The Decline of Tuberculosis Burden in Vietnam: A Comparison of Two Consecutive National Surveys

Abstract

Background: Despite interventions, the global tuberculosis epidemic has shown only modest declines in recent years. However, estimates of burden for most high-burden countries are based on indirect methods. Vietnam, a tuberculosis high-burden country, conducted national tuberculosis prevalence surveys in 2007 and 2017 to directly estimate its tuberculosis burden and evaluate the impact of tuberculosis control interventions during the interval. In this study, we compared the prevalence of tuberculosis between the two surveys based on analogous methods. Method: Participants in both surveys were screened for TB by a questionnaire and chest X-ray. Individuals with a positive screening result were asked to provide sputum samples to test for Mycobacterium tuberculosis by light microscopy using direct Ziehl-Neelsen-stained smear and Lowenstein–Jensen solid culture. Culture-positive TB, smear-positive TB, and smear-negative TB cases were defined by microscopy and culture results. Findings: The prevalence of culture-positive TB decreased by 37% (11·5-55·4%), from 199 (160-248) per 100,000 adults in 2007 to 125 (98-159) per 100,000 adults in 2017. The prevalence of smear-positive TB dropped by 53% (27·0-69·7%), from 99 (78-125) per 100,000 adults to 46 (32-68) per 100,000 adults, while smear-negative TB showed no significant reduction. Interpretation: The burden of TB has reduced considerably in Vietnam in the last decade, with a shift from smear-positive to smear-negative disease. To further lower the TB burden, diagnosis should focus on identifying all pulmonary TB cases by replacing microscopy with molecular methods as the primary diagnostic method. Funding Statement: This study was funded by the Vietnam Ministry of Health, the The Global Fund to Fight AIDS, Tuberculosis and Malaria, the U.S. Agency for International Development, the US Centers for Disease Control and Prevention - Vietnam Office (CDC), the KNCV Tuberculosis Foundation, and the World Health Organization (WHO). Declaration of Interests: We declare no competing interests. Ethics Approval Statement: This study has been given scientific and ethical approval by the Institutional Review Board of the Vietnam National Lung Hospital, under approval letter number 62/17/CTHĐKH-ĐĐ. All participants were explained about the risks and benefits of the study and signed an individual written informed consent. All of those with at least one positive test for TB were referred for TB treatment and followed up to verify that they received adequate healthcare and treatment.