Karen Bjorn-Mortensen

Tracing Mycobacterium tuberculosis transmission by whole genome sequencing in a high incidence setting: a retrospective population-based study in East Greenland

In East Greenland, a dramatic increase of tuberculosis (TB) incidence has been observed in recent years. Classical genotyping suggests a genetically similar Mycobacterium tuberculosis (Mtb) strain population as cause, however, precise transmission patterns are unclear. We performed whole genome sequencing (WGS) of Mtb isolates from 98% of culture-positive TB cases through 21 years (n = 182) which revealed four genomic clusters of the Euro-American lineage (mainly sub-lineage 4.8 (n = 134)). The time to the most recent common ancestor of lineage 4.8 strains was found to be 100 years. This sub-lineage further diversified in the 1970s, and massively expanded in the 1990s, a period of lowered TB awareness in Greenland. Despite the low genetic strain diversity, WGS data revealed several recent short-term transmission events in line with the increasing incidence in the region. Thus, the isolated setting and the uniformity of circulating Mtb strains indicated that the majority of East Greenlandic TB cases originated from one or few strains introduced within the last century. Thereby, the study shows the consequences of even short interruptions in TB control efforts in previously TB high incidence areas and demonstrates the potential role of WGS in detecting ongoing micro epidemics, thus guiding public health efforts in the future.

The origin and emergence of an HIV-1 epidemic: from introduction to endemicity.

Objectives:To describe, at patient-level detail, the determining events and factors involved in the development of a countrys HIV-1 epidemic. Design:Clinical information for all recorded Greenlandic HIV-1 patients was analysed and correlated with both novel and previously analysed pol sequences, representing more than half of the entire Greenlandic HIV-1 epidemic. Archival blood samples were sequenced to link early infection chain descriptions to the subsequent epidemic. Methods:In-depth phylogenetic analyses were used in synergy with clinical information to assess number of introductions of HIV-1 into Greenland, the source of geographic origin, time of epidemic introduction and its epidemiological characteristics such as initial transmission chain, geographic dispersal within Greenland, method of infection, cluster size, sociological and behavioural factors. Results:Despite its small population size and isolated geographic location, data support at least 25 introductions of HIV-1 into Greenland. Only a single of these led to an epidemic. This introduction occurred between 1985 and 1986, and the epidemic cluster is still active. Facilitating factors for the emergence and spread of the epidemic cluster include a rapid transition from MSM to heterosexual spread, high prevalence of other sexually transmitted diseases, rapid dispersal to larger cities and early emergence in a distinct subpopulation with high-risk behaviour including disregard for condomizing. Conclusions:The synergistic use of disparate data categories yields such unique detail, that the Greenland epidemic now serves as a model example for the epidemic emergence of HIV-1 in a society. This renders it suitable for testing of present and future sequence-based epidemiological methodologies.

The HIV epidemic in Greenland – a slow spreading infection among adult heterosexual Greenlanders

Introduction . We aimed to characterise the HIV epidemic in Greenland and to determine incidence, prevalence, mortality rates (MR) and specific causes of deaths. Study design . The study design used was population-based nationwide cohort study. Methods . We included all patients diagnosed with HIV in Greenland before 2011. Data were obtained from patient files, death certificates and the mandatory reports of HIV cases. Incidence and prevalence were estimated as cases/100,000 adults/year and MR as deaths/1,000 person-years (PYR). MRs were estimated for the pre-HAART (≤1996), early-HAART (1997–2004) and late-HAART (≥2005) periods. Deaths were considered AIDS related, if CD4 count <6 months before death was <200 cells/µL and/or an AIDS-related event occurred <12 months of death. Results . We identified 171 cases of HIV among adult Greenlanders. Of these, 133 (78%) were infected in Greenland, 17 (10%) in Denmark and 21 (12%) in other places. The majority was infected through heterosexual contact [127 (74%)], 30 (18%) through homosexual contact, 3 (2%) through intravenous drug use and 11 (6%) through other or unknown routes of transmission. The median age at HIV diagnosis was 46 years (interquartile range 34–56). The incidence increased from 3.8 before 1989 to 29.7 cases/100,000 adults/year in the late 1990s. The incidence has slowly declined to approximately eight cases/100,000 adults/year. Prevalence increased to a maximum in 2009 (174.9/100,000 inhabitants), and slowly declined since then. A total of 79 have died and 25 have emigrated. MRs were high in the pre- and early-HAART periods, 65.3 [95% confidence intervals (CI) 40.0–106.6] and 87.0 [95% CI 63.5–119.0], and a large fraction of deaths were AIDS related. In the late-HAART period, MR has declined markedly to 53.4 (95% CI 35.8–79.7) with a substantial decline in AIDS-related MR. Conclusion . Heterosexual contact is the main route of HIV infection and the patients are diagnosed at a median age of 46. The incidence of newly diagnosed HIV patients has decreased markedly since year 2000. Mortality is high although declining in recent years. To access the supplementary material to this article please see Supplementary files under Article Tools online

Direct DNA Extraction from Mycobacterium tuberculosis Frozen Stocks as a Reculture-Independent Approach to Whole-Genome Sequencing

ABSTRACT Culturing before DNA extraction represents a major time-consuming step in whole-genome sequencing of slow-growing bacteria, such as Mycobacterium tuberculosis. We report a workflow to extract DNA from frozen isolates without reculturing. Prepared libraries and sequence data were comparable with results from recultured aliquots of the same stocks.

Non-specific effects of BCG vaccination on morbidity among children in Greenland: a population-based cohort study

Background The potential non-specific effects of BCG (Bacillus Calmette-Guérin) vaccination, with reported reduction of infectious disease morbidity among vaccinated children, in addition to the protective effect against tuberculosis (TB), are highly debated. In Greenland, BCG vaccination was introduced in 1955, but temporarily discontinued from 1991 to 1996 due to nationwide policy changes. Using the transient vaccination stop, we aimed to investigate possible non-specific effects of BCG vaccination by measuring nation-wide hospitalization rates due to infectious diseases other than TB among vaccinated and unvaccinated children. Methods A retrospective cohort study including all children born in Greenland aged 3 months to 3 years from 1989 to 2004. A personal identification number assigned at birth allowed for follow-up through national registers. Information on hospitalization due to infectious diseases was obtained from the Greenlandic inpatient register using ICD-8 and ICD-10 codes. Participants with notified TB were censored. Incidence rate ratios (IRR) were estimated using Poisson regression. Results Overall, 19 363 children, hereof 66% BCG-vaccinated, were followed for 44 065 person-years and had 2069 hospitalizations due to infectious diseases. IRRs of hospitalization in BCG-vaccinated as compared with BCG-unvaccinated children were 1.07 [95% confidence interval (CI) 0.96-1.20] for infectious diseases overall, and specifically 1.10 (95% CI 0.98-1.24) for respiratory tract infections. Among BCG-vaccinated children aged 3 to 11 months, the IRR of hospitalization due to infectious diseases was 1.00 (95% CI 0.84-1.19) as compared with BCG-unvaccinated children. Conclusion Our results do not support the hypothesis that neonatal BCG vaccination reduces morbidity in children caused by infectious diseases other than TB.

Incidence of Greenlandic stroke-survivors in Greenland: A 2-year cross-sectional study

Objectives To estimate age- and gender-specific incidence rates among Greenlandic stroke-survivors. Study design The study was performed as a cross-sectional observational study. Methods All Greenlandic patients admitted to Queen Ingrids Hospital (QIH) with stroke in 2011 and 2012 were included in the study. Data were obtained from patient files and the Central Civil Registration System. Age- and gender-specific incidence rates were estimated as cases/100,000 adults/year. Direct age-standardized incidence rate was calculated using the WHO 2000–2005 population as the standard. Results In 2011 and 2012, 156 cases of stroke were registered, 72 (46.2%) males and 84 (53.8%) females. The overall incidence rate of stroke was 155/100,000 person-years (95% CI 121–190), with ischemic stroke accounting for 89.1% of these. No significant differences were seen between men and women. Direct age-standardized incidence rate was 149/year/100,000 (95% CI 192–264). Median age at time of diagnosis was 60 years (interquartile range 53–69). Conclusions This study reports an age-standardized all-stroke incidence rate of Greenlandic stroke-survivors in Greenland within the wide range as incidences in Western Europe. A noticeable difference when compared to Denmark was that male and female incidence were approximately the same, and that incidence rates were high in the younger age groups. The majority of strokes were of ischemic origin.

Tuberculosis outbreak in East Greenland: groups at risk in an isolated arctic setting

In 2009, an unusually high number of tuberculosis (TB) cases were reported from a settlement (Settlement X) in East Greenland. 4 years earlier, screening among schoolchildren had documented all children in this settlement to be free of Mycobacterium tuberculosis infection (MTI), whereas similar screenings had shown an MTI prevalence of 8% among schoolchildren in the rest of East Greenland [1]. The average TB incidence rate in East Greenland 5 years prior to the outbreak was ∼300 per 100 000 populations (fig. 1) [2, 3]. Teenagers from a previously M. tuberculosis transmission-free settlement were at particular risk during a TB outbreak http://ow.ly/KALqZ

Rapid change in the ciprofloxacin resistance pattern among Neisseria gonorrhoeae strains in Nuuk, Greenland: time to reconsider preventive and treatment strategies.

Objectives Sexually transmitted infections (STIs), including infections with Neisseria gonorrhoeae (GC), are highly incident in Greenland. Since January 2011, GC testing has been performed on urine with nucleic acid amplification tests (NAATs) by strand displacement amplification (Becton Dickinson ProbeTec). Monitoring of GC antibiotic susceptibility by culture was introduced in Nuuk in 2012. Until 2014, no cases of ciprofloxacin-resistant GC strains were reported. In this paper, we report the finding of ciprofloxacin-resistant GC and describe the most recent incidence of GC infections in Greenland. Methods The number of urine NAATs and culture-positive swabs from January to October 2014 were obtained from the Central Laboratory at Queens Ingrids Hospital in Nuuk and stratified on gender, place and period of testing. Incidence rates were estimated as number of urine NAAT * (12/10) per 100,000 inhabitants. Men in Nuuk with a positive NAAT for GC were encouraged to provide a urethral swab for culture and susceptibility testing. Results From January to October 2014, a total of 5,436 urine GC NAATs were performed on patients from Nuuk and 9,031 from the rest of Greenland. Of these, 422 (8%) and 820 (9%) were positive, respectively. From January to August, 6 (15%) cultures from Nuuk were ciprofloxacin resistant while in September and October, 26 (59%) were ciprofloxacin resistant (p<0.01). In total, 35 (40%) of 88 culture-positive isolates showed ciprofloxacin resistance. GC incidence in Nuuk was 3,017 per 100,000 inhabitants per year, compared to 2,491 per 100,000 inhabitants per year in the rest of Greenland. Conclusion Within a short period, a rapid and dramatic change in ciprofloxacin susceptibility among GC strains isolated in Nuuk was documented and recommendation for first line treatments has changed. Continued monitoring and rethinking of primary and secondary preventive initiatives is highly recommended in this high GC incidence setting.

High prevalence of atrial fibrillation among Greenlanders with ischemic stroke - atrial fibrillation found in more than 30% of cases

Objectives To estimate the prevalence of atrial fibrillation among Greenlanders with ischemic stroke. Study design A cross-sectional study. Methods Information on atrial fibrillation and vitamin K antagonistic treatment at admittance and at discharge was obtained for Greenlanders admitted to Queen Ingrids Hospital in Nuuk with an ischemic stroke in 2011 or in 2012 with methods described in details elsewhere. Results Of 139 patients (64 males and 75 females) Greenlanders with an ischemic stroke in 2011 (n=74) or 2012 (n=65), 5.0% (n=7) had known atrial fibrillation prior to stroke compared to 32.4% (n=45) after discharge (p<0.01). Conclusions More than 30% of ischemic stroke patients in this study had atrial fibrillation and only 5% were diagnosed prior to the stroke, suggesting that unknown atrial fibrillation is a substantial risk factor of ischemic stroke among Greenlanders.

Erythema nodosum and the risk of tuberculosis in a high incidence setting

Objective This study estimates the erythema nodosum (EN) incidence in a tuberculosis (TB) endemic setting and evaluates the likelihood of a subsequent TB diagnosis among individuals with Mycobacterium tuberculosis infection (MTI) with or without EN. Design We estimated EN incidence rates (IRs) in East Greenland in 2010–2011 and conducted a cohort study following all individuals who tested positive for MTI from 1 January 2010 until 31 December 2012. A personal identifier allowed individual follow-up in the mandatory TB register. MTI was defined by a positive interferon-gamma release assay. TB incidence rate ratios (IRRs) among participants with or without EN were estimated with the Cox proportional hazard model. Results We identified 38 EN cases corresponding to an IR of 500/100,000 inhabitants/year. All cases were among individuals with MTI. The EN IR was 11.79 (95% CI 5.73–24.27) times higher for BCG-unvaccinated compared with BCG-vaccinated individuals. The TB IRR was 25 (95% CI 11–60) within 1 month of EN compared to individuals without EN. Conclusion This study documents a high EN incidence in a TB endemic region. EN occurred only in individuals with MTI, and predominantly among BCG-unvaccinated individuals. EN was significantly associated with a TB diagnosis within 1 month of diagnosis.Objective This study estimates the erythema nodosum (EN) incidence in a tuberculosis (TB) endemic setting and evaluates the likelihood of a subsequent TB diagnosis among individuals with Mycobacterium tuberculosis infection (MTI) with or without EN. Design We estimated EN incidence rates (IRs) in East Greenland in 2010-2011 and conducted a cohort study following all individuals who tested positive for MTI from 1 January 2010 until 31 December 2012. A personal identifier allowed individual follow-up in the mandatory TB register. MTI was defined by a positive interferon-gamma release assay. TB incidence rate ratios (IRRs) among participants with or without EN were estimated with the Cox proportional hazard model. Results We identified 38 EN cases corresponding to an IR of 500/100,000 inhabitants/year. All cases were among individuals with MTI. The EN IR was 11.79 (95% CI 5.73-24.27) times higher for BCG-unvaccinated compared with BCG-vaccinated individuals. The TB IRR was 25 (95% CI 11-60) within 1 month of EN compared to individuals without EN. Conclusion This study documents a high EN incidence in a TB endemic region. EN occurred only in individuals with MTI, and predominantly among BCG-unvaccinated individuals. EN was significantly associated with a TB diagnosis within 1 month of diagnosis.Objective This study estimates the erythema nodosum (EN) incidence in a tuberculosis (TB) endemic setting and evaluates the likelihood of a subsequent TB diagnosis among individuals with Mycobacterium tuberculosis infection (MTI) with or without EN. Design We estimated EN incidence rates (IRs) in East Greenland in 2010-2011 and conducted a cohort study following all individuals who tested positive for MTI from 1 January 2010 until 31 December 2012. A personal identifier allowed individual follow-up in the mandatory TB register. MTI was defined by a positive interferon-gamma release assay. TB incidence rate ratios (IRRs) among participants with or without EN were estimated with the Cox proportional hazard model. Results We identified 38 EN cases corresponding to an IR of 500/100,000 inhabitants/year. All cases were among individuals with MTI. The EN IR was 11.79 (95% CI 5.73-24.27) times higher for BCG-unvaccinated compared with BCG-vaccinated individuals. The TB IRR was 25 (95% CI 11-60) within 1 month of EN compared to individuals without EN. Conclusion This study documents a high EN incidence in a TB endemic region. EN occurred only in individuals with MTI, and predominantly among BCG-unvaccinated individuals. EN was significantly associated with a TB diagnosis within 1 month of diagnosis.