Pre-entry, post-entry, or no tuberculosis screening?
Authors: Marieke J van der Werf, Knut Lönnroth
Journal: The Lancet Infectious Diseases (2014)

In The Lancet Infectious Diseases, Robert Aldridge and colleagues1Aldridge RW Yates TA Zenner D White PJ Abubakar I Hayward AC Pre-entry screening programmes for tuberculosis in migrants to low-incidence countries: a systematic review and meta-analysis.Lancet Infect Dis. 2014; (published online Nov 7.)http://dx.doi.org/10.1016/S1473-3099(14)70966-1Google Scholar report the results of a systematic review on pre-entry screening for tuberculosis. They conclude that it should be considered as part of a broad package of activities for tuberculosis care, prevention, and control in migrants. Pre-entry screening refers to screening of people who intend to migrate—ie, before they leave their country of origin. Alternative strategies include upon-entry or post-entry screening. Because in many countries with a low incidence of tuberculosis a high proportion of the burden of tuberculosis is present in foreign-born people with tuberculosis,2European Centre for Disease Prevention and ControlWHO Regional Office for EuropeTuberculosis surveillance and monitoring in Europe, 2014. European Centre for Disease Prevention and Control, Stockholm2014Google Scholar there is a lively debate on whether screening should be implemented and, if so, what approach should be used.3Moore-Gillon J Davies PD Ormerod LP Rethinking TB screening: politics, practicalities and the press.Thorax. 2010; 65: 663-665Crossref PubMed Scopus (23) Google Scholar A recent WHO guideline includes a conditional recommendation (based on very low-quality evidence) for systematic screening for active tuberculosis in subpopulations that have very high tuberculosis rates or very poor access to health care, such as some migrants and refugees residing in, or coming from, settings with a high prevalence of tuberculosis. The guideline stresses the need to prioritise only groups with very high risk.4WHOSystematic screening for active tuberculosis: principles and recommendations. World Health Organization, Geneva2013Google Scholar With the exception of some refugees, migrants are usually not a risk group in their country of origin, but might be deemed a high-risk group from the perspective of the receiving country. Unsurprisingly, Aldridge and colleagues report that the yield of pre-entry screening for tuberculosis is strongly correlated with the tuberculosis incidence in the country of origin.1Aldridge RW Yates TA Zenner D White PJ Abubakar I Hayward AC Pre-entry screening programmes for tuberculosis in migrants to low-incidence countries: a systematic review and meta-analysis.Lancet Infect Dis. 2014; (published online Nov 7.)http://dx.doi.org/10.1016/S1473-3099(14)70966-1Google Scholar This correlation is the same for post-entry screening.5Erkens C Slump E Kamphorst M et al.Coverage and yield of entry and follow-up screening for tuberculosis among new immigrants.Eur Respir J. 2008; 32: 153-161Crossref PubMed Scopus (55) Google Scholar Countries use different tuberculosis incidence thresholds to define from which countries of origin migrants should be screened.6Pareek M Baussano I Abubakar I Dye C Lalvani A Evaluation of immigrant tuberculosis screening in industrialized countries.Emerg Infect Dis. 2012; 18: 1422-1429Crossref PubMed Scopus (85) Google Scholar Thus, the quantification of the yield in migrants from different countries of origin provided by Aldridge and colleagues is important to guide prioritisation of countries of origin to focus the screening. Only a few low-incidence countries undertake pre-entry tuberculosis screening.6Pareek M Baussano I Abubakar I Dye C Lalvani A Evaluation of immigrant tuberculosis screening in industrialized countries.Emerg Infect Dis. 2012; 18: 1422-1429Crossref PubMed Scopus (85) Google Scholar As Aldridge and colleagues report, the cost-effectiveness of pre-entry screening, but also of post-entry screening, is unknown. More importantly, there are few data on the effect of any type of migrant tuberculosis screening on tuberculosis epidemiology.7Kranzer K Afnan-Holmes H Tomlin K et al.The benefits to communities and individuals of screening for active tuberculosis disease: a systematic review.Int J Tuberc Lung Dis. 2013; 17: 432-446Crossref PubMed Scopus (186) Google Scholar Also, the claim that migrant screening is done to protect the health of the autochthonous population has not been substantiated by proof that there is substantial transmission from migrants to the native population that can be prevented by screening.8Sandgren A Schepisi MS Sotgiu G et al.Tuberculosis transmission between foreign- and native-born populations in the EU/EEA: a systematic review.Eur Respir J. 2014; 43: 1159-1171Crossref PubMed Scopus (71) Google Scholar Even though evidence is weak, in view of the aim to eliminate tuberculosis as a public health problem, migrant screening in low-incidence countries might be considered after a careful epidemiological assessment, coupled with detailed monitoring and assessment.9WHOTowards tuberculosis elimination: an action framework for low-incidence countries. World Health Organization, Geneva2014Google Scholar Pre-entry screening is conventionally financed out-of-pocket by visa applicants, whereas treatment is paid either out-of-pocket, by health insurance, or by a national tuberculosis programme. Therefore, cost savings might be associated with pre-entry screening for the receiving country, by reduction of screening and treatment costs after arrival. Shifting costs to the country of origin could reduce overall cost from an international societal perspective because health care costs are normally much higher in the receiving country. However, financial burden, equity, and ethics need to be considered, including the risk of stigma and discrimination. The countries discussed in the report grant visas after completion of tuberculosis treatment. However, some other countries use pre-entry screening to unconditionally refuse entry even if screen-positive individuals were to be treated before migration—a discriminatory approach without any epidemiological rationale.10Wickramage K Mosca D Can migration health assessments become a mechanism for global public health good?.Int J Environ Res Public Health. 2014; 11: 9954-9963Crossref PubMed Scopus (26) Google Scholar, 11Kronfol NM Mansour Z Tuberculosis and migration: a review.East Mediterr Health J. 2013; 19: 739-748PubMed Google Scholar When doing pre-entry screening it is important to establish good collaboration and data sharing with the disease control agency in the country of origin. Setting up good laboratory facilities and ensuring high standards of tuberculosis diagnosis and treatment are essential, and can benefit the country of origin. It has also been shown that by helping to improve the overall tuberculosis control approaches in high-incidence countries from which many of their migrants originate, receiving countries can deliver cost savings.12Schwartzman K Oxlade O Barr RG et al.Domestic returns from investment in the control of tuberculosis in other countries.New Engl J Med. 2005; 353: 1008-1020Crossref PubMed Scopus (138) Google Scholar We agree with Aldridge and colleagues that pre-entry screening is only one potential element of a strategy to improve tuberculosis care and prevention for migrants. Full health care access post-migration is the first priority. Strategies need to cover the full continuum of tuberculosis prevention and care pre-migration and post-migration, including support to global tuberculosis control and addressing underlying determinants of tuberculosis.9WHOTowards tuberculosis elimination: an action framework for low-incidence countries. World Health Organization, Geneva2014Google Scholar We declare no competing interests. Both authors contributed equally. Pre-entry screening programmes for tuberculosis in migrants to low-incidence countries: a systematic review and meta-analysisTargeting high-prevalence countries could result in the highest yield for active disease. Pre-entry screening should be considered as part of a broad package of measures to ensure early diagnosis and effective management of migrants with active tuberculosis, and be integrated with initiatives that address the health needs of migrants. Full-Text PDF Open Access