Molecular genotyping of Mycobacterium tuberculosis has proved to be a powerful tool in tuberculosis surveillance, epidemiology, and control. Based on results obtained through 15 years of nationwide IS6110 restriction fragment length polymorphism (RFLP) genotyping of M. tuberculosis cases in Denmark, a country on the way toward tuberculosis elimination, we discuss M. tuberculosis transmission dynamics and point to areas for control interventions. Cases with 100% identical genotypes (RFLP patterns) were defined as clustered, and a cluster was defined as cases with an identical genotype. Of 4,601 included cases, corresponding to 76% of reported and 97% of culture-verified tuberculosis cases in the country, 56% were clustered, of which 69% were Danes. Generally, Danes were more often in large clusters (= 50 persons), older (mean age, 45 years), and male (male/female ratio, 2.5). Also, Danes had a higher cluster frequency within a 2-year observation window (60.8%), and higher clustering rate of new patterns over time, compared to immigrants. A dominant genotype, cluster 2, constituted 44% of all clustered and 35% of all genotyped cases. This cluster was primarily found among Danish males, 30 to 59 years of age, often socially marginalized, and with records of alcohol abuse. In Danes, cluster 2 alone was responsible for the high cluster frequency level. Immigrants had a higher incidence of clustered tuberculosis at a younger age (0 to 39 years). To achieve tuberculosis elimination in Denmark, high-risk transmission environments, like the cluster 2 environment in Danes, and specific transmission chains in immigrants in the capital area, e.g., homeless/socially marginalized Somalis/Greenlanders, often with alcohol abuse, must be targeted, including groups with a high risk of reactivation.
SETTING: Denmark, a high-income country with a low prevalence of tuberculosis. OBJECTIVE AND DESIGN: Molecular epidemiological studies of Mycobacterium tuberculosis strains are conducted worldwide, and distinct strains have been associated with large outbreaks of tuberculosis. This is the first systematic population-based search for distinct strains of M. tuberculosis in Denmark among 4102 strains DNA fingerprinted nationwide from 1992 to 2001. RESULTS: A specific strain of M. tuberculosis has emerged rapidly in Denmark: in 1992, the Danish Cluster 2 strain accounted for 5.8% of all culture-positive Danish-born cases, increasing to 29.0% in 2001. The Cluster 2 cases were on average younger (41.8 vs. 51.4 years), more likely to be male (81.4% vs. 64.1%), and more likely to have pulmonary involvement only (90.3% vs. 64.6%) than other Danish-born cases. During the first 4 observation years, they were mainly found in the capital city, Copenhagen, but were later increasingly observed in the provinces. CONCLUSION: The reasons for the increasing dominance and change in geographical distribution of Cluster 2 strains in Denmark is unknown, but may be partly explained by the fact that Cluster 2 is associated with younger males with pulmonary disease manifestation. We consider it as an outbreak and believe the situation requires increased focus on early tuberculosis diagnosis and control of transmission in Denmark.
The BCG vaccine's ability to prevent Mycobacterium tuberculosis infection (MTI) remains highly debated. In Greenland, BCG vaccination was introduced in 1955, but was temporarily discontinued (1991-1996) due to nationwide policy changes. The study aimed to use the transient stop in BCG vaccination to evaluate the effect of vaccination on MTI prevalence and TB incidence.
MTI study: A cross-sectional study (2012), comprising East Greenlanders born during 1982-2006, evaluated the effect of BCG vaccination on MTI prevalence; a positive interferon ? release assay defined an MTI case. Associations were estimated using logistic regression. TB study: a cohort study covering the same birth cohorts with follow-up until 2012 evaluated the vaccine's effect on TB incidence. A personal identifier allowed for follow-up in the TB notification system. Associations were estimated using Cox regression.
MTI study: Included 953 participants; 81% were BCG-vaccinated; 29% had MTI, 23% among vaccinated and 57% among non-vaccinated. BCG vaccination reduced the odds of MTI, OR 0.52 (95% CI 0.32 to 0.85), p=0.01. Vaccine effectiveness against MTI was 20%. TB study: Included 1697 participants followed for 21,148 person-years. 6% were notified with TB, 4% among vaccinated and 11% among non-vaccinated. BCG vaccination reduced the risk of TB, HR 0.50 (95% CI 0.26 to 0.95), p=0.03, yielding a vaccine effectiveness of 50%.
BCG vaccination was effective in reducing both MTI and TB disease among children and young adults in a TB high-endemic setting in Greenland.
Two groups of Danish prisoners on remand (in solitary confinement and not in solitary confinement) were examined by interview on reception (n = 133 & n = 95) in order to evaluate the prevalence and form of administration of opioid abuse/dependence. About 50% had abused opioids during their lifetime; one third were dependent at the time of reception. Twenty percent of opioid dependent prisoners administered opioids by smoking. More intravenous users were treated with methadone before and during imprisonment than those who were dependent on smoking opioids. Few were objectively suffering from withdrawal symptoms. The psycho-social impact of dependence on smoking heroin and intravenous heroin one month prior to imprisonment was at the same level and substantial as measured by the Global Assessment Scale.
OBJECTIVE: To compare two levels of stress (solitary confinement (SC) and non-SC) among remand prisoners as to incidence of psychiatric disorders in relation to prevalent disorders. METHOD: Longitudinal repeated assessments were carried out from the start and during the remand phase of imprisonment. Both interview-based and self-reported measures were applied to 133 remand prisoners in SC and 95 remand prisoners in non-SC randomly selected in a parallel study design. RESULTS: Incidence of psychiatric disorders developed in the prison was significantly higher in SC prisoners (28%) than in non-SC prisoners (15%). Most disorders were adjustment disorders, with depressive disorders coming next. Incident psychotic disorders were rare. The difference regarding incidence was primarily explained by level of stress (i.e. prison form) rather than confounding factors. Quantitative measures of psychopathology (Hamilton Scales and General Health Questionnaire) were significantly higher in subjects with prevalent and incident disorders compared to non-disordered subjects. CONCLUSION: Different levels of stress give rise to different incidence of psychiatric morbidity among remand prisoners. The surplus of incident disorders among SC prisoners is related to SC, which may act as a mental health hazard.
Transmission of Mycobacterium tuberculosis continues at high rates among Greenland-born persons in Greenland and Denmark, with 203 and 450 notified cases per 10(5) population, respectively, in the year 2010. Here, we document that the predominant M. tuberculosis outbreak strain C2/1112-15 of Danish origin has been transmitted to Greenland-born persons in Denmark and subsequently to Greenland, where it is spreading at worrying rates and adding to the already heavy tuberculosis burden in this population group. It is now clear that the C2/1112-15 strain is able to gain new territories using a new population group as the "vehicle." Thus, it might have the ability to spread even further, considering the potential clinical consequences of strain diversity such as that seen in the widely spread Beijing genotype. The introduction of the predominant M. tuberculosis outbreak strain C2/1112-15 into the Arctic circumpolar region is a worrying tendency which deserves attention. We need to monitor whether this strain already has, or will, spread to other countries.
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