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Setting: Six provinces in Vietnam where the DOTS strategy was introduced in 1989., Objective: To assess the impact of improved tuberculosis (TB) control on TB epidemiology in Vietnam., Methods: Data from the surveillance system in the period 1990-2003 were analysed to assess trends of notification rates and the mean ages of notified cases. Data from repeated tuberculin surveys in the period 1986-2002 were estimated to assess the prevalence of TB infection, the annual risk of infection and its trend using various cut-off points in those with and without bacille Calmette-Guérin (BCG) scar., Results: Age-standardised notification rates in the period 1996-2003 declined significantly, by 2.6% to 5.9% per year, in five provinces. However, in four provinces notification rates in the age group 15-24 years increased significantly, by 4.5% to 13.6% per year, during this period. The mean age of newly diagnosed patients with smear-positive TB increased up to 1995 but decreased thereafter. The annual risk of TB infection showed a significant annual decrease (4.9% per year) in one province in surveys performed between 1986 and 1997, and in two provinces (6.6% and 4.7%) in surveys conducted between 1993 and 2002., Conclusion: These data suggest limited impact to date of the DOTS strategy in Vietnam.

Objective: To assess the yield of sputum smear microscopy and sex differences in the National Tuberculosis Control Programme in the north of Vietnam., Methods: Review of registers of 30 randomly selected laboratories (26 district, 4 provincial level)., Results: The average daily workload per technician was 4.4 examinations in district and 5.3 examinations in provincial laboratories. To find one smear-positive case, 9.7 suspects were examined and 29.3 smears done. The smear-positive rate (mean 10.3%) was higher among men (11.6%) than among women (8.4%, P < 0.001). There were more men than women among tuberculosis (TB) suspects (male:female ratio 1.36, 95%CI 1.19-1.54), but even more so among smear-positive patients (1.89, 95%CI 1.64-2.14), irrespective of specimen quality and number of smears examined. Three smears were examined for 18,055 suspects (61.7%). The incremental gain was 33.5% and 4.9% for the second and third smear examination, respectively; 186 (95%CI 160-221) smears needed to be examined to find one additional case of TB with a third serial examination., Conclusion: The diagnostic process seemed generally efficient. The male:female ratios suggest higher TB incidence in men rather than lower access to TB facilities for women. The third smear examination could be omitted.

Objective: To describe the establishment and development of the National Tuberculosis Control Programme (NTP) of Vietnam., Methods: Data were obtained from the surveillance system established by the new NTP in 1986 and based on the principles now described as the WHO DOTS strategy., Results: The proportion of districts covered by the NTP increased from 40% in 1986 to almost 100% in 2000. The proportion of communes applying NTP guidelines increased from 18% in 1986 to 99.8% in 2000. The total number of tuberculosis cases notified increased from 8737 in 1986 to 89 792 in 2000. Most of these are new smear-positive cases. Based on WHO estimations of the incidence rate, the proportion of new smear-positive cases detected and put on short-course treatment has been over 70% since 1996. Reported cure rates with short-course chemotherapy are consistently over 85%., Conclusions: DOTS is feasible in a low-income, high-burden country. The main reasons for success were political commitment, a well-functioning health network, integration of tuberculosis control into the general health service at district level, a continuous supply of drugs and effective external support. Major challenges are long-term financial support, expansion to remote areas and vulnerable groups, definition of the role of the private sector, and future developments of the HIV epidemic and multidrug resistance.

Objective: To determine whether elimination of tuberculosis in the Dutch population can be achieved by the year 2030, taking into account the impact of immigration., Methods: The incidence of tuberculosis (all forms) in the period 1970 to 2030 was estimated using a life-table model for the Dutch population without the impact of immigration. The influence of immigration on tuberculosis incidence among the Dutch was modelled using four immigrant scenarios, distinguished by the assumed contact rate between immigrants and the Dutch population, and by different projections (middle, upper) of the future size of the immigrant population in The Netherlands., Results: The incidence of smear-positive tuberculosis among the Dutch is projected to be 1.4 per million in the scenario without the influence of immigrant cases, and ranging from 3.8 to 11.8 per million in the four immigrant scenarios. In all immigrant scenarios, the prevalence of tuberculosis infection will continue to decline and be less than 1% by the year 2030. At least 60% of Dutch tuberculosis cases in the year 2030 are expected to be the result of transmission from a foreign source case., Conclusion: Using a prevalence of tuberculosis infection of less than 1% as the elimination criterion, tuberculosis will probably be eliminated from the indigenous Dutch population by 2030. However, the incidence of smear-positive tuberculosis is expected to remain higher than 1 per million, and the majority of new tuberculosis cases among the Dutch may be attributable to recent infection from a foreign source case.

Setting: Tuberculin surveys of children to estimate national or regional infection prevalences are commonly designed as multi-stage surveys. These surveys require strategies for the efficient sampling of sub-units at each stage., Objectives: To develop guidelines for sampling in tuberculin surveys., Design: Sampling theory was used to develop a simple and efficient sampling strategy for planning and analysing tuberculin surveys. The issue of sample sizes is considered., Results: Formulae for the calculation of infection prevalences and their confidence intervals are developed. Sample sizes are discussed., Conclusion: We recommend that districts be sampled using sampling proportional to size, in which larger units have a larger probability of being included in the sample. Schools are sampled next using simple random sampling, where each school within a district has the same probability of being included in the sample. In each school all eligible children are Mantoux tested. The number of children tested per district should be approximately constant. Increasing the number of selected districts is usually more efficient for increasing the precision of the estimate than increasing the number of children per district beyond several hundred to a few thousand.

Setting: In the period 1950 to 1980 the risk of tuberculous infection in the Netherlands declined more steeply than tuberculosis incidence. This study aimed at determining whether this might be explained by preferential transmission within age groups., Methods: Using restriction fragment length polymorphism (RFLP) typing on all Mycobacterium tuberculosis isolates in the Netherlands from 1993 to 1996, clusters with identical fingerprints were identified. The correlation between the ages of people in clusters of two Dutch patients was determined., Results: The mean difference in age between the two people, in 81 clusters of two, was 13.9 years, while the mean age difference between all possible pairs of individuals in this data set was 25.5 years. Fisher's intraclass correlation coefficient was 0.62 (95% confidence interval [CI] 0.46-0.74)., Conclusion: It is concluded that sources of tuberculosis may preferentially transmit infection to people close to their own age. As the average age of cases has increased in the period 1950-1980, sources may have become less likely to infect children in whom the risk of infection has been measured. The annual risk of infection measured in children and young adults in countries with low levels of tuberculosis may not apply to older members of the population.