Background: children residing in low-incidence countries of tuberculosis (TB) travelling abroad to endemic TB regions for visiting friends and relatives (VFR) are at risk of latent TB infection (LTBI). The identification of risk factors associated with TB infection would allow us to improve screening programmes pre-post travel. The aim of this study was to determine the incidence and risk factors associated with LTBI in VFR children travelling to countries with high-incidence of TB.

Methods: a multicentric prospective cohort study is being developed since 2017, including different health-care levels, of a cohort of VFR children <15-year-old travelling to high-incidence TB countries of >50 cases/105 inhabitants. Children were screened before travelling with a tuberculin skin test (TST), LTBI was defined as a TST conversion and/or a positive QuantiFERON-TB-Plus®(QFT) performed after the trip. Statistical analysis was carried out through Statav13. Ethical approval was obtained from all the participating centres. 

Results: two-hundred sixty-four children were recruited, 252 analysed (12 not TST-screened). Median[IQR] age was 5.83[2.84-9.02]years; 50.8% female; 86.7% autochthonous; 4.8% BCG-vaccinated; 41.3%(104/252) travelled to Africa, 36.9%(93/252) to Asia, 20.6%(52/252) to America/Caribbean, and 1.2%(3/252) to Eastern Europe. Median[IQR] travel duration was 1.3[1.0-1.8]months. TST was performed at a median[IQR] of 16[7-22]days before departure’s date; 4/252(1.6%;95%CI:0.6-4.2%) were TST positive: 3/252(1.2%;95%CI:0.4-3.6%) LTBI, and 1/252(0.4%) because of BCG vaccination. After travelling, among 187 children TST and/or QFT were performed in 74.9%(95%CI:68.1-80.6%) of them at a median[IQR] of 74[53-95]days, and no LTBI have been detected due to travel itself.     

Conclusions: no LTBI cases have been detected after travelling in these preliminary results. However, 3 children with LTBI (1.2%;95%CI:0.4-3.6%) were diagnosed due to the study itself before the trip. VFR children could be a high-risk group for LTBI susceptible to be screened.

INCIDENCE OF TUBERCULOSIS INFECTION IN CHILDREN TRAVELLING TO COUNTRIES WITH HIGH PREVALENCE OF TUBERCULOSIS (PRELIMINARY RESULTS)