Prevalence and annual risk of tuberculosis infection in Laos
OBJECTIVE: To estimate the prevalence (P) and annual risk of tuberculosis infection (ARTI) and relate this to case rates in the tuberculosis program.
METHODS: Tuberculin survey in schools in Vientiane municipality and three provinces. Sampling was not representative, but included schools in accessible districts in provinces with different characteristics. A group of 150 tuberculosis patients were tested for comparison.
RESULTS: An intra-dermal tuberculin test (PPD RT23/Tween80) was applied to 11 237 children; 9968 reactions were read, 4035 among first and second grade children with no BCG scar: 818 in Vientiane (mean age 8.4), 803 in Savannakhet (8.9), 1563 in Xiengkhuang (8.4), and 851 in Luangprabang (7.9). If reactions of ≥10 mm are counted, ARTI is estimated as 1.1% for the areas included in the survey with a strong variation by province (Vientiane 1.3%; Savannakhet 1.4%; Luangprabang 0.6%; Xiengkhuang 0.1%). The difference in ARTI is in accordance with differences in reported case rates in the provinces. The ARTI varied from 0.5% to 1.2%, depending on the method used for calculating P (Vientiane 0.6%–1.4%; Savannakhet 0.5–1.5%; Xiengkhuang 0.1%–0.2%; Luangprabang 0.4%–0.9%).
CONCLUSIONS: The ARTI is unequally distributed geographically and/or by ethnic group. It is generally higher in south and lower in central and north Laos. Improved methods are needed for estimating the prevalence of infection.
Document Type: Regular Paper
Affiliations: 1: International Union Against Tuberculosis and Lung Disease, Paris, France 2: National Tuberculosis Program, Ministry of Health, Vientiane, Laos PDR 3: Damien Foundation, Brussels, Belgium
Publication date: 2001-05-01
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.
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