Large epidemics of poliomyelitis spread across the world in the first half of the 20th century. However, polio incidence fell rapidly across the world following the introduction of the oral poliovirus vaccine (OPV). Since the introduction of immunisation with OPV, the vaccine had a remarkable track record of success, because the number of wild-type polio cases decreased from 350 000 to 500 and the number of polio endemic countries declined from 125 to 10. Thus, the global eradication of wild-type poliovirus (PV) seems a realistic goal for the foreseeable future. Despite its many advantages, one disadvantage of the OPV is the potential risk of revertants of the OPV strains, which may cause neurological complications in vaccine recipients and susceptible contacts. Immunocompetent persons excrete OPV strains for a limited period of time. In contrast, immunodeficient people may become chronically infected and excretion times as long as 10 years have been reported. As a consequence, in the last phase of polio eradication this group of people may serve as potential reservoirs for vaccine-derived polioviruses (VDPVs). Two cases of vaccine-associated paralytic poliomyelitis have been reported in human immunodeficiency virus (HIV)-positive children, although, presently there is no evidence for prolonged excretion of PV from patients with HIV and acquired immunodeficiency syndrome (AIDS). Highly evolved VDPVs have been isolated from sewage and river water even in the absence of cases of paralytic poliomyelitis. This study aimed to investigate the prevalence of PVs in sewage and river water as well as in stool specimens of HIV-positive children (including those with an AIDS indicator condition according to the Centers for Disease Control and Prevention classification). Secondly, the study investigated the occurrence of genomic mutations in these OPV isolates. A total of 49 PV vaccine strains were isolated from the sewage and river water, and 13 PV vaccine strains were detected in the stools of immunodeficient children. Two of the immunodeficient patients (vaccinated 15 months ago) tested positive for Sabin PVs type 1 and 3. Another immunodeficient patient (vaccinated 42 months ago) tested positive for Sabin PV type 1. The 5’untranslated and the VP1 regions in the genomes of the OPV isolates were partially sequenced. The majority of the OPV strains detected in the sewage and river water displayed >99% VP1 sequence identity to the original PV vaccine strains and were classified as “OPV-like viruses”. Two OPV isolates were identified as “suspected” VDPVs, since these isolates showed £99% VP1 sequence identity to the PV vaccine strains and had probably replicated in one or more people for 12 to 16 months since the administration of the initiating OPV dose. In contrast, three “suspected” immunodeficient VDPVs were identified in the stools of the immunodeficient children. All of the OPV-like and “suspected” VDPV isolates carried genomic mutations, which had been associated with reversion of the attenuated PV phenotypes to increased neurovirulence. The identification of OPV-like and “suspected” VDPVs in this study emphasised the fundamental importance regarding the control of health risks constituted by OPV vaccination, particularly with regard to immunodeficient individuals such as HIV-positive children, and the possible role of water in the transmission of potentially hazardous VDPVs. These research findings provided valuable data, concerning prolonged excretion of OPV strains by individuals with secondary immunodeficiency and this could have major implications for strategies aimed for the global post-polio eradication era. / Thesis (PhD (Medical Virology))--University of Pretoria, 2004. / Medical Virology / unrestricted

The rapid development and spread of bacterial resistance to antimicrobial drugs is an increasing threat to human and animal health. Information on the prevalence of bacterial resistance to specific antimicrobial agents in both humans and animals together with changes occurring over time, is required to understand the magnitude of the problem, to make decisions and to take actions that are based on risk assessment (3). The ultimate goal is to preserve the effectiveness of available antimicrobial drugs for the benefit of future generations of animals and humans. The emergence of resistance and the spread of resistant bacteria can be limited by implementing a veterinary antimicrobial drug policy, in which inter alia systematic monitoring and prudent use play essential parts (1). Testing the susceptibility of bacteria to antimicrobial drugs is fundamental to the study of resistance. Sensitivity testing serves two purposes: to provide reliable results to the prescriber of antimicrobial drugs and to monitor changes in susceptibility of microbial populations. Standardized methods are needed for surveillance in the national and international context and harmonization of methods to provide meaningful comparisons between individual centres and countries (1, 3). The objective of this study was to establish a repeatable, standardized laboratory procedure for monitoring the development of antimicrobial resistance in bacteria isolated from animals and food of animal origin in South Africa. The bacteria included in this study represented three different groups, namely zoonotic bacteria (Salmonella), indicator bacteria (Escherichia coli, Enterococcus faecalis, E. faecium) and veterinary pathogens (Mannheimia haemolytica). Thirty isolates of each organism were collected with the aim of standardizing the laboratory methodology for a future national veterinary surveillance programme. Susceptibility to 10 antimicrobial agents was determined by means of minimum inhibitory concentrations (MIC’s) using the microdilution method. The method according to the National Committee for Clinical Laboratory Standards was used as the standard. Susceptibility tests were repeated once for each individual organism. Quality control measures were included to ensure that accurate results were obtained. Repeatability was satisfactory as results from duplicate tests differed by only one twofold dilution. Multi-well plates prepared in-house for MIC determinations also yielded repeatable results after two months of storage at -70°C. Within this limited sample of bacteria, MIC results did not indicate meaningful resistance against any of the 10 selected antimicrobials. / Dissertation (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2001. / Veterinary Tropical Diseases / unrestricted

The aim of this thesis is to prove the lifting property of zero divisors, n-zero divisors, nilpotent elements and a criteria for the lifting of polynomially ideal elements in C*-algebras. Chapter 1 establishes the foundation on which the machinery to prove the lifting properties stated above rests upon. Chapter 2 proves the lifting of zero divisors in C*-algebras. The generalization of this problem to lifting n-zero divisors in C*-algebras requires the advent of the corona C*-algebra, a result of the school of non-commutative topology. The actual proof reduces the general case to the case of the corona of a non-unital _-unital C*-algebra. Chapter 3 proves the lifting of the property of a nilpotent element also by a reduction to the case of the corona of a non-unital _-unital C*-algebra. The case of the corona of a non-unital _-unital C*-algebra is proved via a lifting of a triangular form in the corona. Finally in Chapter 4, a criterion is established to determine exactly when the property of a polynomially ideal element can be lifted. It is also shown that due to topological obstructions, this is not true in any C*-algebra. / Dissertation (MSc (Mathematics and Applied Mathematics))--University of Pretoria, 2004. / Mathematics and Applied Mathematics / unrestricted

This research seeks to examine the experience of educators regarding the support they receive from their principals during the implementation process of OBE at secondary school level. The study thus intends to explore the reaction of educators towards OBE as a newly introduced approach in South Africa and the impact of managerial support to educators towards the implementation of OBE. This study is a case study of two secondary schools at Vuwani in Limpopo Province. The study uses the questionnaires, face-to-face interview and focus group interviews to collect data. Questionnaires were distributed randomly among teachers of the two schools. The principals of the two schools were interviewed. Few educators were engaged in a focus group interviews. Categories and themes were used to analyse the data. Educators were given two weeks to complete and return the questionnaires. Each principal was interviewed once for an hour. Focus group interviews were conducted once in each school for a period of two hours. Letters to the principals and the educators of the respective schools were written to seek permission and positive participation in the case study. Five major themes emerged from the study: 1. Management and leadership skills 2. Resources 3. Workshops and / or courses and / or In-service training 4. Problem solving skills 5. Communication and networking / Dissertation (MEd (Education Management))--University of Pretoria, 2004. / Education Management and Policy Studies / unrestricted

The aim of this study was to evaluate the microbial quality of ostrich carcases produced in a South African export-approved ostrich abattoir. Ninety surface samples were collected on 30 ostrich carcases at three processing points in the abattoir: post-flaying, post-evisceration and post-chilling. Carcase samples were evaluated for the Aerobic Plate Count (APC), Pseudomonas spp., Enterobacteriaceae, Staphylococcus aureus and for the presence of Escherichia coli and presumptive Salmonella spp. One hundred isolates obtained from the APC were identified. The mean log CFU/cm2 and standard deviations for surface counts at post-flaying, post-evisceration and post-chilling processing points respectively were: 4.32 ±0.62, 4.21 ±0.63 and 4.57 ±0.48 for the APC; 2.82 ±1.65, 2.86 ±1.53 and 3.75 ±0.94 for Pseudomonas spp.; 2.89 ±0.78, 2.90 ±0.53 and 2.38 ±0.67 for S. aureus and 2.55 ±1.53, 2.78 ±1.31 and 2.73 ±1.46 for Enterobacteriaceae. No significant differences were detected between the mean log counts of the post-flaying and post-evisceration processing points for the above-mentioned bacterial counts. However, statistically significant differences were detected between the mean log CFU/cm2 counts for post-flaying and post-chilling and between the counts for the post-evisceration and the post-chilling processing points for the APC, Pseudomonas spp. and S. aureus. The trend was towards a marginal increase for the APC, and a negligible decrease for S. aureus counts obtained on samples collected post-chilling. However, there was an increase of practical significance for Pseudomonas spp. counts obtained post-chilling. Seventeen out of 90 (18.8%) samples were positive for E. coli in terms of samples collected and 13 out of 30 (43%) in terms of carcases sampled. Log CFU/cm2 counts for E. coli positive samples ranged from 1.0 to 3.79, with a mean log count of 2.15. Most of the samples, which were positive for E. coli were collected post-evisceration. The prevalence rate for presumptive Salmonella spp. on both Brilliant Green Agar and Xylose Lysine Desoxycolate Agar was 15.5% in terms of samples collected and 23.3% in terms of carcases sampled. Most of the positive samples were collected post-evisceration. The proportional distribution of one hundred (100) bacterial isolates identified was Enterobacteriaceae: 57%, Acinetobacter spp.: 24 %, Pseudomonas spp.: 11%, Aeromonas spp.: 3%, Micrococcus spp.: 3%, Staphylococcus spp.: 1% and yeasts: 1%. Enterobacteriaceae were the predominant bacteria in terms of the total number of isolates identified per processing point and for the whole study. / Dissertation (MMedVet (Hyg))--University of Pretoria, 2001. / Paraclinical Sciences / unrestricted

When consumers with limited product related consumer socialization migrate to more affluent communities and adopt new life styles later in life, they have to deal with a choice explosion that manifests as the paradox of progress and creates fertile ground for exploitation in the market place. Limited evidence could be found of how inexperienced consumers judge the quality of products as an indication of product reliability. This research was part of a larger research project that focused on major household appliances as a desirable commodity in modern households. This part of the project specifically aimed to identify the indicators (extrinsic factors) that are used to discriminate the quality of appliances during pre purchase evaluation. It was hypothesized that limited consumer socialization may result in a dependence on hedonics/ surrogate indicators of quality to compromise for the absence of appropriate product knowledge and personal product experience. A positivistic orientated research project that implemented a combination of qualitative and quantitative data collection techniques was designed to determine the quality judgment of major household appliances of more mature, previously deprived consumers in a specific geographical area. Experience with electricity and ownership of appliances were used to identify and recruit suitable individuals for participation. Supportive theory for this research included the theory of consumer socialization including product related consumer socialization, as well as the basic theory of consumer decision-making as it applies to quality judgment of major household appliances during pre-purchase evaluation. The inexperience of consumers in this part of the project was confirmed by their limited experience with electricity in their own households and limited ownership of appliances over time. A lamentable discrepancy was found between the anticipated and the reported service life figures for a list of 13 appliances. Although replacement purchases may be influenced by socio-economic variables, product characteristics and time factors, an upsetting low average service life for major appliances was calculated. Premature replacements could signify several problems e.g. irresponsible choice behaviour; poor after sales service, ignorance in terms of maintenance and care. Inexperienced consumers may for example also have unrealistic expectations. In terms of the criteria that are used to discriminate quality, BRAND NAME is apparently relied on strongly by all consumers, irrespective of their experience and socio economic status, which confirmed Dawar and Parker’s (1994) view of the existence of criteria of so-called “universal importance”. The inexperienced consumers in this part of the project revealed a significant higher reliance on surrogate indicators of quality such as PRICE, GUARANTEE and ADVERTISING. In terms of the product knowledge test that was included, the mean score for the sample was calculated to give an indication of participants’ potential to conclude informed buyer decisions in terms of knowledge of certain basic functional and performance attributes of appliances. Inexperienced consumers’ score in terms of product knowledge was alarmingly low. This confirms the theory of product related consumer socialization that proposes limited product knowledge with limited product related experience. Findings revealed a remarkable incongruity with respect to participants’ personal rating of the importance of quality in terms of the evaluation of household appliances and their apparent ability to do so. Only 3.2% of the older inexperienced consumers indicated quality per se to be of LITTLE or NO IMPORTANCE. The rest regarded it as very IMPORTANT or VERY IMPORTANT. When confronted with specific questions and tasks relating to product evaluation and quality judgment, the participants could not convince that they had the relevant product knowledge to discriminate quality in order to conclude informed, responsible buyer decisions with respect to major household appliances. In terms of the larger project, reliance on surrogate indicators during quality judgment manifested stronger among the inexperienced consumer groups. Findings also support Erdem et al (1999) who reported that materialistic values of aspirational groups generally result in dominance of social factors during product evaluation. / Dissertation (M (Consumer Science))--University of Pretoria, 2005. / Consumer Science / unrestricted

Fifteen middle-aged to older, overweight cats were investigated to rule out hyperadrenocorticism as a cause of their weight problem, using two different protocols for the adrenocorticotrophic hormone (ACTH) stimulation test. The cats received intravenous synthetic ACTH (tetracosactrin) at a dose of 125 µg initially and then, between 2 and 3 weeks later, a second test was performed using a dose of 250 µg intravenously. The peak of the mean serum cortisol concentrations taken at all time points, occurred at 60 minutes following the 125 µg dose and at 120 minutes following the 250 µg dose. There was no statistically significant difference between the cortisol peaks attained using either dose of tetracosactrin. There was, however, a significantly higher serum cortisol concentration attained after the higher dose at the 180 minutes time point, indicating a more prolonged response, when compared with the lower dose. The mean basal cortisol concentration was 203 nmol/l (range 81 – 354 nmol/l). The cats were followed up for one year after the initial investigations. Urine obtained one year later in the cats’ home environment, showed a mean urinary cortisol/creatinine ratio (UCCR) of 3.3 x 10 -6 (range 0.85 - 8.67 x 10 -6). A mean weight loss of 6 per cent was achieved over the period of the study. The weight loss, lack of development of clinical signs and the normal UCCR’s confirm that none of these cats had gone on to develop hyperadrenocorticism. / Dissertation (MMedVet (Med))--University of Pretoria, 2001. / Companion Animal Clinical Studies / unrestricted

Feline babesiosis is caused by the small intra-erythrocytic haemoprotozoan parasite, Babesia felis. Only in South Africa does it cause a significant clinical disease among domestic cats. A study was undertaken to further describe signalment and clinico-pathological changes and to identify concurrent infections. Fifty-six cats with naturally occurring B. felis infection, presented to private veterinarians for examination and treatment, were studied. An age predisposition seemed to be present, as most affected cats were young adults of less than three years of age. Although no breed or sex predisposition was evident, Siamese cats seemed to be over-represented amongst purebred cats. Typical clinical signs included anorexia, listlessness and anaemia. Less common signs included icterus, weakness, weight loss, constipation and pica. Feline babesiosis was diagnosed by identification of parasites on stained, thin blood smears. Parasitaemias were variable and ranged between very low (0.3%) and extremely high (42.3%). A strong correlation existed between central and peripheral parasitaemias, indicating that sequestration does not occur. Macrocytic, hypochromic, regenerative anaemia was the most consistent haematological finding; this became quite severe in advanced cases of disease. The anaemia was further classified as haemolytic, presumably resulting from both intravascular and extravascular erythrocyte destruction. Almost half the cats (43%) were not anaemic. No characteristic changes were seen in total or differential leukocyte counts; when abnormal values were present they were often accompanied by concurrent illness or infection. Thrombocyte counts were variable and thrombocytopaenia was an inconsistent finding. In-saline agglutination tests were positive in a number of cases, indicating that secondary immune-mediated haemolytic anaemia could also be a feature of this disease. The most remarkable clinico-pathological changes were elevation of hepatic cytosol enzyme activities and total bilirubin concentrations. Serum alanine transaminase was significantly elevated in the majority of cases, whereas alkaline phosphatase and gamma glutamyltransferase were generally within normal limits. This provides evidence of primary hepatocellular injury or inflammation in feline babesiosis. The hyperbilirubinaemia was most likely a result of haemolysis, but secondary hepatocellular injury was probably an additional contributing factor. No characteristic changes in renal parameters were observed and serum urea and creatinine levels were mostly within normal limits, indicating that gross renal damage was not a consistent feature of the disease. No characteristic pattern of changes in serum electrolytes (sodium and potassium) was seen, although a variety of electrolyte disturbances occurred in a number of cases. Serum protein values were mostly normal, but elevations were seen in some cases. Hyperalbuminaemia was considered indicative of patient dehydration. Polyclonal gammopathies were observed in all cats with hyperglobulinaemia and were ascribed to a combination of acute- and chronic-phase proteins produced in response to the Babesia antigens. Concurrent infections with Haemobartonella felis, feline leukemia virus and/or feline immunodeficiency virus were identified in a number of cats in this study and seemed to have profound effects on response to treatment and outcome of the disease. / Dissertation (MMedVet (Med))--University of Pretoria, 2001. / Companion Animal Clinical Studies / unrestricted

Effective recruitment&selection is of cardinal importance to any organisation, because it is a very expensive process and recruiting the wrong applicant can have a large cost implication for the organisation. Effective recruitment and selection also decrease staff turnover and increases productivity. To be able to give good customer service or deliver a good product, it is important for any organisation to recruit motivated, loyal and customer oriented employees. This starts by recruiting the most suitable candidate for the vacant position. Recruitment is the process of obtaining the most suitable candidates for a specific position. The selection process follows after recruitment. It is done by means of pre-selection, interviewing, testing&assessment as well as confirmation of references. The applicant forms its first impression of the organisation during the recruitment and selection process. This image can either be positive or negative and unrealistic expectations could also be formed by the applicant that can lead to conflict during his/her period of employment at the organisation. The process does not stop with the placement of the most suitable candidate. The newly appointed employee has to go through orientation and also receives the necessary training and development to be successful in the appointed position. According to the Labour Relations Act of 1956, employers had free reign with regards to the steps followed in the recruitment and selection process. There were no restrictions with regards to the inclusion of candidates in the recruitment and selection process. After the passing of the new Labour Relations Act of 1995, all employers had to revisit their recruitment and selection process. More questions arose, for instance : “Is this reasonable labour practice ?” and “When is it discrimination ?”. After the elections in 1994, aspects like affirmative action became a strong focus for all employers. Recruitment and selection became more complicated, especially after implementation of the Labour Relations Act of 1995. Employees received more information regarding their rights, which led to a situation where they insisted on reasons and feedback in cases where their applications were not successful. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2004. / Human Resource Management / unrestricted

African swine fever (ASF), a hemorrhagic disease of domestic pigs, is caused by a large enveloped icosahedral arbovirus of the Asfivirus genus in the family Asfarviridae . It has a linear, covalently close-ended, double stranded DNA (dsDNA) genome, 170 – 190 kbp in size. Warthogs (Phaecochoerus aethiopicus ), bushpigs (Potamochoerus porcus ) and soft ticks of the Ornithodoros genus are natural reservoirs of ASF virus (ASFV) in Africa. Serological differentiation between field strains is not possible and as no vaccine is available, control relies on stamping out and strict zoosanitary practices. In order to identify possible sources of virus and prevent further introductions, ASFVs need to be differentiated on genotype basis. Genotyping of East African ASFV isolates was achieved in this study by characterization of the C-terminal region of the major capsid protein gene, p72 . Thirteen genotypes were identified among East African sylvatic and domestic hosts. Of significance was the recovery of an apparently geographically restricted homogenous domestic pig cycle in the region, as well as the presence of viruses of the ESACWA genotype, formerly believed to be confined to Europe, South America, the Caribbean Islands and West Africa. Due to the conserved nature of the p72 gene, intra-genotypic relationships of viruses recovered from a homogeneous domestic pig-associated lineage, genotype VIII, could not be resolved. In an attempt to address this short-coming, genetic characterization of the Central Variable Region (CVR) within the 9-RL open reading frame (ORF) of the central conserved region of ASFV genome was conducted. Eight groups were resolved, some of which confirmed prolonged periods of circulation of a particular virus type, whilst others confirmed transboundary transmission of the disease. The complexity of ASF epidemiology in East Africa exemplified by the presence of a sylvatic and domestic pig cycle, multiple genotypes within countries and identical genotypes shared by multiple countries, was revealed. The East African ASFV molecular epidemiological database created in this study will be of great assistance to veterinary officials implementing prevention and outbreak control strategies. / Dissertation (MSc)--University of Pretoria, 2007. / Zoology and Entomology / unrestricted