Evaluation of Immigrant Tuberculosis Screening in Industrialized Countries

Manish Pareek, Iacopo Baussano, Ibrahim Abubakar, Christopher Dye, and Ajit Lalvani

Author affiliations: Imperial College London, London, UK (M. Pareek, A. Lalvani); University of Leicester, Leicester, UK (M. Pareek); Univeristà degli Studi del Piemonte Orientale, Novara, Italy (I. Baussano); University College London, London (I. Abubakar); University of East Anglia, Norwich, UK (I. Abubakar); and World Health Organization, Geneva, Switzerland (C. Dye)

Abstract

In industrialized countries, tuberculosis (TB) cases are concentrated among immigrants and driven by reactivation of imported latent TB infection (LTBI). We examined mechanisms used to screen immigrants for TB and LTBI by sending an anonymous, 18-point questionnaire to 31 member countries of the Organisation for Economic Co-operation and Development. Twenty-nine (93.5%) of 31 responded; 25 (86.2%) screened immigrants for active TB. Fewer countries (16/29, 55.2%) screened for LTBI. Marked variations were observed in targeted populations for age (range <5 age="age" all="all" and="and" countries="countries" groups="groups" immigrants="immigrants" in="in" incidence="incidence" of="of" origin="origin" tb="tb" to="to" years="years">20 cases/100,000 population to >500 cases/100,000). LTBI screening was conducted in 11/16 countries by using the tuberculin skin test. Six countries used interferon-γ release assays, primarily to confirm positive tuberculin skin test results. Industrialized countries performed LTBI screening infrequently and policies varied widely. There is an urgent need to define the cost-effectiveness of LTBI screening strategies for immigrants.

Tuberculosis (TB) in industrialized countries has reemerged as a public health concern after decreases in incidence during the 20th century. Over the past 30 years, although industrialized countries have shown country-specific quantitative changes (decrease, stabilization, or increase) in overall TB notifications, they share a similar underlying shift in TB epidemiology: decreasing incidence in the native population and an increasing incidence in foreign-born persons (1,2).
This disproportionate epidemiology is driven primarily by interaction of reactivating latent TB infection (LTBI) and high or increasing immigration levels. This interaction is demonstrated by the small proportion of clustered cases among foreign-born persons, which is lower than that among native-born persons, in molecular epidemiology studies from diverse industrialized settings (3). This interaction is also demonstrated by TB acquired before immigration and high or increasing levels of immigration from countries with a high incidence of TB in sub-Saharan Africa, Asia, South America, and northern Africa to industrialized countries that have a low incidence of TB (4,5).
Surveillance data from several industrialized countries show that a high proportion of active TB cases in foreign-born persons occurs in the first 5 years after arrival (new entrants) (6,7). The high level of foreign-born persons with TB in industrialized countries potentially jeopardizes national TB control programs and has reopened the debate about how industrialized, immigrant-receiving countries should screen immigrants (8,9). Although industrialized countries have national policies on immigrant screening, little contemporary comparison (10) of critical elements of these policies has been made.
We conducted an international evaluation of screening practices for TB among immigrants in industrialized countries. We also compared critical elements of national guidance, including whether screening identified cases of active TB or LTBI, which groups were targeted for screening, when screening was conducted, and which screening tools were used.