Environmental and host-related determinants of tuberculosis in Metema district, north-west Ethiopia

Background: Each year, one third of the world's population is estimated to be infected with tuberculosis (TB). Globally in 2011, there were an estimated 8.7 million TB cases that resulted in 1.4 million deaths. In Ethiopia, TB is the leading cause of morbidity and the third most common cause of hospital admission. The aim of this study is to assess environmental and host-related determinants of TB in Metema district, north-west Ethiopia. Methods: A community-based unmatched case-control study was conducted from March 12 to April 5, 2013. The study population included 655 subjects (218 cases and 437 controls in a ratio of 1: 2). Cases were TB patients selected from a total of 475 cases registered and treated from March 2012 to February 2013 at the Metema District Hospital DOTS (direct observation therapy, short-course) clinic and selected randomly using a lottery method. Controls were people who had had no productive cough for at least 2 weeks previously and were selected from the community. Results: A total of 655 respondents (218 cases and 437 controls) participated in the study. In multivariate analysis, being illiterate (adjusted odds ratio [AOR] 3.65, 95% confidence interval [CI] 2.31-5.76), households containing more than four family members (AOR 3.09, 95% CI 2.07-4.61), living space <4 m(2) per person (AOR 3.11, 95% CI 2.09-4.63), a nonseparated kitchen (AOR 3.27, 95% CI 1.99-5.35), history of contact with a TB patient (AOR 2.05, 95% CI 1.35-3.12), a house with no ceiling (AOR 1.46, 95% CI 1.07-2.21), and absence of windows (AOR 4.42, 95% CI 2.46-7.95) were independently associated with the development of TB. Conclusion: This study identified that the number of family members in the household, educational status, room space per person, history of contact with a TB patient, availability and number of windows, location of kitchen facilities within the house, and whether or not the house had a ceiling were independently associated with contracting TB. Every community should construct houses with the kitchen separated from the main living room, and include a ceiling and more than one window. Cigarette smoking should be avoided since this also contributed to the risk of transmission of TB. Further research focusing on coinfection with human immunodeficiency virus, helminth burden, and malnutrition is important for the control and prevention of TB.