Description of the largest cluster of tuberculosis notified in Norway 1997–2011: is the Norwegian tuberculosis control programme serving its purpose for high risk groups?

Abstract

BackgroundApproximately 90% of new tuberculosis (TB) cases notified in Norway are asylum seekers and other immigrants from high-incidence countries. Asylum seekers are screened upon arrival at the National Immigration Centre. Other immigrants receive a letter from the Municipal Health Services requesting that they present for screening in their municipality of residence. In order to identify potential areas where the TB control programme could be better adapted for these groups, we studied the largest cluster of TB cases (“cluster X”) notified in Norway until 2011.MethodsCases were defined as TB notifications reported to MSIS between January 1997 and December 2011 with identical IS6110 RFLP assigned to cluster X. We described the cases in cluster X by using data from the Norwegian Surveillance System for Communicable Diseases (MSIS). Missing or incomplete information in MSIS was obtained from the National Reception Centre, Oslo University Hospital and Municipal Health services.ResultsOf a total of 44 individuals meeting the case definition, 36 originated from Somalia and eight from other high-incidence countries. Twenty nine were asylum seekers and 15 were other immigrants. Upon arrival, 18/44 had been diagnosed with latent TB infection (LTBI), 9/44 tested negative for LTBI and 4/44 had been diagnosed with active TB. Results of TB-screening upon arrival were not available for the remaining 13/44 (one asylum seeker and 12 other immigrants). Five of the 12 other immigrants had still not been screened for TB after staying one year or longer in Norway.ConclusionsMost cases in cluster X with available results of TB-screening were already infected at arrival, indicating that their disease could be due to endogenous reactivation, rather than recent transmission after arrival to Norway. TB-status upon arrival was unknown for many of the other immigrants due to lack of initial screening. The reasons why conduction of the initial screening among other immigrants is failing should be explored and methods to simplify the TB screening at arrival should be implemented.

A Predominant Variable-Number Tandem-Repeat Cluster of Mycobacterium tuberculosis Isolates among Asylum Seekers in the Netherlands and Denmark, Deciphered by Whole-Genome Sequencing

“…In Denmark, asylum seekers are offered health interviews and, in cases with symptoms, additional testing can be performed. It is assumed that most asylum seekers who develop disease after arrival are experiencing an endogenous reactivation rather than a new infection due to recent transmission after arriving in the destination country ( 3 , 18 ). Nevertheless, the possibility of transmission in the destination country remains.…”

“…The increase in immigrants from countries with higher TB incidences is also an important issue in other European countries with low incidences. In the Nordic countries, for instance, a considerable influx of immigrants, which has contributed significantly to the TB incidence in those countries, has been reported ( 3 – 6 ). In Denmark, for example, the overall TB incidence in 2015 was 6.3 cases per 100,000 inhabitants, with 75% of cases being of non-Danish origin; 19% of the cases were from the Horn of Africa ( 7 ).…”

Asylsøkeres helse og bruk av helsetjenester i Norge

“…Danielsen og kolleger modellerte effekten av å prioritere mellom screening av tuberkulose og meticillinresistente S. aureus (28). I to artikler tok man også for seg prediktive verdier ved ulike tester (29,30), og Guzman-Herrador og kolleger så på den største gruppen av tuberkulosegenotyper for å identifisere svakheter i screeningprogrammet (31).…”

Genome-based transmission modelling separates imported tuberculosis from recent transmission within an immigrant population

“…Here, we apply a novel approach to investigate whether immigrants diagnosed with TB represent imported cases or local transmission. We focused on a large genotypic M. tuberculosis cluster (Norwegian–African large Lineage 3 cluster; NAL3C), strongly associated with immigrants from the Horn of Africa, that has been identified in Norway consistently for almost 20 years [ 18 ]. Building on a temporal phylogeny reconstructed from genome-wide SNPs, we infer the posterior distribution of infection times using TransPhylo.…”