FRIDAY, Oct. 14, 2016 (HealthDay News) -- Migrants from countries with a high incidence of tuberculosis who undergo screening before entry to low-incidence countries pose a negligible risk of onward transmission but are at increased risk of the infection, according to a study published online Oct. 11 in The Lancet.
Robert W. Aldridge, Ph.D., from the Institute of Health Informatics at University College London, and colleagues examined a cohort of migrants screened for tuberculosis before entry to England, Wales, and Northern Ireland, and tracked disease development in this group. Data were included for 519,955 migrants from 15 countries with a high incidence of tuberculosis.
The researchers identified 1,873 incident cases of all forms of tuberculosis; the estimated incidence of all forms of tuberculosis in migrants screened before entry was 147/100,000 person-years. Migrants screened before entry had estimated incidence of 49/100,000 person-years for bacteriologically-confirmed pulmonary tuberculosis. Compared to those with no radiographic abnormalities, migrants whose chest radiographs were compatible with active tuberculosis but with negative pre-entry microbiological results were at increased risk of tuberculosis (incidence rate ratio, 3.2). There was a significant increase in the incidence of tuberculosis after migration with increasing World Health Organization-estimated prevalence of tuberculosis in migrants' countries of origin.
"Migrants from countries with a high incidence of tuberculosis screened before being granted entry to low-incidence countries pose a negligible risk of onward transmission but are at increased risk of tuberculosis," the authors write.
One author received research funding from Otsuka for a study of multidrug-resistant tuberculosis treatment.
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