Methods: Screening by chest X-ray/TAC and TST for every child (3-6 years), staff, and their contacts, was conducted. IGRA test (QFT in tube) was realized in all positive TST cases and PCR-MTBC and culture of sputum or gastric lavage if an abnormal radiology image was observed. Positive samples were analyzed by whole genome sequencing (WGS) for epidemiological investigation. Screening was repeated 8 weeks later in negatives for covering immunological window. Patients with LTI were considered if they presented any screening test positive, and recommended isoniazid treatment (IT). Demographic, clinical data and outcome were recorded.
Results: Overall, 240 children, 31 staff members and other 36 adults associated with the school were screened for TB. We detected 32 active TB cases (32/324, 9.87% children; 0/67, 0 % adults), and 83 LTI (29/324, 8.95% children; 54/67, 80.6% adults). Active TB cases were diagnosed by PCR-MTBC +/- culture of gastric lavage in 8 children, and by TAC in 27 (as well as all of them showed another positive screening test). Regarding patients with LTI, 51% of children (15/29) and 42.5% adults (23/54) were QFT+. The percentage of BCG vaccination was 4.9% in children and 28.3% in adults (only one QFT+). All TB cases completed treatment. IT was correctly taken by children but only by 63.3% of adults. Comparison by WSG of isolates from the teacher and all 8 children diagnosed in 2015 to the isolates from the child diagnosed in 2012 and an adult related with the nursery (not detected in the first screening) showed all of them belong to the same cluster.
Conclusion: This outbreak shows extensive transmission of TB among very young children and non vaccinated adults. Extended screening must be performed in the school when a child or an adult is diagnosed of TB.
M. J. Ruiz-Serrano, None
D. Garcia De Viedma, None
V. Vásquez, None
E. Bouza, None