Screening della tubercolosi latente nei migranti: l'esperienza di Pavia

Background: Latent tuberculosis infection (LTBI) is a state of persistent bacterial viability, immune control, and no evidence of clinically manifested active tuberculosis, following the inhalation of Mycobacterium tuberculosis. In low-incidence countries, most tuberculosis (TB) cases occur among migrants and are caused by reactivation of LTBI acquired in the country of origin. However, diagnosis and treatment of LTBI are rarely implemented to reduce the burden of TB in immigrants. Material/methods: In September 2015, given the abrupt increase in the number of refugees reaching Italy, we have set up a LTBI screening clinic for refugees, migrants and contacts of active TB cases in our Department, in close collaboration with the Public Health service of Azienda Sanitaria Locale (ASL) of Pavia. Approximately 10 patients are seen every Monday and Tuberculin Skin Test (TST) is read every Thursday; those with a positive TST are screened with chest X-Rays and, in case of lesions suspected of TB nature, by induced sputum culture. Those having a positive sputum culture are diagnosed as having active TB infection and are therefore referred to the TB outpatient care for therapy and follow up; those having a positive TST but showing no positivity at chest X-Rays or sputum culture receive INH 300 mg daily for 6 months as prophylaxis for LTBI. This activity was undertaken at no extra cost for the Department, as part of the normal daily outpatient routine schedule. Here we report our data in patients seen from 21st September 2015 to 22th June 2016. Results: Out of 162 patients screened in the time period (coming from Nigeria, Bangladesh, Italy, Senegal, Pakistan, Mali, Romania, Ivory Coast, Afghanistan, Gambia, Ghana, Cameroon, Guinea, Somalia, Albania, Guinea Bissau, Burkina Faso, Ukraine, Peru, Sierra Leone, Benin) 43 (26.5%) had a positive TST (from Nigeria, Bangladesh, Mali, Senegal, Romania, Ivory Coast, Gambia, Guinea, Guinea Bissau, Pakistan, Peru). Among those, 4 (2.5%, from Nigeria, Romania, and Pakistan) also had active TB and were hospitalized and treated, while the other 39 received INH prophylaxis. Conclusions: Screening by means of TST has allowed to identify and treat 4 cases (2.5%) of active TB and 39 cases (24.1%) of LTBI in migrants, among whom 32 (82.1%) coming from countries with an incidence rate higher than 100 cases/year per 100000 people. All in all, our experience supports screening for LTBI in selected populations of immigrants.