The Prevalence and burden of pulmonary tuberculosis and latent tuberculosis in students

บทคัดย่อ

Introduction: Thailand is among the 30 countries with high tuberculosis (TB) burden listed by WHO. Cases of TB in Secondary schools have been reported. Nevertheless, studies of prevalence of TB diseases and latent TB infection (LTBI) in schoolchildren in Thailand are not limited.

Materials & Methods: We did an observational cross-sectional study in Secondary school children grade 7-12 in 2 schools, 1 in Bangkok and 1 in a province. We used the Symptoms scoring questionnaire developed by the Bureau of Tuberculosis and Chest radiography to screen for pulmonary TB. For LTBI, we used tuberculin skin test (TST) at a 10 mm. cut-off to identify LTBI in grade 7 students. Furthermore, results of TST among 80 students were compared with QuantiFERON^® TB Gold (QFT) blood test; and we did a survey on knowledge, attitude, and practice (KAP) of TB in school among personnel of the 2 schools using a structured questionnaire.

Results: Among 5,113 students from 2 schools 1,005 were enrolled; 496 from a school in Bangkok and 509 from a school in Chonburi province. Three hundred and fifty-four, 176, 154, 176, 141, and 153 students were from Grade 7, 8, 9, 10, 11 and 12 respectively. The mean age was 14.6 ±1.8 years. The percentages of schoolchildren with household incomes of 20,000-40,000 and less than 20,000 Thai Baht per month were 45.8 and 21.8; respectively. 20% had the history of TB exposure in the past. The screening with symptom scoring questionnaire and chest radiography revealed no TB disease in this survey. Meanwhile, 270 first grade students were screened for latent TB and 13 were positive, resulted in latent TB prevalence of 4.8% (95% Confidence Interval (CI), 2.3-7.4%) Of them, none developed TB disease during the 1-year follow-up. The TST at 10 mm. cut-off had the sensitivity 50% (95% CI 6.8-98.2) and specificity 98.7 (95% CI, 92.9-100%) compared to QFT. Furthermore, the results of KAP survey among the school personnel showed lower percentage (11-39%) of correct answers to knowledge of TB in children, transmission, and prevention of TB in community. Most personnel had positive attitude to learn about TB and help students to receive treatment (78-99%). However, 55% tended to separate students with TB from others even the students already receiving treatment and 29% would not be a personal tutor for students with TB after the treatment.

Conclusion & recommendation: The prevalence LTBI in the studied school children was less than 5% and no TB disease were found. The routine TB screening in Thailand schools may be less necessary than the other target population with higher TB rate. However, systematic implementation for reporting and full investigation should be put forward for schoolchildren who develop TB disease along with school personnel education on TB transmission and prevention.