The primary objective of this study was to determine the prevalence of subclinical gastroduodenal ulceration (GDU) in a population of Dachshunds undergoing decompressive surgery for acute intervertebral disc prolapse (IVDP). Secondary objectives included determining the extent to which treatment with ulcerogenic drugs, prior to admission, and the severity of spinal injury, would influence the prevalence of GDU. It aimed to further establish patient risk profile components (for example: age, weight, sex or concurrent disease conditions) that might influence the prevalence of GDU and make suggestions as to whether all dogs presenting with acute IVDP should be treated with anti-ulcerogenic drugs on admission for decompressive surgery. Thirty Dachshunds were admitted into the study after a diagnosis of acute IVDP was confirmed based on clinical signs and lumbar myelography. Full histories were obtained from both the owners and the referring veterinarians. Information obtained included any previous history of spinal disease, duration of clinical signs, rate of deterioration of clinical signs and drugs administered prior to admission. A full clinical and neurological examination was performed on each patient at admission. Blood and serum chemistry samples were taken to rule out any concurrent diseases that may have contributed to the development of GDU. Three regions in the stomach (cardia, corpus and pyloris) as well as the proximal duodenum were visualised using gastroduodenoscopy. The following criteria were assessed: colour and appearance of mucosa, presence and distribution of erosion, ulceration and/or submucosal haemorrhages. These results were combined with those obtained from histopathology of pinch biopsy samples, taken from the same four regions, in order to obtain the overall prevalence. Criteria used to assess histopathology of the regions included: disruption of the epithelial lining, haemorrhage into the submucosa and infiltration of neutrophils or macrophages into the submucosa. All dogs were scoped and biopsy samples taken on the first day of admission and three to four days post-surgery. Seventy six percent of Dachshunds that presented with IVDP had visual and/or histopathologic evidence of GDU. The highest overall prevalence of GDU was shown to occur in the pyloric region of the stomach both pre- and post-surgery. No significant correlation was found between the prevalence of GDU and the administration ulcerogenic drugs prior to admission. Similarly, no correlation was found between GDU and the severity of neurological signs, the duration of clinical signs prior to admission, the length of the procedure (general anaesthesia or surgery), age weight or sex. No significant statistical difference was found between the pre- and post-surgery results. Veterinarians should be aware of this potentially serious complication when dealing with Dachshunds with acute IVDP. The judicious use of ulcerogenic drugs and early use of prophylactic anti-ulcer medication is recommended in all patients presenting with this condition. / Dissertation (MMedVet (Surg))--University of Pretoria, 2003. / Companion Animal Clinical Studies / unrestricted

In order to investigate the increased serum urea: creatinine ratio encountered in canine babesiosis in South Africa, packed cell volume (PCV), serum haemoglobin, serum total bilirubin, plasma ammonia, serum urea, serum creatinine, calculated serum urea: creatinine ratio, serum cystatin-C, total serum protein (TSP) and urine analysis were performed in this study. The model consisted of 28 canine babesiosis patients, 25 in group 1, the anaemic group with PCV < 20%, and 3 in group 3, the haemoconcentrated group with PCV > 50%. 13 canine babesiosis negative dogs made up group 2, the control group. Unpublished human malaria data from 363 patients was also analysed and the urea: creatinine ratio was calculated in order to determine whether elevated serum urea: creatinine ratios also occur in this disease. The serum urea: creatinine ratio was > 20 in 23/25 anaemic patients, 3/13 control patients and 2/3 haemoconcentrated patients. The mean and median serum urea: creatinine ratio for the anaemic babesia group was 46.32 and 41.36, for the haemoconcentrated babesia group 25.10 and 20.85, for the malaria patients 20.64 and 18.75, and for the control group 15.91 and 15.36 respectively. Mean and median serum urea: creatinine ratio was significantly elevated and the distribution varied significantly between the anaemic babesiosis group compared with the control group (p=0.000003). Serum urea: creatinine ratio was elevated in canine babesiosis patients, especially when they are anaemic. The serum urea: creatinine ratio was also found to be elevated in the human malaria patients. Serum urea was found to be elevated in 17/25 anaemic patients, 0/13 control patients and 3/3 haemoconcentrated patients. Mean and median values for serum urea were 12.83 mmol/l and 11.8 mmol/l and 5.09 mmol/l and 4.3 mmol/l for the anaemic group and the control group respectively. Mean and median serum urea was significantly elevated and the distribution varied significantly between the anaemic group compared with the control group (p=0.00003). Serum creatinine was elevated in 0/25 anaemic patients 0/13 control patients and 2/3 haemoconcentrated patients. Mean and median values for serum creatinine were 72.08 <font face="symbol">m</font>mol/l and 67 <font face="symbol">m</font>mol/l, and 78.69 <font face="symbol">m</font>mol/l and 75 <font face="symbol">m</font>mol/l for the anaemic group and the control group respectively. Mean, median and distribution of serum creatinine did not vary significantly between the control group and the anaemic babesia group (p=0.274488). Serum cystatin-C was elevated in 0/25 anaemic patients, 0/13 control patients and 2/3 haemoconcentrated patients. The two haemoconcentrated patients with elevated serum urea and serum creatinine also had elevated serum cystatin-C. One of these two patients was available for post mortem and had significant renal lesions on histopathology. These two patients also had a urine specific gravity (SG) < 1.030 (1.020 for both cases). Mean and median values for serum cystatin-C were 0.71 mg/l and 0.7 mg/l, and 0.67 mg/l and 0.7 mg/l for the anaemic group and the control group respectively. Mean, median and distribution of serum cystatin-C did not vary significantly between the control group and the anaemic babesia group, (p=0.450172). Using the Spearman-rank test for correlation coefficients serum creatinine but not serum urea had a significant positive correlation with serum cystatin-C; and serum urea had a significant positive correlation with the serum urea: creatinine ratio. Log serum creatinine was significantly correlated to log serum cystatin-C, (r2=0.52, p<0.001). Log serum urea was also significantly correlated to log serum cystatin-C, (r2=0.14, p=0.024), however, this correlation was relatively poor compared to that of serum creatinine with serum cystatin-C. Log serum urea: creatinine ratio was not significantly correlated with log serum cystatin-C, (r2=0.014, p=0.485). Given its resistance to interference from the elevated plasma and serum pigments found in canine babesiosis, an elevated serum cystatin-C was taken to indicate significant renal disease. Therefore we can deduce that the increased serum urea: creatinine ratio encountered in canine babesiosis is a result of disproportionately elevated serum urea concentrations, which is of non-renal origin. A similar event appears to be present in human falciparum malaria patients. The cause of this phenomenon in either disease is unknown; but various forms of prerenal azotaemia, hyperureagenesis and laboratory perturbations may play a role. Serum creatinine was a better measure of significant renal disease than serum urea in this study. There also appeared to be no added benefit of measuring serum cystatin-C. Mean and median values for PCV were 11.64% and 11%, and 46.08% and 48% for the anaemic group and the control group respectively. As expected the mean and median PCV was significantly lower and the distribution varied significantly between the control group and the anaemic babesia group (p=0.000001). The mean and median values for PCV in the haemoconcentrated group were 54.33% and 54% respectively. Serum haemoglobin was > 1.6 g/l in 8/25 anaemic patients, 0/13 control patients and 3/3 haemoconcentrated patients. Mean and median values for serum haemoglobin were 1.72 g/l and 1.3 g/l, and 0.88 g/l and 0.8 g/l for the anaemic group and the control group respectively. Mean and median serum haemoglobin was significantly elevated and distribution of serum haemoglobin varied significantly between the control group and the anaemic babesia group (p=0.002364). Serum total bilirubin was > 15 <font face="symbol">m</font>mol/l in 11/25 anaemic patients, 0/3 haemoconcentrated patients and 0/13 control patients. Mean and median values for serum total bilirubin were 22.42 <font face="symbol">m</font>mol/l and 10.6 <font face="symbol">m</font>mol/l, and 10.63 <font face="symbol">m</font>mol/l and 11.0 <font face="symbol">m</font>mol/l for the anaemic group and the control group respectively. The median and the distribution of serum total bilirubin did not vary significantly between the control group and the anaemic babesia group (p=0.355888). TSP was elevated in 5/25 anaemic patients, was below the normal laboratory reference range in 5/25 anaemic patients, was elevated in 1/13 control patients, and was normal in all the haemoconcentrated cases. Mean and median values for TSP were 58.60 g/l and 54 g/l, and 60.92 g/l and 60.0 g/l for the anaemic group and the control group respectively. The mean, median and distribution of TSP did not vary significantly between the control group and the anaemic babesia group (p=0.130661).Plasma ammonia was elevated in 16/25 anaemic patients, 0/13 control patients and 2/3 haemoconcentrated patients. Mean and median values for plasma ammonia were 78.77 <font face="symbol">m</font>mol/l and 53.8 mol/l, and 23.18 <font face="symbol">m</font>mol/l and 21.5 <font face="symbol">m</font>mol/l for the anaemic group and the control group respectively. Mean and median plasma ammonia was significantly elevated and the distribution of plasma ammonia varied significantly between the control group and the anaemic babesia group (p=0.009562). Using the Spearman-rank test for correlation coefficients PCV had a significant negative correlation with plasma ammonia, serum urea and serum urea: creatinine ratio. Serum haemoglobin and serum bilirubin had a significant positive correlation with plasma ammonia, serum urea and serum urea: creatinine ratio. Plasma ammonia also had a significant positive correlation with serum urea and serum urea: creatinine ratio. These correlations may be explained by substrate loading as a result of haemolysis. I speculate that various protein by-products of haemolysis may cause the hyperammonaemia encountered via deamination of these proteins. This in turn may lead to ureagenesis, the physiological process of ammonia clearance. This ureagenesis may be excessive and therefore may account for the elevated serum urea encountered in patients with normal serum creatinine and serum cystatin-C concentrations. Alternatively the presence of an elevated serum haemoglobin concentration with its high intrinsic absorptive capacity in the 300 nm to 500 nm wave length range, may positively bias the measurement of serum urea and plasma ammonia concentrations. Serum urea is measured at 340 nm and plasma ammonia is measured at 365 nm. Thus a non-physiological process could also explain the above correlations. Urine analysis of the canine babesiosis patients showed mild evidence of renal disease as portrayed by proteinuria, renal tubular epithelium (RTE) celluria and granular casts. However, these findings, as well as the presence of an elevated serum urea, haemoglobinaemia and haemoglobinuria, bilirubinaemia and bilirubinuria, were present in both patients with mild renal disease and patients with overt renal disease. Therefore the benefit of single serum urea concentrations and random urine sediment analysis in canine babesiosis is questioned. Serial urine analysis monitoring was not investigated. This study concluded that serum urea is often elevated due to non-renal factors in canine babesiosis patients. This causes an elevated serum urea: creatinine ratio in this disease, with a similar event appearing to occur in human malaria patients. The cause of these elevated ratios remains undetermined, but is likely to be as a result of hyperureagenesis or laboratory error. The measurement of serum creatinine, urine SG and hourly urine production is advocated to detect significant renal disease in these patients. There appeared to be no added benefit derived from the measurement of serum cystatin-C concentrations in canine babesiosis patients in this preliminary study. / Dissertation (MMedVet (Medicine))--University of Pretoria, 2005. / Companion Animal Clinical Studies / unrestricted

Aviation is a global industry. Many professional pilots follow a career path that takes them into employment crossing national and international boundaries. They take with them their training, qualifications and experiences, and then build on these in diverse organisational and national cultural environments. They also carry with them their personal and professional attitudes, which then influence their behaviour. Professional pilots still often display a historically masculine attitude, which affects the relationship on the flight deck, particularly when one of the pilots is female. Because perceptions based on gender differences (real or alleged) have a pervasive and powerful influence on behaviour, it is important to manage gender diversity properly to meet the demands of a two-gender workplace. This has important implications for flight crew effectiveness and aviation safety. The study started with an overview of the literature, historical data on female aviators, selected relevant legislation and current world trends in aviation. A survey was then designed as the basis for a cross-cultural study of attitudes towards female pilots. The primary objective of this study was to develop a instrument to assess female and male aviators' perceptions regarding gender-related pilot behaviour across cultures and to determine the main and interaction effects of biographical variables on the perceptions held by professional pilots. The research group consisted of two non-probability samples: 183 pilots from the United States of America and 530 pilots from South Africa. An Aviation Gender Attitude Questionnaire (AGAQ) was devised to provide valid and reliable measurements of attitudes with regard to female pilots' Flying Proficiency and Safety Orientation. To determine the similarity or difference in the response patterns of the two samples, factor analysis, Tucker's coefficient of agreement and analysis of item bias were used. Univariate and multivariate analysis of variance were applied to uncover any possible main and interaction effects of the biographical characteristics on the respondents¡¯ perceptions of gender-related pilot behaviour. The results of the Principal Axis Factor Analysis performed on the AGAQ indicated little difference in the factor structures for the United States and South African groups. Tucker's phi-coefficient of congruence indicated factoral agreement (Tucker's phi ¡Ý 0.95) between the United States and South African respondents with regard to both factors of the AGAQ. The items of the two factors showed no uniform or non-uniform bias for pilots from the different culture groups. The results of the n-way ANOVAs and MANOVAs indicated that gender is the primary independent variable that has a significant effect (p< 0.001) on pilots' perceptions and attitudes towards female pilots. The mean scores for the female pilots were significantly higher than their male counterparts for both Flying Proficiency and Safety Orientation. The research findings are of particular interest in the field of Crew Resources Management (CRM) and ¡®Hazardous Attitudes¡¯ training. Topics such as gender issues and diversity management should be addressed to improve and advance gender-sensitive CRM training. Managing gender issues is critical to sustain and improve aviation safety and effective performance in mixed gender multi-crew environments. / Thesis (PhD (Human Resources Management))--University of Pretoria, 2004. / Human Resource Management / unrestricted

Employment equity initiatives often fail in organisations because of the negative perceptions and lack of support from members of the non-designated group towards the process of implementation of employment equity. The purpose of the study was to identify non-designated-friendly generic guidelines for the implementation of employment equity in an organisation. Phase one of the study comprised of qualitative research where a literature study was conducted on the methods used to introduce affirmative action, training of affirmative action candidates, and managing of diversity in the work place. During the second phase of the study a quantitative, survey-approach was followed to determine the perceptions and preferences of the non-designated sample (n-100) with regard to the implementation of employment equity. From the results of the survey a number of generic guidelines, which are acceptable for employees from the non-designated group, were identified. These guidelines can be utilised to minimise resistance when implementing employment equity measures in the workplace. / Dissertation (MCom (Human Resources Management))--University of Pretoria, 2004. / Human Resource Management / unrestricted

Reliability of quality of milk produced by smallholder farmers was assessed by means of a comparative analysis of the microbiological quality and somatic cell counts (SCC) of the raw milk obtained from dairy goats. Information regarding dairy goat farming and goat milk production in and around Pretoria was initially determined by means of a questionnaire. With this information, dairy goat herds were selected for the study, based on the fact that these farms produced milk for both domestic and commercial consumption. The study was conducted on three commercial dairy goat farms each under a different production system, the extensive, semi-intensive and intensive production systems. The method of milking varied with the type of production system; hand milking, bucket system and pipeline milking respectively. Udder health under the respective production systems was assessed by means of bacterial analysis of udder half milk samples. Bacteriology of bulk milk samples was also determined in order to assess the level of hygiene in the milking environment. In addition, water samples from the different farms were analysed for their microbial quality. Results of these parameters were compared between the different production systems using the analysis of variance. Capability of safe raw milk production by smallholder dairy goat farmers was then evaluated from the results obtained. Reliability of the SCC as a reflection of goat udder health was also evaluated. Further assessment was carried out to determine the relationship between udder conformation and presence of intra-mammary infection and SCC of the raw milk. Bacteria potentially capable of producing either food poisoning or enhanced spoilage of raw milk were cultured from the goat milk samples. These included pathogens such as Staphylococcus aureus, Bacillus cereus and Enterococcus faecalis, found associated with use of milking machines as was the case in the intensive and semi-intensive production systems compared to the extensive production system. The prevalence of intramammary infection was 33.3%. Coagulase negative staphylococci were the most common cause of intramammary infection with a prevalence of 86.6% of the infected udder halves. They includedStaphylococcus epidermidis, Staphylococcus simulans and Staphylococcus intermedius. The remaining 13.4% of the infection was due to Staphylococcus aureus. Somatic Cell Counts were not a reflection of udder health status, hence, not reliable in the prediction of goat udder health (p = 0.2 Fisher’s exact test of association). No significant relationship was proved to exist between the udder conformation and presence of intra-mammary infection or SCC of the milk produced. Raw milk obtained by the bucket system milking machine had the lowest total bacterial count (TBC) (16 450 Colony Forming Units per millilitre [CFU/ml]) as compared to that by pipeline milking machine (36 300 CFU/ml) or hand milking (48 000 CFU/ml). In comparison to the other two production systems, it was shown that dairy goat farming under the extensive production system, where hand milking was practised, was adequate for production of safe raw goat milk. Coliforms were found to be the most predominantly isolated organisms from the raw milk obtained under the extensive production system. However, these can be eliminated by pasteurisation of the milk. The extensive production system, therefore, could be a means to promote dairy farming in developing communities through smallholder farmers. This could be facilitated by extension services aimed at monitoring management on the farms. This would, consequently, help alleviate the problem of food security and low income in these communities. / Dissertation (MMedVet (Hyg))--University of Pretoria, 2003. / Paraclinical Sciences / unrestricted

The State Theatre Dance Centre forms part of the regeneration and upliftment of the Pretoria CDB. The STDC (State Theatre Dance Centre) is proposed to be sited directly opposite the South African State Theatre, in the CBD of Pretoria. The proposed site for the STDC, urban-infill project is an underutilized and undeveloped portion of land along Pretorius Street. Throughout the project the context was sensitively investigated and considered. The proposed building does not attempt to aesthetically ‘blend’ with the surrounding buildings but is rather the product of considering the opportunities and constraints that have been highlighted throughout the thesis whilst attempting to breathe new life and innovation into the environment. The thesis highlights the importance of the spaces found in-between elements within the built environment, as it are the se spaces that express and infuse individual elements with life and energy. Dance comes to life as a series of frames of movement. The choreographer positions dancers’ bodies within space to create a continuous flow of ‘frames’ where the relationships between dancers are expressed by the spaces in-between them. This idea is expressed throughout the thesis as the project develops through the different stages. / Dissertation (MArch (Prof))--University of Pretoria, 2006. / Architecture / unrestricted

In this study the sensitivity and specificity of an immunoperoxidase technique for the detection of lentiviral protein in formalin-fixed lung tissues of sheep were assessed. Formalin-fixed specimens of lungs of 52 sheep originating from two different infected flocks and formalin-fixed lung specimens of 20 sheep from a third, non-infected flock were selected. Multiple sections from each animal were stained with a monoclonal antibody against Maedi-Visna Virus (MVV) antigen. Control sections were stained with an irrelevant antibody, and without antibody, respectively in both the positive and negative groups. Histologic lesions of Maedi were graded according to severity and the number of sections staining positive. The average count of infected cells was determined for all animals which exhibited positive staining against viral protein. It was determined that the IMP technique had a sensitivity of 51,9% and a specificity of 100% if three sections of each animal were examined in both infected flocks. The sensitivity was greatly influenced by the presence or absence of typical histological lesions and the average cell counts seem to be correlated with the severity of the histological lesions. Animals without histological lesions were mostly negative with the IMP technique. The sensitivity was also influenced by the number of sections examined per animal and decreased if fewer sections were examined. Statistical analysis confirmed that the proportions of sections which were positive by means of IMP staining differed significantly between the four histological categories of normal, mild, moderate and severe. The more severe the lesions, the higher the proportion of sections were that could be diagnosed as infected by means of the IMP technique. It also confirmed that the ability to detect MVV infection in sections decreases significantly with a smaller sample size. In conclusion it would seem that this technique may be used in confirming infection in individual animals selected on the presence of typical pulmonary lesions. It is, however, not suitable as a routine screening test for the infection. / Die sensitiwiteit en spesifisiteit van die immunoperoksidase tegniek (IMP) vir die diagnose van lentivirus in formalien-gefikseerde longweefsel in skape was ondersoek. Formalien-gefikseerde long monsters van 52 skape , afkomstig van twee verskillende besmette kuddes, en formaliengefikseerde long monsters van 20 skape afkomstig van ‘n derde, nie-besmette kudde, was ondersoek. Veelvuldige histologiese snitte van elke dier was gekleur met ‘n monoklonale teenliggaam teen die Maedi-Visna Virus (MVV) antigeen. Kontrole snitte was gekleur met ‘n irrelevante teenliggaam, en sonder teenliggaam, in alle diere. Histologiese letsels was gegradeer ooreenkomstig die ergheidsgraad van die letsels; en die aantal snitte wat positief gekleur het per dier. Die gemiddelde aantal selle wat positief gekleur het vir antigeen was ook bepaal. Die IMP tegniek het ‘n sensitiwiteit van 51,9% en ‘n spesifisiteit van 100% indien drie long snitte per dier in beide die besmette kuddes ondersoek word. Die sensitiwiteit was grootliks beïnvloed deur die teenwoordigheid of afwesigheid van tipiese letsels en die aantal selle wat virus antigeen bevat blyk om te korreleer met die graad van die letsels. Diere sonder tipiese histologiese letsels was meestal negatief vir virus antigeen met die IMP tegniek. Die aantal snitte ondersoek het die sensitiwiteit beïnvloed en ‘n afname in die sensitiwiteit was opgemerk indien minder snitte per dier ondersoek was. Statistiese ontleding het getoon dat dat die aantal snitte wat positief toets met die IMP tegniek betekenisvol verskil tussen die histologiese kategorieë van erg, matig, lig en normaal. ‘n Groter persentasie van die snitte het positief gekleur in gevalle met meer gevorderde letsels. Dit het ook getoon dat die vermoë om MVV infeksie te diagnoseer betekenisvol afneem met vermindering in die aantal snitte wat ondersoek word. Die gevolgtrekking is dus dat die IMP tegniek van diagnostiese waarde is in individuele diere met tipiese histologiese letsels, en dat dit nie geskik is nie as ‘n roetine siftings-toets op kudde basis. / Dissertation (MMedVet (Pathology))--University of Pretoria, 2002. / Paraclinical Sciences / unrestricted

The reported incidence of human campylobacteriosis has markedly increased in developed countries within the last 20 years. The prevalence and importance of Campylobacter spp. as the cause of human gastroenteritis in developing countries is not known, as information is limited due to a lack of national surveillance programmes in these countries. However, it seems likely that the rate of campylobacteriosis is high among infants and children below 2 years of age resulting in substantial morbidity and, to a lesser extent, mortality. The aim of this study was to determine the extent of contamination and cross-contamination of poultry products with Campylobacter in a high-throughput South African chicken processing plant. It is the first research project for the evaluation of the zoonotic risk of Campylobacter for consumers in South Africa. While conventional culture-based detection methods of Campylobacter spp. usually need 4-6 days to produce a result, the polymerase chain reaction (PCR) method developed for this research project took less than 32 hours. Both strains, C. jejuni and C. coli, are the subject of this paper and will be collectively referred to as Campylobacter unless otherwise stated. During the winter of 2004, 300 samples were randomly taken from 50 chicken carcasses directly after evisceration, as well as 25 samples from ready-to-sell packages of fresh intestines (mala) and livers. The samples were taken in batches over a time period of 4 weeks. All samples were examined by means of DNA extraction and PCR resulting in the following findings: The average contamination rates with Campylobacter for both the skin samples and livers were 24%, and for intestines a contamination rate of 28% was found. These results are in line with the findings of other authors. Chicken and chicken products, especially livers and intestines form an important part of the traditional diet and reflect the special African situation. They are cheap and easily available outside supermarkets and other retail outlets. Street vendors and hawkers who do not have cooling facilities or access to and washing facilities sell the products. The break in the cold chain, especially under South African climatic conditions, favours the multiplication and consequently the increase of numbers of Campylobacter bacteria already present in the products. The handling of such contaminated products in households and the potential for cross-contamination of other foods presents a high risk of infection to consumers. This research project concludes that Campylobacter is prevalent in poultry in South Africa and that the contamination of poultry meat and products with this organism could represent a health hazard for consumers in South Africa. It also emphasises the need for further research in this field. Copyright 2005, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bartkowiak-Higgo, A 2005, A survey of post-evisceration contamination of broiler carcasses and ready-to-sell livers and intestines (mala) with Campylobacter jejuni and Campylobacter coli in a high throughput South African poultry abattoir, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-02272006-101843 / > / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2005. / Paraclinical Sciences / unrestricted

Tick resistance to acaricides is an increasing problem in South Africa and poses a real economic threat to the livestock and veterinary pharmaceutical industries. New acaricides are extremely expensive to develop so the present acaricides should be seen as an ever-diminishing resource, which should be protected by all means possible. The main objective of the study was to detect the levels of tick resistance to acaricides at selected commercial and communal farms in South Africa. Also to compare the in vitro adult and larval test methods and to investigate acaricide management strategies which may increase the lifespan of the presently used acaricides. To meet these objectives a field survey (February 2000 to August 2001) was carried out at selected communal and commercial farms in the Eastern Cape and Northwest Provinces of South Africa to monitor levels of field tick resistance to acaricides. The larvae were originally obtained from engorged female A. hebraeum, B. decoloratus, R. appendiculatus and R. evertsi evertsi. The larvae were tested against different concentrations of amitraz, chlorfenvinphos and cypermethrin using the Shaw Larval Immersion Test (SLIT). Mortality dose data were subjected to probit analysis using a BMDP statistical package. Factors of resistance (FOR) were calculated by comparing the larval response of ticks from the field, which had been exposed to acaricides, with baseline data from very susceptible laboratory strains of ticks, on the basis of the LC50 values. On the communal farms high levels of tick resistance were detected to cypermethrin as well as partial resistance to chlorfenvinphos whilst no resistance was detected against amitraz. On the commercial farms, however, ticks were equally resistant to amitraz, cypermethrin and chlorfenvinphos. The populations of B. decoloratus on these farms had developed higher levels of resistance to the test acaricides than the equivalent R. evertsi evertsi, R. appendiculatus and A. hebraeum populations. Higher levels of tick resistance to amitraz was observed on commercial farms than on communal farms, however, there was no significant differences in tick resistance to chlorfenvinphos and cypermethrin at both the commercial and communal farms. It was surmised that inappropriate use of acaricides might have resulted in higher tick resistance to the currently available acaricides on the commercial as well as the communal farms. Correct acaricide usage may solve this problem to a limited extent. Comparative in vitro tests were also carried out on the larvae and adults of B. decoloratus to determine the susceptibility of this tick to different concentrations of the currently used acaricides, (amitraz, chlorfenvinphos and cypermethrin) at three commercial dairy farms, (“Brycedale”, “Sunny Grove” and “Welgevind”) near East London in the Eastern Cape Province of South Africa. Resistance of field strains of B. decoloratus were determined using the SLIT and the Adult Immersion Test (AIT) as the latter test took into account factors such as oviposition assessment and reproductive ability. At “Brycedale”, resistance to amitraz and chlorfenvinphos was detected with the AIT method. Emerging resistance to amitraz and resistance to chlorfenvinphos were also detected at “Brycedale” with the SLIT method. At “Sunny Grove” resistance was detected to cypermethrin and at “Welgevind” resistance was detected to chlorfenvinphos with the SLIT whilst no resistance was detected using AIT. It would appear that the B. decoloratus populations tested on these dairy farms were more resistant to chlorfenvinphos than to amitraz or cypermethrin. Variable results were obtained using the SLIT, the Reproductive Estimate Test (RET) and the Egg laying Test (ELT). Nearly 50% of the dairy farms sampled showed resistance to chlorfenvinphos and the majority had susceptible B. decoloratus populations to both amitraz and cypermethrin. “Brycedale” had a serious resistance problem whilst “Sunny Grove” and “Welgevind” dairies had much less resistance problems. At “Brycedale”, the SLIT, RET and ELT methods all recorded resistance to amitraz and chlorfenvinphos whilst cypermethrin resistance was also detected with the ELT. At “Sunny Grove”, the SLIT detected emerging resistance to chlorfenvinphos and resistance to cypermethrin while the other two test methods were negative. At “Welgevind” the SLIT detected resistance to chlorfenvinphos and the ELT resistance to cypermethrin whilst the RET did not detect any resistance at “Welgevind”. In general there was a good correlation between the RET and the ELT whilst in many cases there was poor correlation between the SLIT and the two AIT methods (RET and ELT). From this study it would appear that the ELT was a good method to detect resistance within seven days, as opposed to the 42 days required for the RET and the 60 days for the SLIT. The ELT and the RET could possibly be used as screening methods to detect acaricide resistance on farms whilst the SLIT would remain the test of choice for National surveys. In addition the ELT is less costly and does not require sophisticated equipment for field testing for resistance, compared with other in vitro test methods. This method, however, still needs to be validated and standardized for use in South Africa and the rest of Africa where tick control is important. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2002. / Veterinary Tropical Diseases / unrestricted

The main objective of the study was to investigate whether there were significant differences in prevalence of antibodies to Babesia bigemina and Babesia bovis between vaccinated and unvaccinated cattle in a tick-borne disease endemic area of South Africa. The study was carried out between August 2000 and June 2001, in the Northern Province of South Africa at Nooitgedacht ranch (24° 33’ S and 28° 36’ E), where calves were vaccinated against B. bigemina and B. bovis infections, and at Vlakplaas ranch (24° 58’ S and 28° 05’ E), where calves had not been vaccinated against these parasites. Sera were collected from cattle of different age groups at both ranches and the presence of antibodies against B. bigemina and B. bovisdetermined using the indirect fluorescent antibody (IFA) test. It was found that B. bovis was absent from both ranches while B. bigemina antibody was more prevalent in cattle at Vlakplaas (unvaccinated) than at Nooitgedacht (vaccinated). The difference in B. bigemina antibody response between the ranches may have been due to variations in tick populations. Vlakplaas, which had been operated for 14 years with relaxed tick control, probably had sufficient numbers of vector ticks for frequent transmission and maintenance of endemic stability to B. bigemina. At Nooitgedacht, however, livestock farming had been interrupted for three years before it was resumed in 1999 and it is postulated that the tick population had been substantially reduced due to lack of hosts to a level insufficient for the establishment and maintenance of endemic stability to B. bigemina. The vaccinated cattle and breeding cows might therefore have lost IFA reacting antibody titres due to low levels of superinfections. The findings show that an endemically stable situation to B. bigemina could be achieved by adapting a tick control method that allows sufficient number of ticks on cattle rather than relying entirely on intensive tick control and vaccination. Therefore, it may not be necessary to vaccinate calves against B. bigemina on ranches located in B. bigemina-endemic areas and stocked with Bos indicus cattle or their crosses. Key words: Babesia bigemina, Babesia bovis, bovine babesiosis, tick-borne diseases, endemic stability, immunization, antibody response, Brahman, Bonsmara, South Africa. / Dissertation (MSc (Veterinary Sciences))--University of Pretoria, 2001. / Veterinary Tropical Diseases / unrestricted