]High TB Rates Persist in Somali Immigrants in Denmark

In many countries with a low incidence of tuberculosis (TB), most TB cases now occur in foreign-born residents. Understanding TB epidemiology in immigrant groups is essential for developing effective control programs. Danish researchers conducted a nationwide retrospective cohort analysis using surveillance data to assess the rates of active TB from 1991 to 1999 in Somali immigrants by duration of residence in Denmark, where 57.5% of reported TB cases during this period were in foreign-born residents.

During these years, 901 Somalis were reported with active TB, accounting for 37.8% of the TB cases reported in foreign-born residents. Active TB was diagnosed in almost 4% of Somali immigrants during their first 2 years living in Denmark; the cumulative proportion increased to 9.5% after 7 years. Annual incidence rates ranged from 0.7% to 2.0% and showed little decline during the study period. An earlier skin-test survey had found that 80% to 90% of Somali adults had evidence of TB infection. Currently, preventive therapy after positive tuberculin skin tests is given routinely only to children 7 years and younger. HIV infection apparently did not account for the high TB incidence, because only 1 to 2 Somali TB patients each year are found to be HIV-positive.

Comment: Unlike several earlier studies that suggest that most reactivation TB in immigrants occurs shortly after arrival in low-incidence areas, this study found continued high rates of active infection over at least 7 years. These results suggest the need to reassess current strategies, which in most low-incidence countries involve screening for active TB only at the time of entry into the country. At the time of publication, the full text of the original article was available at http://www.cdc.gov/ncidod/eid/vol8no7/01-0482.htm free of charge.