A Study of the Effects of Antiretroviral Therapy on Rates and Transmission of Tuberculosis

TB is the most common opportunistic infection and the single most common cause of death in HIV infected people in Africa today. Latent TB infection has been known to revert to active TB following new infection in HIV infected people; also, TB has been shown to accelerate the progression of HIV disease. These epidemiologic relationships between TB and HIV and the high prevalence of these diseases in sub-Saharan Africa make studying TB and HIV infected populations in this region of the world important. The Masiphumelele Township of Cape Town, South Africa, with its high rates of TB and HIV, is representative of many poor communities in Africa. The purpose of this study is to observe people from the Masiphumelele Township over a 5-year period to assess the prevalence of TB and HIV infections in a random sample of people and the clinical and genetic characteristics of active TB infection.

This study has two parts: a random cross-sectional survey and a clinical and genetic assessment of TB patients. Participants in the random survey will only be involved with the study for a maximum of 2 days. The purpose of the first part of the study is to compare the prevalence of active TB and the prevalence of HIV infection in a random sample of people from the Masiphumelele Township. In this part of the study, children and adults will be randomly selected from the township population to determine the prevalence of active TB and the prevalence of HIV infection in this group of people. Fieldworkers will identify eligible participants in the township and will ask them to visit the clinic that day or the next. At the clinic, participants will be asked to complete a demographics and TB history questionnaire and provide a saliva sample for anonymous HIV testing. A sputum sample will be collected from each participant with a nebulizer; each participant will also be given a sputum sample bottle and will be asked to collect an early morning sputum sample on the next day that will be returned to the clinic.

The second part of the study will enroll TB patients. Participants in this part of this study will be followed for the course of their TB treatment for at least 6 months. The purpose of the second part of the study is to assess changes through time of the clustering and transmission of TB among HIV infected and uninfected people in the Masiphumelele Township. This assessment will include examining the diversity of TB strains in this population and determining the relationship between recurrent cases of TB and HIV infection. All sputum samples indicating TB infections that were previously collected from participants will undergo genetic testing by restriction fragment length polymorphism (RFLP) analysis. Participants will be asked to complete a demographics and TB history questionnaire and provide a saliva sample for anonymous HIV testing. Participants will also be interviewed about treatment they have received for TB, their responses to this treatment, and whether they are currently on highly active antiretroviral therapy (HAART) for the treatment of HIV infection.

Participants who are found to be infected with TB during the first part of the study will be offered TB treatment through the clinic and will be invited to participate in the second part of this study. Participants who are found to be infected with HIV during the study will be referred to further treatment and evaluation.