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General Introduction
Tuberculosis (TB) is one of the leading human infectious diseases in the 21th century, with approximately 9 million cases reported and above 1.5 million deaths in the year 2013.2 Mycobacterium tuberculosis is primarily known as the causative agent of human TB. However, three other members of the Mycobacterium tuberculosis complex, namely Mycobacterium bovis, Mycobacterium africanum and Mycobacterium canettii can cause TB in humans.3 In cattle, Mycobacterium bovis is primarily known as the causative agent of bovine tuberculosis (BTB), however research has shown that other members of the Mycobacterium complex, particularly M. tuberculosis, can cause TB in livestock.4
In 1882, Koch and Behring were under the impression that M. tuberculosis was attenuated in bovines and could be used as a vaccine against M. bovis in cattle.5 Conversely, Mycobacterium bovis was thought to be less virulent in humans and could be used as a vaccine in man against M. tuberculosis. With further research, virulent human tubercle bacilli were isolated from milk of a vaccinated cow and more supporting literature stated that BTB has zoonotic (infectious disease that can be transmitted between animals and humans) potential and can be detrimental to human health.6,7 Mycobacterium tuberculosis has also been shown to be virulent in cattle. For instance, Berg et al., (2009), reported the isolation of M. tuberculosis from TB suspect lesions in cattle in Ethiopia, suggesting mycobacteria transmission from human to animals.4 Similarly M. tuberculosis was isolated from cattle showing typical tuberculous lesions at slaughter in South Africa (Michel, unpublished data). However, there is limited literature on the virulence of M. tuberculosis in bovines within southern Africa and little research has been done on the socio-economic impact M. tuberculosis has on livestock farming.8 In addition, there is an inadequate understanding of the Mycobacterium tuberculosis complex epidemiology at the interface between humans and animals (both wildlife and livestock). Investigating this interface is essential in the fight against the TB epidemic overall, as better understanding of the disease epidemiology will assist in designing suitable interventions to prevent disease spread and containing reservoir hosts.
Due to cultural traditions and poverty, many households in developing countries rely on obtaining dairy and other livestock products from subsistence cattle farming or communal small scale farmers. In some households these communal products are the main affordable source of animal protein, particularly for the very young and the old. Additionally, there is a common perception that raw milk and its products are more tasty and nutritious. However, the main limitation of livestock products derived from communal as compared to commercial farming, is the limited access to veterinary inspection before human consumption, raising questions with regard to food safety. A study in the Southern Highlands of Tanzania, isolated M. bovis from raw milk; thus, selling of unpasteurised dairy products such as raw milk, sour milk, and unpasteurized cheeses, which is very common in these areas could be of potential public health concern.9 Undetected pathogens including those causing zoonotic BTB may be prevalent within communities, with little or no adequate control measures. Under-resourced health centre services and infrastructure do contribute to low detection and under-diagnosis of zoonotic diseases. Collaboration of these health centres with research institutes would not only assist in the fight against zoonotic diseases but would aid in establishing if there is the presence of these diseases, their significance and population group at risk.
Chapter 1: Literature review
1.1 General Introduction
1.2 Mycobacteria
1.3 Clinical signs
1.4 Diagnosis of tuberculosis in cattle
1.5 Genotyping techniques .
1.6 Cost and socio-economic impact of bovine tuberculosis
1.7 Control of zoonotic TB
1.9 Aims and objectives .
1.10 References .
Chapter 2: Spillback transmission of Mycobacterium bovis from wildlife in the Greater Kruger National Park Complex to neighbouring livestock
2.1 Abstract
2.2 Introduction
2.3 Materials and Methods
2.4 Results
2.5 Discussion
2.6 Conclusion .
2.7 Acknowledgments
Chapter 3: Lack of evidence for tuberculosis transmission at the livestock/human interface in a rural Mnisi community, Mpumalanga province, South Africa.
3.1 Abstract .
3.2 Introduction
3.3 Materials and methods
3.4 Results .
3.5 Discussion
3.6 Conclusion
3.7 References
Chapter 4: Characteristics of tuberculosis patients and the evaluation of compliance to the national TB management guidelines at clinics in a rural community in Mpumalanga province, South Africa
4.1 Abstract
4.2 Introduction
4.3 Materials and methods
4.4 Results
4.5 Discussion
4.6 Conclusion .
4.7 Acknowledgements .
4.8 References
Chapter 5: Investigation into Mycobacterium tuberculosis and Mycobacterium bovis in patients at the wildlife/livestock/human interface, Mpumalanga Province, South Africa
Chapter 6: General discussion and conclusion
Appendices .
