Mwaba, Peter; (2002) Application and use of technology for studies on tuberculosis and HIV in Africa. Doctoral thesis (Ph.D.), University College London.

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Abstract

In 1993, the World Health Organisation declared tuberculosis and HIV/AIDS global emergencies. One third of the world's population are infected with the tubercle bacillus, Mycobacterium tuberculosis, and each year, approximately 8 million infected people develop active tuberculosis. Three million people die of tuberculosis each year. The Human Immunodeficiency virus type 1, with an estimated worldwide prevalence of 32 million infected individuals has emerged as one of the major risk factors for the development of active tuberculosis. The burden of the two diseases, has had devastating consequences on the health and economies of the affected developing countries, particularly in sub-Saharan Africa. Large scale epidemiological and population based scientific studies on the two diseases have been hampered by lack of technical and laboratory support required to execute the research work in the field. Currently available tests for clinical and research use are expensive and require close proximity of well equipped research laboratories. Newer tuberculosis and HIV vaccines will require large scale population based studies utilising numerous biological samples for laboratory analyses and it becomes imperative that field friendly, cheaper technologies are developed and made available for use in the field. This project developed and evaluated the use of field-friendly technology for a variety of clinical and investigative situations in HIV/AIDS and tuberculosis research. This project demonstrated that: 1. CD4 measurements on dried blood spots on filter paper correlate closely with standard whole blood flow cytometry. 2. CD4/CD8 measurements can be performed utilising blood specimens collected in the field and stored in special fixative for delayed processing at a central laboratory in batches. 3a. HIV-1 viral load can be quantified accurately from plasma samples dotted and dried on filter paper. These measurements correlate very closely with standard HIV-1 viral load assays on corresponding liquid plasma (correlation coefficient =0.92). 3b. HIV-1 viral load can be quantified accurately from whole blood spotted and dried on filter paper. These measurements correlate very closely with standard HIV-1 viral load assays on corresponding plasma spots (correlation coefficient =0.89). 4. It was possible to utilise and apply the modifications of filter paper technology described above for HIV-1 viral load measurements in an ongoing clinical trial of tuberculosis in Lusaka. 5. Mycobacterial DNA can be recovered from; a) Mycobacterial cultures spotted and dried on filter paper. b) Sputum samples from infected patients dotted and dried on filter papers. The low pick up rate of mycobacteria from filter paper samples compared to conventional whole sputum indicate that further refinement of this method is required before it can be applied for field studies. Given the financial constraints and practical difficulties of laboratory measurements required for studies on tuberculosis and HIV/AIDS in Africa, the technologies evaluated in this study, suggest that their refinement and application may be a way forward. These technologies have potential application for use in the large-scale studies that will be required when HIV and Tuberculosis vaccines are tried out in the field.

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