ABSTRACT

Worldwide, tuberculosis (TB) kills about 2 million people per year. In South Asia, India carries the world’s largest burden of TB cases with approximately 2 million people developing the disease each year. In Nepal, about 45% of the total population is thought to be infected with TB and of that approximately 60% are of reproductive age. Though there is an association between indoor air pollution (IAP) and respiratory infections, the relationship between IAP and tuberculosis is not well understood. Previous studies have relied on cross-sectional designs or self-reported outcomes, making interpretation difficult. In order to further elucidate the effects of IAP on TB, the Fogarty International Research and Training Program in Indoor Air Pollution at the University of California, Berkeley (UCB) is collaborating with research centers in South Asia (3 in India and 1 in Nepal) to implement a multi-center study. Each site is conducting a hospital-based, case-control study to assess whether exposure to indoor air pollutants associated with combustion of biomass fuel increases the risk of developing pulmonary tuberculosis. Cases are restricted to women 15 years and older to minimize confounding due to tobacco smoke and because their exposure to indoor smoke is likely higher. Approximately 200 cases are being defined at each site based on diagnosis of active pulmonary tuberculosis at the hospital during a specified period of time. Controls are selected from females who present to the Medical, Surgical, or Gynecology departments of the participating hospital for medical conditions unrelated to indoor air pollution, are sputum negative, and have no recent history of tuberculosis. Exposure to IAP will be determined by an extensive questionnaire of past living arrangements including history of stove and fuel use and cooking experience. Indoor particulate air monitoring using the newly developed UCB PM Monitor will be conducted in case and control households at two sites. We will adjust for confounding between IAP and TB by socioeconomic factors, crowding, smoking, demographics, etc. The analysis will use logistic regression for each location separately as well as for the four sites together. Collaborative studies, such as these, designed and conducted with rigor, and repeated in a variety of locations will provide further understanding of the association between indoor air pollution and tuberculosis.