Babesia canis : a characterization of five field stocks in Southern Africa
- Authors: Van Heerden, Garth William
- Date: 1994
- Subjects: Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5645 , http://hdl.handle.net/10962/d1005327 , Babesia canis -- Africa, Southern , Tick-borne diseases -- Africa, Southern , Dogs -- Parasites
- Description: This study attempted to characterise 5 field stocks of B. canis, collected from various geographic areas of southern Africa in terms of pathogenicity, immune response, cross resistance and antigenic composition. This was done by means of artificial infection of two to four year old Beagle dogs. Serological tests included indirect fluorescent antibody tests, polyacrylamide gel electrophoresis , Western blotting of B. canis antigen and immune serum transfers. The ZIM1, GHT1 , QTN1 and DBN1 stocks were found to be virulent and the JHB1 stock, which might be a cardiac form of babesiosis, was found to be highly virulent. Immune responses of dogs to primary challenges were poor. A second challenge or relapse was important in the development of a resistant immunity. Heterologous challenges showed that dogs which were immune to the ZIM1, QTN1 and DBN1 stocks were partially immune to the JHB1 stock. The dog that was immune to the GHT1 stock was the only one that was totally resistant to the JHB1 stock. Western blots revealed interstock antigenic variation between the JHB1 and the other four stocks. These differences were, however, not great enough to separate the stocks taxonomically.
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- Date Issued: 1994
An investigation into the potential immunogenicity of various extracts of the South African bont tick Amblyomma hebraeum
- Authors: Adamson, Deborah Jane
- Date: 1993
- Subjects: Amblyomma -- South Africa , Ticks -- South Africa , Ticks -- Control -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4127 , http://hdl.handle.net/10962/d1015640
- Description: Rabbits and goats were inoculated with crude, membrane-associated and soluble components extracted from unengorged adult females and nymphs of the bont tick Amblyomma hebraeum. Inoculation provided some protection against nymphal infestation, however it had little effect on adult feeding. Histological examination of adults fed on inoculated hosts showed evidence of gut damage. Skin provocation testing with tick extracts elicited a Type I immediate hypersensitivity which was influenced by antihistamine. A delayed skin reaction was also evident. Whether this was attributable to Type III Arthus reaction or Type IV cell-mediated hypersensitivity was not determined. A comparative histological study of sites of tick extract injection, on inoculated and naive hosts, demonstrated the role of eosinophils in the hosts response to tick feeding. Serological examination revealed elevated anti-A hebraeum lgG titres following inoculation. These titres were found to decrease in the ten weeks after inoculation, despite the hosts being repeatedly infested with A hebraeum. Although the IgG titres of naive control hosts increased after each tick infestation, they failed to reach the titres achieved through inoculation. Western blot analysis of serum from inoculated hosts recognized most of the A. hebraeum proteins against which it was screened.
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- Date Issued: 1993
An investigation of Borrelia burgdorferi in South Africa
- Authors: Nurton, Jane Patricia
- Date: 1993
- Subjects: Ticks , Ticks as carriers of disease , Borrelia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5722 , http://hdl.handle.net/10962/d1005408 , Ticks , Ticks as carriers of disease , Borrelia
- Description: Four commonly occurring genera of ticks in South Africa were tested for their capacity to acquire and transmit Borrelia burgdoiferi, the causative agent of Lyme disease. Attempts were made to infect rabbits with a culture of B. burgdoiferi, and tick transmission experiments were carried out using the rabbits as the host of infection. Only one rabbit was successfully infected. Histological changes associated with a B. burgdoiferi infection were noted in this rabbit, but no spirochaetes were isolated. All other host animals failed to become infected with the B. burgdoiferi. As a consequence transmission experiments with the local ticks failed. Serological surveys conducted on rodents, horses and cattle using immunofluorescent and haemagglutination tests indicated that there is evidence that Borrelia species occur widely and that there is a possibility of B. burgdoiferi occurring in South Africa. Studies conducted on ticks from suspected endemic areas revealed the presence, in Ixodes bakeri only, of a spirochaete-like organism that reacted with monoclonal antibody H5332. Shortcomings of the study are highlighted and proposals are presented to address the problem of identifying specific B. burgdoiferi infections.
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- Date Issued: 1993