Screening for tuberculosis (TB) in Britain is failing to detect most imported
cases of latent disease. This suggests the need that screening should be
widened to include more people from the Indian subcontinent. The current
screening policy is missing 70% of imported latent TB cases.
The current British border policies require immigrants to have a chest X-ray
on arrival to check for active TB. This policy is applicable for people hailing
from countries with a TB incidence higher than 40 per 100,000 people and covers
African countries but has excluded Asian countries like India, Pakistan and
Bangladesh. It has been seen that only 0.01% immigrants have active TB on
arrival. Majority of them are carriers of the latent disease and within few
years of their arrival in Britain it progresses to active TB.
Demographic and test result data from 2008 to 2010 at 3 immigrant screening
centers in Britain were analyzed to check the efficacy of the screening. For detecting
latent tuberculosis researchers used a highly specific blood test called an
interferon-gamma release assay (IGRA). The results showed that 20% of recent
immigrants from the Indian sub-continent and almost 30% from sub-Saharan Africa
are carriers of latent TB.
The study is published in The Lancet
Infectious Diseases journal.