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Free Content The bleach method improves the detection of pulmonary tuberculosis in Laos

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SETTING: Laos has a high prevalence of tuberculosis (TB) and a low prevalence of human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS). Mycobacterium tuberculosis culture is not yet available. Case finding is based on the microscopic detection of acid-fast bacilli (AFB) in sputum. Liquefaction and concentration using sodium hypochlorite (bleach) could improve its yield.

OBJECTIVE: To assess the gain due to the bleach method and its feasibility in Laos, and to compare the classical method sputum processing (direct microscopy) and the bleach method for AFB detection over 3 consecutive months at a central site (Vientiane) and for 1 month at a peripheral site (Attapeu).

RESULTS: Of 1675 sputum samples collected from 612 patients, respectively 206 (12.3%) and 275 (16.4%) were AFB-positive by the direct and bleach methods (P = 0.0007), i.e., an increase in smear positivity rate of 33.5% (95%CI 31.2–35.8). The superiority of the bleach method was confirmed, regardless of the site, the aspect of the sputum and delay before analysis. This method yielded 24 more TB patients.

CONCLUSION: The bleach method, which is very easy to use, could significantly increase the yield of sputum smear microscopy for the detection of pulmonary TB in Laos.

Keywords: case detection; microscopy; sodium hypochlorite; sputum; tuberculosis

Document Type: Regular Paper

Affiliations: 1: Institut de la Francophonie pour la Médecine tropicale, Vientiane, Lao Peoples' Democratic Republic 2: Service Fraternel d'Entraide, Hôpital d'Attapeu, Attapeu, Lao Peoples' Democratic Republic

Publication date: 2009-09-01

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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