Characteristics of migrants to Japan with TB and implications for pre-migration TB screening

Abstract

Abstract Background Japan plans to introduce pre-entry tuberculosis (TB) screening for those traveling from the Philippines, China, Vietnam, Nepal, Indonesia, and Myanmar, who are intending to stay in Japan for more than 90 days, in 2020. According to its screening algorithm, migrants will be screened by chest X-ray and those with abnormal findings will be asked to undergo sputum testing. We analyzed the characteristics of foreign-born TB patients coming from the above six countries, to identify some potential issues. Methods Data on foreign-born patients who had been newly notified with active pulmonary TB (PTB) in 2018 and 2017, and who had entered Japan in the same year they were notified, was extracted from the Japan TB Surveillance system. We assumed that these patients approximated to those hypothetical migrants who would be detected by pre-entry TB screening, and analyzed them by basic socio-demographic characteristics, radiological findings, and bacteriological test results. Results In 2017 and 2018, a total of 1,915 foreign-born PTB patients were notified from the above six countries. Of them, 19.9% (n = 381) had entered Japan in the same year they were notified. Among the 381, 23.9% (n = 50) had cavitary lesion, 27.3% (n = 57) were smear positive, and 48.9% (n = 73) were culture positive. 34.4% (n = 72) were both smear and culture negative, and the diagnosis would have depended on radiographical presentation. However, among the 72, the majority i.e. 87.5%, presented with non-cavitary pulmonary involvement. Conclusions Considering that approximately a third of TB patients who would may detected by the pre-entry screening are likely to be bacteriologically negative, Japan must ensure that the clinics conducting the pre-entry TB screening have access to high-quality radiography with expert interpretations, such as teleradiology and computer-assisted reading. Key messages A third of TB patients who would may detected by the pre-entry screening are likely to be bacteriologically negative. It is critical that clinics conducting screening have access to high-quality radiography with expert interpretations, such as teleradiology and computer-assisted reading.