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Abstract Background Tuberculosis (TB) has been a major public health problem in South Korea. Although TB notification rate in Korea is gradually decreasing, still highest among the member countries of the Organization for Economic Cooperation and Development. To effectively control TB, understanding the TB epidemiology such as prevalence of latent tuberculosis infection (LTBI) and annual risk of TB infection (ARI) are important. This study aimed to identify the prevalence of LTBI and ARI among South Korean health care workers (HCWs) based on their interferon-gamma release assays (IGRA). Methods This was single center, cross-sectional retrospective study in a tertiary hospital in South Korea. We performed IGRA in HCWs between May 2017 and March 2018. We estimated ARI based on IGRA results. Logistic regression model was used to identify factors affecting IGRA positivity. Results A total of 3233 HCWs were analyzed. Median age of participants was 38.0 and female was predominant (72.6%). Overall positive rate of IGRA was 24.1% and IGRA positive rates age-group wise were 6.6%, 14.4%, 34.3%, and around 50% in the age groups 20s, 30s, 40s, and 50s and 60s, respectively. The ARIs was 0.26–1.35% between 1986 and 2005; rate of TB infection has gradually decreased in the last two decades. Multivariable analysis indicated that older age, healed TB lesion in x-ray, and male gender were risk factors for IGRA positivity, whereas working in high-risk TB departments was not. Conclusions Results showed that ARI in South Korean HCWs gradually decreased over two decades, although LTBI remained prevalent. Our results suggest that the LTBI test result of HCWs might be greatly affected by age, rather than occupational exposure, in intermediate TB burden countries. Thus, careful interpretation considering the age structure is required.

OBJETIVO: Estudar o risco anual da infecção tuberculosa na população escolar e residente no Distrito Federal, em 1997. METODOLOGIA: Trata-se de um estudo transversal, realizado com escolares das cidades de Ceilândia e Guará, no Distrito Federal. Foram estudadas 1.328 crianças. Para levantar a prevalência foi aplicado o modelo de ten Dam & Ritze e o risco anual, o método sugerido por Ruffino-Netto. O banco e a apuração dos dados foram executados utilizando-se o software Excel and SPSS 9.0. Na análise estatística, foram aplicados o teste do Qui-quadrado e o Intervalo de Confiança. Houve aprovação do estudo pela Comissão de Ética em Pesquisa e, foi solicitada dos responsáveis pelas crianças a assinatura do Termo de Consentimento Livre e Esclarecido. RESULTADOS: As proporções dos infectados e dos não-infectados pelo Mycobacterium tuberculosis nas duas cidades não diferiam estatisticamente (chi2=3,8416). Verificou-se que as crianças residentes, com idade de oito anos, apresentavam uma prevalência de tuberculose de 3,3% e, um risco anual de 0,42%, em 1997. CONCLUSÃO: Os resultados apontaram uma redução do RI no Distrito Federal. A partir dessas informações, a área pode ser caracterizada como sendo de média intensidade para a infecção tuberculosa e com tendência de melhora na situação.OBJECTIVE: To study the annual risk of tuberculosis infection among school age children resident in the Federal District, during 1997. METHODOLOGY: A cross-sectional study was carried out among 1,328 eight-year-old students, living in the cities of Ceilândia and Guará, in the Federal District, utilizing the Dam & Ritze model to determine prevalence rates and the method suggested by Ruffino-Netto for the annual risk. The data collected was processed using Excel and SPSS 9.0 software. Statistical analysis included Confidence Intervals and Chi-squares. The study was approved by the Ethics Research Committee, which requested that the adults responsible for the children signed a Term of Free and Full Consent. RESULTS: The proportions of those infected and non-infected by Mycobacterium tuberculosis did not differ statistically (chi2=3.8416) in the two cities. For 1997, the prevalence of tuberculosis was 3.3% and the annual risk of infection was 0.42% for the children studied. CONCLUSION: The authors expected to find a reduction in the IR in the Federal District. Based on this information, the area can be characterized as of medium intensity for tuberculosis infection but with a tendency towards the improvement in the epidemic.

Objetivo: Conocer la prevalencia de la infección tuberculosa y el riesgo anual de infección en la población escolar de Ceuta. Método: Estudio transversal. Se realizó la prueba de la tuberculina (2UT RT-23 Tween 80) a los niños de 7 años de edad escolarizados en Ceuta en 2008. Se consideraron positivos los niños no vacunados con una induración >5mm a las 72 horas. Resultados: Se estudiaron 612 niños. La prevalencia de la infección fue del 0,98% (intervalo de confianza del 95%, margen de error del 2,5%). Su distribución mostró diferencias entre las tres zonas de salud, y fue mayor en las zonas más deprimidas, donde llegó al 2,07%. El riesgo anual de infección fue del 0,15%. Conclusiones: La prevalencia de la infección es de las más altas de España, según los últimos estudios realizados. Los resultados no se corresponden con los datos epidemiológicos de tuberculosis de Ceuta, al tener en cuenta los casos importados.Objective: To determine the prevalence of tuberculosis infection and annual risk of infection in the school population of Ceuta. Method: A cross-sectional study was conducted. A tuberculin test (2UT RT-23 Tween 80) was given to 7-year-old schoolchildren in Ceuta in 2008. A positive result was considered as an induration of >5mm at 72hours in unvaccinated children. Results: A total of 612 children were studied. The prevalence of tuberculosis infection was 0.98% (95% confidence interval with a 2.5% margin of error). The distribution showed differences among three health areas, and was greatest in the most deprived area (2.07%). The annual risk of infection was 0.15%. Conclusions According to the most recent studies, the prevalence of tuberculosis infection in Ceuta is one of the highest of Spain. Our results do not agree with the epidemiological data for tuberculosis in Ceuta, which also includes imported cases.

Objective To estimate the change in annual risk of tuberculosis infection (ARTI) in two neighbouring urban communities of Cape Town, South Africa with an HIV prevalence of approximately 2%, and to compare ARTI with notification rates and treatment outcomes in the tuberculosis (TB) programme. Methods In 1998–1999 and 2005, tuberculin skin test surveys were conducted to measure the prevalence of Mycobacterium tuberculosis infection and to calculate the ARTI. All 6 to 9-year-old children from all primary schools were included in the survey. Notification rates and treatment outcomes were obtained from the TB register. Results A total of 2067 children participated in the survey from 1998 to 1999 and a total of 1954 in 2005. Based on a tuberculin skin test cut-off point of 10 mm, the ARTI was 3.7% (3.4–4.0%) in the 1998–1999 survey and 4.1% (3.8–4.5%) in 2005. The notification rate for pulmonary TB increased significantly from 646 per 100 000 in 1998 to 784 per 100 000 in 2002. In Ravensmead, there was no significant change in ARTI [first survey: 3.5% (3.1–3.9%), second survey: 3.2% (2.9–3.6%)], but in Uitsig the ARTI increased significantly from 4.1% (3.6–4.6%) to 5.8% (5.2–6.5%). The difference in ARTI between the two areas was associated with differences in reported case rates and the proportion of previously treated cases. Conclusion Tuberculosis transmission remains very high in these two communities and control measures to date have failed. Additional measures to control TB are needed. [ABSTRACT FROM AUTHOR]

Background: Tuberculosis has been declining in developed countries for a long time, as a result of the intrinsic epidemiological characteristics of this disease, combined with improvement in the standard of living and more recently the use of antibiotics. In these low prevalence countries, decisions concerning the objectives of tuberculosis programmes have to be taken and the consequences of short term changes in the sanitary situation have to be assessed.Methods: A deterministic model, without age structure, of the dynamics of pulmonary tuberculosis is proposed. The model extends that of Waaler and is intended to be more suitable for application to developed countries. The flows between seven subgroups of population, based on the natural history of the disease, are modelled and vaccination is taken into account. Values of model parameters and initial prevalences were deduced from published data.Results: As a first step, qualitative comparisons are performed between the model-predicted decline in the annual risk of infection (ARI) and data from the Netherlands tuberculosis survey. Using parameter values suited to France, our model shows that the predicted decline is slower in France than in the Netherlands; a result which tallies with epidemiological observations. Uses of the model as a decision tool are illustrated in two cases, that of ending systematic BCG vaccination and that of a sudden increase in the number of infectious cases. [ABSTRACT FROM AUTHOR]