins of the Vaal and Orange Rivers. Details of each habitat as described by collectors during surveys, as well as altitude and mean annual air temperature and rainfall for each locality, were processed and chi-square and effect size values calculated. A decision tree constructed from all the available data indicated that temperature and altitude, followed by the type of water-body, seemed to be the more important factors that significantly influenced the distribution of this species in South Africa. The possible role of this species as intermediate host of economically important helminth species is briefly looked at and the urgent need to update the geographical distribution of host snails is emphasised. It is recommended that efforts be made to determine the exact role of B. depressus in the epidemiology of economically important helminth parasites.
Distribution and habitats of Melanoides tuberculata (Müller, 1774) and M. victoriae (Dohrn, 1865) (Mollusca: Prosobranchia: Thiaridae) in South Africa
KN de Kock, CT Wolmarans
Water SA , 2009,
Abstract: An account is given of the geographical distribution and habitats of Melanoides tuberculata (Müller, 1774) and M. victoriae (Dohrn, 1865) as reflected by the samples on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. About 30 species of Melanoides occur in Africa of which only M. tuberculata is widespread. Melanoides tuberculata is also indigenous to India and the south-east Asian mainland to northern Australia and was widespread in the present-day Sahara during the late Pleistocene-Holocene, but M. victoriae seems to be restricted to Southern Africa. Details of the habitats on record for each species, as well as mean altitude and mean annual air temperature and rainfall for each locality, were processed to determine chi-square and effect-size values. An integrated decision-tree analysis indicated that temperature, altitude and type of substratum were the most important factors of those investigated that played a significant role in establishing the geographical distribution of these species in South Africa. In view of the fact that M. tuberculata can serve as intermediate host for a number of trematode species elsewhere in the world, it is recommended that the ability of the 2 local Melanoides species to act as intermediate hosts should be investigated. Due to the fact that the majority of sites from which these species were recovered were not since revisited, it is recommended that efforts should be made to update their geographical distribution and the results compared with the data in the database. The conservation status of these 2 species and the possible influence of global warming and climatic changes on their geographical distribution are briefly discussed.
Distribution and habitats of the Bulinus africanus species group, snail intermediate hosts of Schistosoma haematobium and S. mattheei in South Africa
KN de Kock, CT Wolmarans
Water SA , 2005,
Abstract: As intermediate host of Schistosoma haematobium and S. mattheei, the Bulinus africanus group plays a major role in the transmission of urinary and bovine schistosomiasis, diseases that negatively affect the health status of millions of people and their livestock in South Africa. Bulinus spp. can also play a role in the transmission of cercarial dermatitis (swimmer's itch) caused by the immune reaction of incompatible hosts to the penetration of cercariae of non-human schistosomes. This can cause considerable discomfort to humans bathing in infested waters. This article focuses on the geographical distribution and habitats of this group as reflected by the samples taken from 2 930 collection sites on record in the database of the National Freshwater Snail Collection (NFSC) at the Potchefstroom Campus of the North-West University. The 414 different loci (1/16-degree squares) on record, reflect an extensive distribution from the western parts of the North- West to Gauteng, Mpumalanga, Limpopo and KwaZulu-Natal Provinces and the coastal areas of the Eastern Cape Province. Details of each habitat as described by collectors during surveys, as well as altitude and mean annual temperature and rainfall of each locality, were processed and chi-square and effect size values were calculated. A decision tree constructed from all the available data indicated that temperature and altitude, followed by the type of water-body, seemed to be the more important factors that had a significant influence on the distribution of this group in South Africa. The role of the B. africanus group in the transmission of schistosome species is briefly discussed and the urgent need for co-ordinated surveys to update the geographical distribution of host snails, as well as the schistosome parasites in South Africa, is stressed.
Distribution and habitats of Melanoides tuberculata (Müller, 1774) and M. victoriae (Dohrn, 1865) (Mollusca: Prosobranchia: Thiaridae) in South Africa
KN de Kock, CT Wolmarans
Water SA , 2009,
Abstract: An account is given of the geographical distribution and habitats of Melanoides tuberculata (Müller, 1774) and M. victoriae (Dohrn, 1865) as reflected by the samples on record in the database of the National Freshwater Snail Collection (NFSC) of South Africa. About 30 species of Melanoides occur in Africa of which only M. tuberculata is widespread. Melanoides tuberculata is also indigenous to India and the south-east Asian mainland to northern Australia and was widespread in the present-day Sahara during the late Pleistocene-Holocene, but M. victoriae seems to be restricted to Southern Africa. Details of the habitats on record for each species, as well as mean altitude and mean annual air temperature and rainfall for each locality, were processed to determine chi-square and effect-size values. An integrated decision-tree analysis indicated that temperature, altitude and type of substratum were the most important factors of those investigated that played a significant role in establishing the geographical distribution of these species in South Africa. In view of the fact that M. tuberculata can serve as intermediate host for a number of trematode species elsewhere in the world, it is recommended that the ability of the 2 local Melanoides species to act as intermediate hosts should be investigated. Due to the fact that the majority of sites from which these species were recovered were not since revisited, it is recommended that efforts should be made to update their geographical distribution and the results compared with the data in the database. The conservation status of these 2 species and the possible influence of global warming and climatic changes on their geographical distribution are briefly discussed.
Distribution and habitats of Biomphalaria pfeifferi, snail intermediate host of Schistosoma mansoni, in South Africa
KN De Kock, CT Wolmarans, M Bornman
Water SA , 2004,
Abstract: As intermediate host for Schistosoma mansoni, Biomphalaria pfeifferi plays a major role in the transmission of intestinal bilharziasis in the endemic areas of South Africa. This article focuses on the geographical distribution and habitats of this species, as reflected by the 1 639 samples on record in the database of the National Freshwater Snail Collection of South Africa. This snail is well represented in the Northern Province, Mpumalanga and the coastal areas of KwaZulu-Natal, that represent the bilharzia endemic areas of South Africa. Details of each habitat, as well as mean altitude and mean annual temperature and rainfall of each locality, were processed to determine chi-square and effect size values and to construct an integrated decision tree that makes a selection of those variables that could maximally discriminate between this snail and all the other species in the database. The results indicated that temperature and type of water-body are the major factors determining the distribution of B. pfeifferi in South Africa. These findings support the results of demographic studies reported by several authors that led them to the conclusion that B. pfeifferi does best under warm stable conditions. The importance of four isolated and persistent foci occurring further west than the western arm of its range of distribution and far removed from the bilharzia endemic areas, is discussed. Two of these localities are popular holiday resorts and the fact that specimens from both these localities showed a high compatibility with a local strain of S. mansoni is cause for concern. Water SA Vol.30(1): 29-36
Verspreiding en habitats van Ceratophallus natalensis (Mollusca: Planorbidae) in Suid-Afrika
K. N. de Kock
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2007, DOI: 10.4102/satnt.v26i2.128
Abstract: Hierdie artikel handel oor die geografiese verspreiding en habitats van Ceratophallus natalensis soos weerspie l deur die 1 797 monsters wat tans in die databasis van die Nasionale Varswater- slakversameling (NVWSV) opgeneem is. Hierdie spesie is in al 14 verskillende waterliggaamtipes wat in die databasis verteenwoordig word, aangetref. Die grootste getal monsters was afkomstig van damme, spruite en riviere. Habitats met standhoudende, stilstaande en varswater waarvan die substratum oorwegend uit modder bestaan het, was die beste verteenwoordig. Die resultate van ’n ge ntegreerde besluitnemingsboom- en effekgrootte-analise het getoon dat temperatuur, hoogte bo seevlak en waterliggame as sodanig, ’n deurslaggewende rol in die gedokumenteerde geografiese verspreiding van hierdie spesie in Suid-Afrika gespeel het. ’n Temperatuurindeks wat bereken is, het getoon dat C. natalensis ook goed toegerus is om habitats in die koeler streke van Suid-Afrika te bevolk. Gesien in die lig van die wye geografiese verspreiding van hierdie spesie in hierdie land en dat dit elders in Afrika bevind is dat dit serkarie van verskeie helmintspesies onder natuurlike toestande kan vrystel, word dit aanbeveel dat sy rol as tussengasheer in Suid-Afrika deeglik ondersoek behoort te word. Distribution and habitats of Ceratophallus natalensis (Mollusca: Planorbidae) in South Africa Species of the genus Ceratophallus are known only from some islands in the western Indian Ocean and Africa, where they occur in Eritrea and the area extending southwards and westwards into the Western Cape of South Africa. The most recent classification recognises nine species of this genus of which only two, namely Ceratophallus natalensis (Krauss) and Ceratophallus gibbonsi (Nelson) occur in South Africa. Although partially sympatric, C. gibbonsi is largely associated with a tropical climate and perennial water-bodies while C. natalensis is fairly common in cooler areas and are often found in ephemeral rain pools. This article focuses on the geographical distribution and habitats of C. natalensis, the most widespread species of the genus, as reflected by the data on record in the National Freshwater Snail Collection (NFSC). Details pertaining to the habitats of 1 797 samples of C. natalensis as recorded at the time of collection were extracted from the database of the NFSC. In view of the finding of Brown1 that C. natalensis and C. gibbonsi are partly sympatric, but that the latter is associated with fully tropical climatic areas, samples of Ceratophallus collected in loci ( 1 / 16 th square degrees) th
B. X. DE WET ESSAY: DIE HERDER EN DIE WOLF 'N VERGELYKING TUSSEN DIE KARAKTERS VAN AENEAS EN TURNUS
A. De Kock
Akroterion , 2012, DOI: 10.7445/47-0-113
Abstract: Die studente-essay wat as die beste beoordeel word uit dié wat voor 30 Junie in dievoorafgaande jaar vir beoordeling voorgelê word, word jaarliks in Akroteriongepubliseer. Die kompetisie word geborg deur die Klassieke Vereniging van Suid-Afrikaen alle voorgraadse studente mag deelneem. Honneursstudente mag in gelykgenommerdejare inskryf. Daar is ‘n prys van R250 verbonde aan hierdie essay wat vernoem is na dieSuid-Afrikaanse klassikus B X De Wet.
She Looks so Beautiful
Karen de Kock
Voices: A World Forum for Music Therapy , 2008,
Abstract: This article offers a story that illustrates how the medium of music is able to provide comfort, even in extreme cases of hopelessness, when all other efforts seem futile. I will relate how the creative act of music-making within an institutional setting, was able to provide comfort to a self-injurious female psychiatric client, who had been institutionalised all her life, to restore a sense of beauty and dignity which had been lost. The music that was created in the moment was also able to carry and support all the individuals who were creating it - even in the most desperate moments where those that were supposed to be "in command" were experiencing a sense of uncertainty. The story further demonstrates how a client, a care-worker and a therapist, three individuals from very diverse backgrounds and life circumstances, were able to transcend their different histories to come together and connect on a level which they have not been able to do outside the music therapy room.
Die invloed van gesondheidsopvoeding op die prevalensie van skistosoombesmettings by leerders in ’n skistosoom- endemiese gebied in die Limpopoprovinsie
Corrie Wolmarans,Kenné de Kock
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2008, DOI: 10.4102/satnt.v27i2.84
Abstract: In hierdie studie is geselekteerde direkte en indirekte onderrigmetodes ge valueer ten opsigte vanhulle potensiaal om die prevalensie van skistosoombesmettings by skoolgaande kinders, woonagtigin ’n landelike omgewing in ’n skistosoom-endemiese gebied, te verlaag. Twee direkte (poppekas enblaaibord) en drie indirekte (plakkaat, kennisgewingbord en onderrig via ouers of voogde)onderrigmetodes is ge valueer.Skistosoombesmette leerders is met behulp van parasitologiese metodes ge dentifiseer en aan ’nvraelys in hul moerdertaal onderwerp om onder andere op hoogte van hulle kennis ten opsigte vanskistosomose te kom en te bepaal hoe die infrastruktuur tot hulle beskikking wat water en sanitasiebetref, daar uitsien. Leerders is met behulp van plaaslike gesondheidspersoneel vir die siekte behandelen daarna op verskeie geleenthede in samewerking met plaaslike onderwysers aan die verskillendeonderrigmetodes blootgestel.’n Aansienlike toename in die leerders se kennis aangaande skistosomose is reeds na die tweedeonderrigsessie waargeneem. Ten spyte van die feit dat die leerders in ’n skistosoom-endemiesegebied woonagtig was, het slegs 2% die siekte met ’n natuurlike waterhabitat soos ’n rivier geassosieer.Daar is verder gevind dat relevante amptelike strukture soos klinieke, geneeshere en skole byna geenrol speel in die verskaffing van inligting van wat die siekte behels en hoe dit oorgedra word nie.Betekenisvolle afnames in die kumulatiewe prevalensie van besmetting het by al die groepe, wat aandie onderskeie onderrigmetodes blootgestel was gedurende die ondersoek, voorgekom, wanneer ditmet die kontrolewaarde waar die leerders geen onderrig ontvang het nie, vergelyk is. Statistiesevergelykings tussen die verskillende onderrigmetodes het getoon dat die poppekas, blaaibord enplakkaat die effektiefste was om die prevalensie te verlaag, terwyl die gebruik van ouers of voogdedie minste effektief was. Alhoewel die kumulatiewe prevalensie van besmetting by laasgenoemde metode ook betekenisvol van die kontrolegroep verskil het, was bykans 50% van die “leerkragte” naeen jaar nie meer betrokke nie en wil dit voorkom asof bemagtiging van plaaslike inwoners omskistosomose te help bekamp, soos in hierdie studie gepoog is, nie veel potensiaal inhou nie. The influence of health education on the prevalence of schist some infected learners in aschistosome endemic area in the Limpopo Province During this study selected direct and indirect educational methods were evaluated as a means of decreasing the prevalence of schist some infections in school children living in a schistosomeen
Verspreiding van Burnupia capensis (Walker, 1912) en Burnupia stenochorias (Melvill & Ponsonby, 1903) (Gastropoda: Ancylidae) in Suid-Afrika
Kenné de Kock,Corrie Wolmarans
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2009, DOI: 10.4102/satnt.v28i3.59
Abstract: Die voorkoms van verteenwoordigers van die Ancylidae in Suid-Afrika is reeds in 1848 gerapporteer. Die eerste omvattende studie van hierdie familie in Suid-Afrika is egter eers in 1923 gepubliseer. Alhoewel verskeie bydraes sedertdien gepubliseer is, is verskeie outeurs van mening dat bestaande kennis oor die Ancylidae steeds gebrekkig is en dat hersiening nie net op spesievlak nie maar ook op genus-vlak nodig is. Tans is daar 14 Burnupia spesies op rekord in die databasis van die Nasionale Varswaterslakversameling (NVWSV). Hierdie bydrae handel oor die geogra ese verspreiding en habitats van B. capensis en B. stenochorias die twee Ancylidae spesies waarvan die meeste versamelpunte in die databasis van die NVWSV op rekord is en wat ook die mees wydverspreide geogra ese verspreiding van hierdie familie vertoon. Alhoewel beide spesies in die meerderheid van die verskeidenheid van waterliggame wat in die databasis vermeld word, aangetref is, is die grootste getal monsters van albei in standhoudende riviere en spruite en op ’n klipperige substraat versamel. Albei spesies is nie gerapporteer uit die dro r streke van Suid-Afrika nie waarskynlik as gevolg van ’n beperkte vermo om desikkasie te kan oorleef in gebiede waar standhoudende habitats ’n uitsondering is. Resultate dui daarop dat hoogte bo seevlak en aard van die substraat ’n belangrike rol gespeel het in die daarstelling van hul gedokumenteerde geogra ese verspreiding soos weerspie l deur die rekords in die NVWSV. Min is oor die bewaringstatus van die Ancylidae van Suid-Afrika bekend, maar die karige inligting wat wel tot ons beskikking is, dui op rede tot kommer. Om sinvolle uitsprake oor die bewaringstatus en spesiediversiteit van die Mollusca van Suid-Afrika te kan maak, word aanbeveel dat van die versamelpunte op rekord weer besoek behoort te word waarna die resultate met die bestaande rekords in die databasis van die NVWSV vergelyk kan word. Distribution of Burnupia capensis (Walker, 1912) and Burnupia stenochorias (Melvill & Ponsonby, 1903) (Gastropoda: Ancylidae) in South Africa The presence of Ancylidae in South Africa was established as early as 1848 but the rst comprehensive study on this family was reported in 1923. This author came to the conclusion that extensive work still had to be done before it could be declared that knowledge pertaining to the South African representatives of this family could be considered as satisfactory. Another important contribution on South African Ancylidae was published in 1939. After a detailed morphological and histological study on Burnupia mooiens
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