Canadian Journal of Public Health

, Volume 109, Issue 1, pp 8–14 | Cite as

Prevalence of latent tuberculosis infection in Syrian refugees to Canada

  • Peter Warrington
  • Gregory Tyrrell
  • Kimberley Choy
  • Lisa Eisenbeis
  • Richard Long
  • Ryan CooperEmail author
Quantitative Research



Canada has accepted more than 25,000 Syrian refugees fearing persecution in their homeland. Canadian guidelines recommend screening recent refugees from high incidence countries for tuberculosis (TB) and latent TB infection (LTBI). The prevalence of TB in this population is unknown. A refugee clinic in Edmonton presented a unique opportunity to estimate prevalence of TB and LTBI in Syrian refugees arriving in Canada.


In January 2016, 100 consecutive Syrian refugees were screened for TB with clinical assessment and LTBI using QuantiFERON Gold In-Tube assay (QFT-GIT). Patients with positive QFT-GIT were referred to Edmonton Tuberculosis Clinic (ETBC) for evaluation and, if appropriate, offered prophylaxis.


No cases of active TB were found. Valid QFT-GIT were measured in 99 of 100 individuals and of these, nine (9%) were positive using a threshold concentration of blood interferon-γ greater than 0.35 IU/L. Eight of the nine patients attended follow-up appointments; of these, seven began LTBI prophylaxis and all seven (78%) completed same.


The 9% (95% confidence interval 3–15%) prevalence of LTBI was higher than expected in this population.


Latent tuberculosis Tuberculosis Refugees Syria 



Le Canada a accepté plus de 25 000 réfugiés syriens fuyant la persécution dans leur patrie. Les lignes directrices canadiennes recommandent le dépistage de la tuberculose et de la tuberculose-infection latente (TBIL) chez les réfugiés récents des pays à forte incidence. La prévalence de la tuberculose dans cette population est inconnue. Une clinique pour les réfugiés d’Edmonton a représenté une occasion unique d’estimer la prévalence de la tuberculose et de la TBIL chez les réfugiés syriens arrivant au Canada.


En janvier 2016, 100 réfugiés syriens de suite ont subi des tests de dépistage de la tuberculose avec évaluation clinique et de dépistage de la TBIL à l’aide du test QuantiFERON Gold In-Tube Assay (QFT-GIT). Les patients séropositifs selon le QFT-GIT ont subi une évaluation à la clinique de tuberculose d’Edmonton (ETBC) et, le cas échéant, se sont fait offrir une prophylaxie.


Aucun cas de tuberculose active n’a été décelé. Des épreuves QFT-GIT valides ont été réalisées chez 99 personnes sur 100, et neuf d’entre elles (9 %) ont affiché des résultats positifs, soit un seuil de concentration supérieur à 0,35 UI/l selon le test sanguin interféron gamma. Huit patients sur neuf se sont présentés aux rendez-vous de suivi, sept ont commencé un traitement contre la TBIL en prophylaxie, et tous les sept (78 %) l’ont terminé.


La prévalence de 9 % (intervalle de confiance de 95 %: 3–15 %) de la TBIL était plus élevée que prévu dans cette population.


Tuberculose latente Tuberculose Réfugiés Syrie 


Compliance with ethical standards

Ethics approval was provided by the University of Alberta Research Ethics Board.

Conflict of interest

The authors declare that they have no conflict of interest.


  1. American Academy of Pediatrics Red Book. (2009). Report of the Committee oen Infectious Diseases.
  2. Araj, G. F., Saade, A., Itani, L. Y., & Avedissian, A. Z. (2016). Tuberculosis burden in Lebanon: evolution and current status. Le Journal Médical Libanais, 64(1), 1–7 Accessed June 2, 2017.Google Scholar
  3. Barr, R. G., & Menzies, R. (1994). The effect of war on tuberculosis. Results of a tuberculin survey among displaced persons in El Salvador and a review of the literature. Tubercle and Lung Disease, 75(4), 251–259. Scholar
  4. Bennett, R. J., Brodine, S., Waalen, J., Moser, K., & Rodwell, T. C. (2014). Prevalence and treatment of latent tuberculosis infection among newly arrived refugees in San Diego County, January 2010-October 2012. American Journal of Public Health, 104(4), e95–e102. Scholar
  5. Bettache, N., Schwartzman, K., Cnossen, S., Sandoe A., Assayag D., Menzies D., Greenaway, C. (2012). Effectiveness of post-arrival latent tuberculosis screening programs in the foreign born: a systematic review and meta-analysis (abstract). Am J Respir Crit Care Med 185:2012A3325.
  6. Bodenmann, P., Vaucher, P., Wolff, H., et al. (2009). Screening for latent tuberculosis infection among undocumented immigrants in Swiss healthcare centres; a descriptive exploratory study. BMC Infectious Diseases, 9, 34. Scholar
  7. Campbell, J. R., Krot, J., Elwood, K., Cook, V., & Marra, F. (2015). A systematic review on TST and IGRA tests used for diagnosis of LTBI in immigrants. Molecular Diagnosis & Therapy, 19(1), 9–24. Scholar
  8. Centers for Disease Control and Prevention. (2010). Health of resettled Iraqi refugees San Diego County, California, October 2007-September 2009. MMWR. Morbidity and Mortality Weekly Report, 59(49), 1614–1618.Google Scholar
  9. Citizenship and Immigration Canada. (2015). Population Profile: Syrian Refugees. Published 2015. Accessed March 10, 2018.
  10. Cookson, S. T., Abaza, H., Clarke, K. R., et al. (2015). Impact of and response to increased tuberculosis prevalence among Syrian refugees compared with Jordanian tuberculosis prevalence: case study of a tuberculosis public health strategy. Conflict and Health, 9(1), 18. Scholar
  11. Gallant, V., Ogunnaike-Cooke, S., McGuire, M. (2014). Tuberculosis in Canada: 1924–2012. Canada Communicable Disease Report. 40–6. Published 2014. Accessed March 10, 2018.
  12. Greenaway, C., Khan, K., Schwartzman, K. (2013). Tuberculosis surveillance and screening in selected high-risk populations. In: Menzies D, ed. Canadian Tuberculosis Standards 7th Edition. 7th edn. Oakville: Pulsus; 2013:119-128Google Scholar
  13. Greenaway, C., Sandoe, A., Vissandjee, B., et al. (2011). Tuberculosis: evidence review for newly arriving immigrants and refugees. CMAJ, 183(12), 939–951. Scholar
  14. Houben, R. M. G. J., & Dodd, P. J. (2016). The global burden of latent tuberculosis infection: a re-estimation using mathematical modelling. PLoS Medicine, 13(10), 1–13. Scholar
  15. Immigration Refugees and Citizenship Canada. Who must submit to an immigration medical examination? Accessed July 3, 2016.
  16. Kimbrough, W., Saliba, V., Dahab, M., Haskew, C., & Checchi, F. (2012). The burden of tuberculosis in crisis-affected populations: a systematic review. The Lancet Infectious Diseases, 12(12), 950–965. Scholar
  17. Lewinsohn, D. M., Leonard, M. K., LoBue, P. A., et al. (2017). Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: diagnosis of tuberculosis in adults and children. Clinical Infectious Diseases, 64(2), e1–e33. Scholar
  18. Lönnroth, K., Migliori, G. B., Abubakar, I., et al. (2015). Towards tuberculosis elimination: an action framework for low-incidence countries. The European Respiratory Journal, 45(4), 928–952. Scholar
  19. Menzies, D., Alvarez, G., Khan, K. (2013). Treatment of latent tuberculosis infection. In: Menzies D, ed. Canadian Tuberculosis Standards 7th Edition. 7th edn. Oakville: Pulsus; 2013:44-53Google Scholar
  20. Pareek, M., Greenaway, C., Noori, T., Munoz, J., & Zenner, D. (2016). The impact of migration on tuberculosis epidemiology and control in high-income countries: a review. BMC Medicine, 14(1), 48. Scholar
  21. Pottie, K., Greenaway, C., Feightner, J., et al. (2011). Evidence-based clinical guidelines for immigrants and refugees. CMAJ, 183(12), E824–E925. Scholar
  22. Pottie, K., Greenaway, C., Hassan, G., Hui, C., Kirmayer, L. J. (2016). Caring for a newly arrived Syrian refugee family. CMAJ , 188(3), 207–211.
  23. Public Health Agency of Canada. (2015). Tuberculosis in Canada 2013 – Pre-release. Ottawa (Canada): Minister of Public Works and Government Services Canada. Published 2015. Accessed March 10, 2018.
  24. Rennert-may E, Hansen E, Zadeh T, Krinke V, Houston S, Cooper R. (2016). A step toward tuberculosis elimination in a low-incidence country: successful diagnosis and treatment of latent tuberculosis infection in a refugee clinic. Canadian Respiratory Journal Vol. 23(X).
  25. Sikora C. (2016). Screening tests for Syrian refugees. Alberta Health Service Bulletin. Published 2016. Accessed May 19, 2016.
  26. Styblo, K. (1980). Recent advances in epidemiological research in tuberculosis. Adv Tuberc Res Fortschritte der Tuberkuloseforschung Progrès l’exploration la Tuberc, 20, 1–63.Google Scholar
  27. Ting, W.-Y., Huang, S.-F., Lee, M.-C., et al. (2014). Gender disparities in latent tuberculosis infection in high-risk individuals: a cross-sectional study. PLoS One, 9(11), e110104e. Scholar
  28. World Health Organization. (2016a). Syrian Arab Republic Tuberculosis Profile. Published 2016. Accessed June 6, 2016.
  29. World Health Organization.(2016b). Iraq Tuberculosis Profile. 2016. Accessed June 6, 2016. 
  30. World Health Organization. (2016). Syrian Arab Republic: WHO and UNICEF estimates of immunization coverage. Published 2016. Accessed July 14, 2016.

Copyright information

© The Canadian Public Health Association 2018

Authors and Affiliations

  • Peter Warrington
    • 1
  • Gregory Tyrrell
    • 2
    • 3
  • Kimberley Choy
    • 4
  • Lisa Eisenbeis
    • 5
  • Richard Long
    • 1
    • 6
  • Ryan Cooper
    • 1
    Email author
  1. 1.Faculty of Medicine and DentistryUniversity of AlbertaEdmontonCanada
  2. 2.Department of Laboratory Medicine and PathologyUniversity of AlbertaEdmontonCanada
  3. 3.Provincial Laboratory for Public HealthAlberta Health ServicesEdmontonCanada
  4. 4.Public HealthAlberta Health ServicesEdmontonCanada
  5. 5.Edmonton Tuberculosis ClinicAlberta Health ServicesEdmontonCanada
  6. 6.School of Public HealthUniversity of AlbertaEdmontonCanada

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