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The reversal of low level gamma irradiation induced aberrations in the rat testes : a histological endocrinological and sperm kinematic evaluationMabeta, Peaceful Lucy 29 March 2005 (has links)
Radiotherapy for cancer produces prolonged testicular damage that is manifested by failure of spermatogenic recovery following treatment. It has thus become important to develop methods to induce the recovery of spermatogenesis, if fertility is to be restored in patients (De Vita et al., 1997). The importance of steroid hormones in the control of testicular function has lead to numerous studies being conducted on the use of these hormones as treatment to protect the testes from radiation damage (Desjardins and Ewing, 1993; Kurdoglu et al, 1994; Kangasniemi et al., 1996a; Shuttlesworth et al., 2000). x The aim of this study was to investigate the effects of low dose gamma irradiation on the rat testes and the use of testosterone to reverse damage to the testes resulting from radiation exposure. Sprague Dawley rats were subjected to irradiation doses of 3.5 and 6.0 Gy. The rats were treated with testosterone over 4 and 8 weeks. Analyses were carried out at three levels: histological, kinematic, and endocrine. Irradiation led to a dose dependent reduction in spermatogenic cell numbers. Percentage sperm motility was decreased, and two of the five measured kinematic parameters, curvilinear velocity and straight line velocity, were decreased. Luteinising hormone (LH) and follicle stimulating hormone (FSH) concentrations increased in a dose dependent manner, while testosterone concentration showed insignificant fluctuations. Following testosterone administration, spermatogenic cell numbers improved. LH concentrations were restored to almost control levels. Testosterone administered following exposure of the rat testes to low dose gamma irradiation led to the recovery of spermatogenesis. / Dissertation (MSc)--University of Pretoria, 2002. / Anatomy and Physiology / Unrestricted
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Cardiac histopathology and electrocardiographic changes in canine babesiosisDvir, Eran 29 March 2005 (has links)
Electrocardiographic (ECG) changes have never been reported in canine babesiosis. Based on the metabolic, electrolyte, and myocardial alterations described for the disease, such changes are to be expected. The purpose of this study was to describe ECG changes in canine babesiosis, and to correlate those changes to clinical severity, outcome and cardiac histopathological changes. Four groups of dogs with babesiosis were studied: mild to moderate anaemia (n=40), severe anaemia (n=35), concurrent immune-mediated haemolytic anaemia (n=18) and complicated (n=28). Lead II ECG was recorded at admission for 1 minute in all dogs, and repeated after 24 hours in admitted dogs (groups II – IV). Six lead ECG was recorded in 88 dogs. Full necropsy was performed between 30-60 minutes after death on 16 dogs (5 died on arrival, 11 had ECG recording). Gross cardiac pathology was recorded and histopathology of myocardial sections from ventricles, atria, apex and interventricular septa was evaluated, using a scoring system for haemorrhages, necrosis, inflammatory infiltrate and fibrin microthrombi. The following ECG changes were recorded: sinoatrial (7%) and atrioventricular blocks (4%), ventricular premature complexes (7%), low R-amplitude (23%), prominent Q (33%), axis deviations (40%), prolonged QRS (32%), ST depression and coving (28%), large T (42%), and notched R (28%). Differences between groups were minor and inconsistent. Gross pathological changes were pericardial effusion (25%) and subepicardial (56%) and subendocardial haemorrhages (63%). Histological changes were haemorrhages (69%), necrosis (50%), inflammation (63%) and fibrin microthrombi (75%). The only correlation between pathology and ECG was low R-amplitude and pericardial effusion. There was a significantly higher prevalence of sinus bradycardia and irregular sinus rhythm in the non-survivors. Both ECG and pathological changes were non-specific, but there were similarities to the pattern of changes that have been described for myocarditis and myocardial ischaemia. Antiarrhythmic treatment was only required in 1 dog. Thus, the clinical application of the ECG changes found in this study was limited. It was concluded that the heart suffers from the same pathological processes described in other organs in canine babesiosis, namely inflammation and hypoxia. Cardiovascular management, if necessary, should be based on functional monitoring rather than ECG. / Dissertation (MMedVet (Med))--University of Pretoria, 2001. / Companion Animal Clinical Studies / unrestricted
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Exploring branding as part of the corporate communication strategy of the Girl Guides Association Of South Africa (GGASA)Le Roux, Alta S 22 May 2007 (has links)
The NPO sector has become a dominant economic force all over the world. With a base of more than 100 000 NPOs in South Africa, this sector, also known as the third sector, has become a force with which all in South Africa need to reckon. The size of the sector alone is an indication of the critically important role it plays in the development sector in our country. I have been working in the non-profit sector for more than 25 years. With this experience as background, my opinion is that the effect of the exponential growth of the sector is that NPOs are now sharing the market with for-profit corporations and public agencies. In almost all markets, NPOs face increasing competition – competition that has intensified the pressure these organisations face to find effective management methods. For survival and self-sustainability, it is imperative for NPOs to adopt the managerial techniques and systems of the for-profit corporations. It is my view that the implementation and management of corporate branding can contribute positively to improve communications and relationships with the internal and external audiences of NPOs in the same way as for-profit organisations. To prove this viewpoint I decided to use a case study focus to allow me to analyse the content of the corporate communication strategy of the Girl Guides Association of South Africa (GGASA) as a non-profit organisation. Following this approach, I endeavoured to establish the role which branding is playing in the organisation and how it can market itself to its internal and external audiences by using the organisation’s corporate brand. Three data collection methods were used, namely, document analysis semi-structured interviews and focus groups. Based on the above, the main research question for this study has been formulated as: “How can the GGASA develop/manage its corporate brand to communicate its image effectively to internal and external audiences?” Four sub-questions were formulated, focussing specifically on: the aims of the communication of the corporate branding; identity and image programme of the GGASA; the principles on which the communication of the corporate branding, identity and image programme of GGASA are based; the characteristics of the communication of the corporate branding, identity and image programme of the GGASA and what the perceptions of the internal and external audience are of the communication of the corporate branding, identity and image programme of the GGASA. In an attempt to answer this research question I endeavoured to link three theories, namely corporate communication, social marketing and branding in order to describe their integration within the NPO sector. By following this approach, a case can be made out that social marketing and corporate communication in the NPO sector is just as important as the organisation’s core service delivery business. Secondly, if an NPO is not sure what its brand is all about, such an organisation would be unable to implement any effective social marketing and/or strategic corporate communication, bearing in mind that the brand is the core and essence of an NPO and the pivot of all these actions. I am of the opinion that should the key recommendations of this study be put in place by the management of the GGASA, it will improve the implementation of its corporate communication, more specifically the corporate identity, image and brand management processes. This will in turn lead to an improvement in the effectiveness of the organisation’s communication and the achievement of its developmental objectives, which will enable them to position themselves as one of the new superbrands in South Africa, with real power to act on behalf of a perceived common good. In my opinion, the inclusion of recommendations provided by the GGASA target audiences during the field research enriched my own conclusions and recommendations. The recommendations were further formulated in such a way, that they could form the basis of a workable implementation plan for the management of the GGASA. This factor further enhances the value of the study. / Dissertation (MA (Development Communication))--University of Pretoria, 2005. / Information Science / unrestricted
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The detection of lumpy skin disease virus in samples of experimentally infected cattle using different diagnostic techniquesTuppurainen, Eeva S.M. 08 March 2005 (has links)
Lumpy skin disease (LSD), affecting cattle in Africa, Madagascar and the Middle East, is caused by a capripox virus that belongs to the family Poxviridae. The disease is of economical importance in endemic areas and the Office International des Epizooties classifies it as a “List A”- disease. Effective control of LSD requires accurate and rapid laboratory techniques to confirm a tentative clinical diagnosis. Comparative studies on different diagnostic tests used at different stages of the disease have not been done. The aim of this study was to compare the different tests that are available and to provide data to assist in the selection of a rapid and sensitive laboratory test for the diagnosis of LSD. Six seronegative, prepubertal bulls were infected via the intravenous route and kept in an insect-free facility. The course of infection was monitored. During a three months’ period blood and semen samples were collected for virus isolation and polymerase chain reaction (PCR), and skin biopsies for the PCR, virus isolation, transmission electron microscopy (TEM), histopathological examination and immunoperoxidase staining of tissue sections. Antibody titres were assessed using the serum virus neutralization test (SNT) and indirect immunofluorescence test (IFAT). The incubation period in infected animals varied from 4 to 5 days. The length of viraemia did not correlate with the severity of clinical disease. By using virus isolation the duration of viraemia was determined to be from 1 to 12 days and by PCR from 4 to 11 days, which is longer than has previously been stated. Virus was isolated from semen until day 43 post-infection (p.i.) whereas the PCR could detect LSD virus nucleic acid until day 161 p.i. Virus was isolated from skin biopsies until day 39 p.i. and PCR could demonstrate viral DNA in them until day 92 p.i. The PCR was a fast and sensitive method to demonstrate viral DNA in blood, skin and semen samples. It could detect viral nucleic acid for significantly longer periods than any of the conventional methods. Virus isolation from blood, skin and semen samples was sensitive and reliable, but as a single test it may be too time-consuming although this depends how rapidly the diagnosis must be confirmed. The IFAT can be used for rapid confirmation of a clinical diagnosis but it needs careful standardization due to non-specific staining. The SNT showed positive results later in the course of the clinical disease than IFAT but it was however, sensitive and reliable in detecting antibodies from all the animals in this experiment. Transmission electron microscopy of skin biopsies detected LSD virus only in one of the four bulls that developed skin lesions. This indicated that even though TEM is usually considered to be a fast and reliable method, a negative result must still be confirmed using another method. Histopathological changes of the skin lesions in sections stained with haematoxylin and eosin were typical for the disease. It was not possible to make a reliable diagnosis of LSD based only on immunoperoxidase staining of tissue sections. In conclusion, this study indicated the PCR to be superior in detecting LSD virus from blood, skin and semen samples. However, virus isolation is still required when the infectivity of the LSD virus is to be investigated. Even though the IFAT has been used for several decades, it is still a valuable tool in detecting antibodies against LSD virus. Both the SNT and IFAT are useful and reliable in retrospective, epidemiological studies. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2004. / Veterinary Tropical Diseases / unrestricted
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Development and validation of enzyme linked immunosorbent assays for detection of equine encephalosis virus antibody and antigenCrafford, Jan Ernst 19 April 2005 (has links)
The main purpose of this work was to develop rapid and reliable techniques that will prove valuable in epidemiological studies of equine encephalosis virus (EEV), the detection and identification of the virus for the laboratory confirmation of the clinical diagnosis and for the differential diagnosis between EEV and African horsesickness virus (AHSV). Two enzyme linked immunosorbent assays (ELISA) were developed. A polyclonal antibody-based, group-specific, indirect sandwich ELISA for the detection of EEV antigen was developed. The design of the assay was based on the methods currently used for the detection of AHSV. The cut-off value (absorbance of 0.15) was determined using populations of known negative specimens. No cross-reactions were recorded with viruses from other orbivirus serogroups or from other arboviruses. The assay proved to be sensitive and specific for the rapid detection of EEV and viral antigens in cell culture and mouse brain preparations. A polyclonal antibody-based, group-specific, competitive ELISA for the detection of antibodies to EEV was developed. No cross-reactions were recorded with the reference sera prepared against other orbivirus serogroups or other arboviruses. The cut-off (29.5% inhibition) value was determined using populations of known positive and negative sera. Analysis of the data showed the assay to be highly repeatable, sensitive and specific. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2001. / Veterinary Tropical Diseases / unrestricted
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The evaluation of a BCG vaccine against bovine tuberculosis in African buffaloes (Syncerus caffer)De Klerk-Lorist, Lin-Mari 08 March 2005 (has links)
To assist in the evaluation of BCG vaccination in African buffaloes (Syncerus caffer), an infection model for Mycobacterium bovis was established, using an intratonsilar route of inoculation. Two groups of 11 buffaloes each, aged approximately 18 months, were infected with either 3,2 x 102 cfu (low dose) or 3 x 104 (high dose) of virulent buffalo strain M. bovis. A control group of six buffaloes received saline via the same route. The infection status was monitored using the intradermal tuberculin test, an ELISA and a modified interferon-gamma assay. All buffaloes were euthanased 22 weeks post infection and the development of lesions in the left retropharyngeal lymph node was evaluated by macroscopic examination, mycobacterial culture and histopathology. It was found that the high dose caused macroscopic lesions in 9 out of 11 buffaloes that were comparable to that observed in buffaloes with natural disease. Mycobacterium bovis was isolated from all animals in the high dose and from 6 out of 11 buffaloes in the low dose group. The efficacy of a live BCG-Pasteur vaccine was tested in a group of buffalo calves captured in the northern districts of the Kruger National Park from herds with known negative tuberculosis status. Primary and booster vaccinations with BCG (1173P2) were administered to 15 calves, while another 15 were left unvaccinated as control animals. All the buffalo calves were challenged with the high dose of live M. bovis (as determined in the Infection Model) via intratonsilar inoculation. Laboratory tests were able to distinguish between infected and non-infected animals from an early stage. All buffaloes were euthanased 34 weeks after infection and the development of lesions in the lymph nodes of the head, thorax, carcass and abdomen was evaluated by macroscopic examination, mycobacterial culture and histopathology. The lungs were carefully palpated to detect the presence of tuberculous granulomas. Macroscopic lesions in the lymph nodes were found in 10 out of 14 control buffaloes and 7 out of 15 vaccinated animals. The lesions were comparable to that observed in buffaloes with natural infection. The lesion scores of individual animals were generally much higher in the BCG vaccine study than what was experienced with the Infection Model. Mycobacterium bovis was isolated from 12 out of 14 control animals and from 12 out of 15 vaccinated buffaloes. Although fewer vaccinated animals developed tuberculous lesions, the differences between the two groups were not statistically significant and it can be concluded that under the prevailing conditions the BCG vaccine was unable to protect buffalo calves against the establishment of M. bovis infection. / Dissertation (MSc (Tropical Diseases))--University of Pretoria, 2004. / Veterinary Tropical Diseases / unrestricted
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The development of an interferon-gamma (IFNγ) assay for the diagnosis of tuberculosis in African elephants (Loxodonta africana) and black rhinoceros (Diceros bicornis)Morar, Darshana 09 March 2005 (has links)
The objective of this project was to design tools for a diagnostic test that will prove valuable in the detection of tuberculosis in elephants and rhinoceros by using the cytokine IFNγ as an indicator of Mycobacterium bovis responsiveness. Interferon-gamma (IFNγ), a type II interferon, is a cytokine mainly produced by Th1 and cytotoxic T-cells expressing surface markers CD4 and CD8, respectively and natural killer cells (Ibelgaufts; 1999). In response to a mycobacterial infection antigen specific Th1- and cytotoxic T-cells are induced. When these cells encounter their specific mycobacterial antigen, they will respond by producing IFNγ. Based on this principle a diagnostic test was developed. In this test PBMCs will be stimulated with M.bovis specific antigen and the subsequent production of IFNγ by specific T-helper cells will be determined by IFNγ of elephants and rhinoceros. In order to develop such an assay recombinant elephant and rhinoceros IFNγ was cloned, sequenced, expressed, purified and subsequently a monoclonal antibody against IFNγ was produced. Monoclonal antibodies were selected by a number of ELISAs using recombinant IFNγ. Preliminary results are promising and further tests are underway regarding the specificity and sensitivity of the assay before field trials can be performed. The results of this study has significant implications in the design of an IFNγ diagnostic kit for the diagnosis of tuberculosis, as caused by M.bovis, in elephants and rhinoceros as well as other wildlife affected by this debilitating disease. / Dissertation (MSc (Veterinary Science))--University of Pretoria, 2003. / Veterinary Tropical Diseases / unrestricted
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Distribution of boophilus microplus and boophilus decoloratus and associated occurrence of babesia species in cattle in the Soutpansberg region, Northern Province, South AfricaTonnesen, Mirjam Hauke 23 March 2005 (has links)
Bovine babesiosis occurs worldwide and is one of the most costly tick-borne cattle diseases in the tropics. The Soutpansberg region of the Northern Province in South Africa is endemic for Babesia bigemina, but Babesia bovis was only reported from this area in the 1980s when some farmers experienced heavy losses due to Asiatic redwater. The main objectives of the study were to confirm the presence of the tick vector Boophilus microplus in the Soutpansberg region where it had not been reported previously, and to determine the seroprevalence of Babesia bovis and Babesia bigemina in cattle in these areas. Other objectives were to assess the relative numbers of Boophilus microplus in relation to Boophilus decoloratus and to determine a possible displacement of Boophilus decoloratus by Boophilus microplus. It was also the intention to map the potential distribution of the Boophilus ticks in the area and to more accurately predict the further spread of Boophilus microplus. Tick collections and serological surveys were carried out during 1999 and 2000 on cattle at 30 communal dip tanks and on 5 commercial farms in the Soutpansberg, Dzanani, Mutale, Thohoyandou and Vuwani Districts. Of the 25,042 Boophilus ticks collected, 93.9 % were Boophilus microplus and 6.1 % were Boophilus decoloratus. At 8 of the dip tanks/farms both Boophilusspecies were found, and the displacement of Boophilus decoloratus by Boophilus microplus was monitored at 4 of these sites. There was a distinct displacement of Boophilus decoloratus at those dip tanks/farms where repeated tick collection was possible. Cattle at the communal dip tanks carried larger Boophilustick numbers than cattle on the commercial farms. Boophilus microplus was the most common Boophilustick collected at the dip tanks, and during the survey it also became the Boophilustick most commonly found on the commercial farms. CLIMEX was used to map the potential distribution of Boophilus microplus and Boophilus decoloratus in the survey area during years with average as well as double average rainfall. Ecoclimatic Indices were computed for each sampling location, using 30 years of climatic information. The displacement patterns of Boophilus species were also discussed. Blood samples (n = 2201) were collected for Indirect Fluorescent Antibody (IFA) testing. Serological evidence of Babesia bovis was detected in 97 % of the communal dip tank herds and in 100 % of the commercial farm herds. The overall seroprevalence of Babesia bovis in the dip tank herds during 1999 and 2000 was 63 %. The seroprevalence of Babesia bovis in the commercial herds increased significantly from 19 % in 1999 to 57.5 % in 2000. There was a slight increase in endemic stability in comparable herds from 1999 to 2000. The increase in seroprevalence and endemic stability probably came as a result of the influx of Boophilus microplus into the survey area. There was a significant correlation between the presence of Boophilus microplus in the survey area and the increasing seroprevalence of Babesia bovis, which confirms that Boophilus microplus is the main and probably the only vector of Babesia bovis in South Africa. Serological evidence of Babesia bigemina was detected in 100 % of communal dip tank and commercial farm herds. The overall seroprevalence of Babesia bigemina in the dip tank herds decreased significantly from 56.1 % in 1999 to 49.3 % in 2000. There was a marked decrease in endemic stability for Babesia bigemina in comparable dip tank herds from 1999 to 2000. The decrease in seroprevalence and endemic stability to Babesia bigemina in these herds was probably due to the substantial increase of Boophilus microplus in the survey area. This may indicate that Babesia bigeminaa was transmitted less effectively by Boophilus microplus than by Boophilus decoloratus. The seroprevalence of Babesia bovis was significantly higher than that of Babesia bigemina at those dip tanks/farms where only Boophilus microplus was present during 1999 and 2000. This may be explained by the possibility that Boophilus microplus transmits Babesia bigemina less effectively than it transmits Babesia bovis. This survey raises several questions on the ability of the African strain of Boophilus microplus to transmit African Babesiastrains. There are indications that the African Boophilus microplus is different to the Australian Boophilus microplus. More research needs to be done to investigate how the Babesia species are transmitted in Africa. / Dissertation (MSc (Veterinary Sciences))--University of Pretoria, 2002. / Veterinary Tropical Diseases / unrestricted
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Identification and characterization of the primary infectious agents associated with ovine ulcerative balanoposthitis and vulvovaginitis in South AfricaKidanemariam, Awoke 09 March 2005 (has links)
Ulcerative balanoposthitis and vulvovaginitis is a disease characterized by erosion and ulceration of the glans penis and muco-cutaneous junction of the vulval lips of sheep. The disease was first recognized in South Africa in 1979 in the Calvinia district, Northern Cape province, and its distribution has since extended to all major Dorper sheep farming areas of the country with serious economic consequences. It is now a major concern for Dorper sheep breeders and farmers due to the fact that the disease has a detrimental effect on conception and subsequent lambing percentages. The aetiology and epidemiology of the disease are not well established. During this study the microbial flora in the genital tract of both clinically healthy and infected sheep were compared. The aim was to isolate and identify the pathogenic microorganism/s that contribute to the disease in sheep and to determine the in vitro antimicrobial susceptibility of the isolates. Flocks of sheep in the Northern Cape province showing clinical signs of ulcerative balanoposthitis and vulvovaginitis were examined. The microbiological flora of 116 clinically unaffected sheep and 104 affected sheep from 15 different farms, and with characteristic ulcerative lesions were examined. Swabs from rams and ewes were collected aseptically, and put into cryovials consisting of transport medium for bacterial, mycoplasmal and viral maintenance. Swabs for Chlamydophila species antigen detection were placed into tubes without transport medium. All specimens were processed for virus isolation in cell culture, Chlamydophila antigen detection with ELISA, and bacteria and mycoplasmas were isolated on standard culture media. The latter were further identified with biochemical tests and indirect immunofluorescence antibody (IFA) test. The IFA test was found to be useful when contamination with other microorganisms was prevalent, especially in genital tract specimens. This procedure had reduced the necessity for sub-culturing and cloning. The IFAT was found to be effective for the identification of Mycoplasma spp. growing on primary growth media in mixed cultures. The technique also helped to confirm the presence of mycoplasmas that did not produce typical colonies, and it was possible to identify mycoplasma colonies overgrown by bacterial contaminants. Bacteriological examination of materials from affected and unaffected ewes and rams resulted in the isolation of a sizeable number of Arcanobacterium pyogenes. It was isolated from 44.2 % affected sheep and 17.2 % healthy ones. This isolation difference was statistically significant (p<0.01). Seventy four per cent of the isolates came from severe clinical cases. There were no significant differences in isolations of Corynebacterium species and streptococcus species between normal and clinically affected sheep. The mollicutes isolated from the genito-urinary tract of the sampled sheep included Mycoplasma mycoides mycoides large colony, Mycoplasma species Group 7, Mycoplasma capricolum, Mycoplasma capri, Mycoplasma bovigenitalium, Mycoplasma agalactiae, Mycoplasma arginini, and unidentified Mycoplasma spp. and Acholepalsma laidlawii and Ureaplasma species. Mycoplasma was isolated from 49.3 % of 116 clinically normal sheep and 78.2 % of 104 affected sheep. There were significant differences in rates of isolation among clinical groups (p<0.05). Of all the mycoplasma isolates, Mycoplasma mycoides mycoides LC was isolated from 61.5 % of clinically diseased sheep while 6.0 % of the isolates were from apparently healthy animals (p<0.05). There was a significant association between the degree of the severity of the lesion and the rate of isolation of M mm LC (p<0.05). The extent of the isolation of M mm LC suggests a causal relationship with ulcerative balanitis and vulvitis in sheep in South Africa. The present findings, together with those of Trichard et al, (1993), showed that M mm LC is the major pathogenic mycoplasma incriminated in ulcerative balanitis and vulvitis in sheep in South Africa. However, results also point towards other pathogens such as A. pyogenes playing a role in the pathogenesis of the disease and predisposing the genital tract to infection with mycoplasma. A number of other identified and unidentified strains of mycolasma were isolated from both clinically affected and healthy sheep. However, in genital tract infection is uncertain. Virus isolation efforts in cell culture and Chlamydophila antigen capture ELISA yielded negative results in affected rams and ewes, and healthy sheep. Current clinical observations during this project have shown that the typical ulceration appears to be confined to the glans penis and lips of the vulva and no ulceration has been observed on the shaft of the penis and vaginal vestibule. In uncomplicated cases inflammation of the prepuce and vaginal vestibule is not a regular feature of the disease. Therefore, the name ulcerative balanitis and vulvitis most accurately describe the clinical signs of the disease in South Africa. Age-related susceptibility to the disease was observed. Young sheep are 2.5 times more likely to have the lesion than adult sheep (p<0.05). It was also observed that male sheep acquire severe lesions more often than female sheep. Since, infection in both male and female sheep can spread by coitus, it may valuable to attempt detection of infected animals and follow a strict isolation policy. In addition, further studies to elucidate predisposing factors related to management and environment are required. The in vitro activities of enrofloxacin, florfenicol, oxytetracycline and spiramycin were determined against field isolates of MmmLC by means of the broth microdilution technique. The minimum inhibitory concentrations (MIC) of these antimicrobial drugs were determined for a representative number of 10 isolates and one type strain. The susceptibility of A. pyogenes to enrofloxacin, oxytetracycline and tilmicosin was determined by means of agar disk diffusion test. The MICs of enrofloxacin, florfenicol, oxytetracycline and spiramycin were within the ranges of 0.125-0.5, 1.0-2.0, 2.0-4.0 and 4.0-8.0 µg mℓ-1, respectively. This study has shown that resistance of MmmLC against enrofloxacin, florfenicol, oxytetracycline and spiramycin was negligible. All tested field strains of A. pyogenes were susceptible to enrofloxacin, oxytetracycline and tilmicosin with mean inhibition zones of 30.6, 42.3&35.8 mm, respectively. Although, there is a lack of data on in vivo efficacy and in vitro MIC breakpoints of these antimicrobial drugs for MmmLC, the MIC results indicate that these 4 classes of antimicrobial drugs should be effective in the treatment of ulcerative balanitis and vulvitis in sheep in South Africa. / Dissertation (MSc (Microbiology))--University of Pretoria, 2003. / Veterinary Tropical Diseases / unrestricted
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The impact of two dipping systems on endemic stability of bovine babesiosis and anaplasmosis in cattle at four communal grazing areas in Limpopo Province, South AfricaRikhotso, Boetie Oupa 24 June 2005 (has links)
A twelve-month study was conducted at four communal grazing areas namely, Oakley, Cunningmore, Mkhuhlu and Ronaldsy in the Bushbuckridge region, Limpopo Province, South Africa. The main objective of the study was to investigate the impact of reduced acaricide application on the endemic stability to bovine babesiosis (Babesia bigemina and Babesia bovis) and anaplasmosis in a sample of the local cattle population. The study should be of assistance to farmers who are attempting to move from intensive to strategic tick control strategies and reduce the frequency of dipping, whilst maintaining endemic stability. Sixty cattle per communal grazing area were bled at the beginning and the end of the experimental period and the sera were assayed for B. bovis, B. bigemina and Anaplasma antibodies. Cattle in the intensively dipped group were dipped 26 times and maintained on a fourteen-day dipping interval throughout the study, whereas, cattle in the strategic group had their acaricide application frequency reduced and were only dipped 13 times. Three cattle per village were selected from which adult ticks were collected and immature ticks were also collected by dragging the veld. A questionnaire to assess the prevalence of clinical cases of tick-borne diseases, abscessation and mortalities was completed by an Animal Health Technician at each diptank during dipping. This was done to determine the number of clinical cases of bovine babesiosis, anaplasmosis as well as abscessation. An increase in seroprevalence to B. bovis and B. bigemina and a decrease in seroprevalence to Anaplasma was detected in the strategically dipped group whilst in the intensively dipped group a decrease in seroprevalence to B. bovis and B. bigemina and an increase in seroprevalence to Anaplasma was detected. Amblyomma hebraeum was the most abundant tick species found on the cattle in this region, whilst Rhipicephalus (Boophilus) microplus and Rhipicephalus (Boophilus) decoloratus were also collected and R. (B.) microplus was the more abundant of the two species. Drag samples yielded more A. hebraeum immatures than Rhipicephalus (Boophilus) and a seasonal pattern was displayed. An increase in the number of clinical cases of tick-borne diseases and abscesses was recorded at the beginning of the survey in the strategically dipped group. / Dissertation (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2005. / Veterinary Tropical Diseases / unrestricted
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