At-risk migrants show high rates of TB after migration

Migrants who were at risk for tuberculosis demonstrated a high rate of disease after migration, suggesting that preventive treatment for latent infection, improved pre-migration screening and post-migration follow-up would improve tuberculosis control in countries with low incidence, according to researchers in Australia.

“The WHO post-2015 End TB strategy seeks to reduce tuberculosis deaths by 95%, incident cases by 90% and tuberculosis-related morbidity between 2015 and 2035,” Claudia C. Dobler, MD, PhD, of the department of respiratory medicine at Liverpool Hospital, Sydney, and colleagues wrote. “In 2014, 66%, 73% and 27% of new TB cases in the U.S., the U.K. and the European Union, respectively, occurred in foreign-born persons. The rate of active tuberculosis post-migration in migrants identified to be at increased risk of developing tuberculosis on the basis of pre-migration abnormalities has not been evaluated in a systematic manner.”

The researchers performed a systematic review and meta-analysis of 20 studies on 8,355,030 migrants who were processed between Jan. 1, 1981, and May 1, 2014. All of the studies reported pre-migration screening results, identifying 222,375 migrants at high risk for TB.

Overall, cumulative incidence of TB from a pool of 22 cohorts was 2,794 cases per 100,000 persons (95% CI; 2,179-3,409), Dobler and colleagues wrote. At the first follow-up doctor’s visit from 10 cohorts, the incidence was 3,284 per 100,000 (95% CI; 2,173-4,395). Among 15 cohorts, the pooled incidence was 1,249 per 100,000 person-years of follow-up (95% CI; 924-1,574), according to Dobler and colleagues.

The researchers noted that these rates were significantly higher than TB rates in migrant-receiving countries (3 per 100,000 per year in the U.S.; 12.3 per 100,000 per year in the U.K., 5.5 per 100,000 per year in Australia; 4.4 per 100,000 per year in Canada).

“This study is new and important, showing the vulnerability of high-risk migrants and the need for systematic post-migration screening, eventually complementing a more sensitive pre-migration one,” Giovanni Sotgiu, MD, of the department of biomedical sciences at the University of Sassari, Italy, and Giovanni Battista Migliori, MD, of the WHO Collaborating Centre for TB and Lung Diseases, Tradate, Italy, wrote in an accompanying editorial. “More needs to be known about the cost-effectiveness and advantages of the various screening approaches available. Nevertheless, this study should stimulate all recipient countries to develop improved tuberculosis screening of migrants within sensitive health systems, respecting human rights and preventing stigma. Only by efficient screening and treatment of migrants on arrival will the general population be protected from rising tuberculosis incidence.” – by Andy Polhamus

Disclosure: Migliori and Sotgiu report no relevant financial disclosures. The researchers report no relevant financial disclosures.