How pathogens affect the marine habitat use and migration of sea trout (Salmo trutta) in two Norwegian fjord systems.

Wild fish are confronting changing pathogen dynamics arising from anthropogenic disturbance and climate change. Pathogens can influence animal behaviour and life histories, yet there are little such data from fish in the high north where pathogen dynamics may differ from comparatively southern regions. We aimed to compare the pathogen communities of 160 wild anadromous brown trout in two fjords in northern Norway and to determine whether pathogens influenced area use or return to spawn. Application of high-throughput qPCR detected 11 of the 46 pathogens screened for; most frequently encountered were Ichthyobodo spp., Flavobacterium psychrophilum and Candidatus Branchiomonas cysticola. The rate of returning to freshwater during the spawning season was significantly lower for the Skjerstadfjord fish. Piscichlamydia salmonis and F. psychrophilum were indicator species for the Skjerstadfjord and pathogen communities in the two fjords differed according to perMANOVA. Individual length, Fulton's condition factor and the time between first and last detection of the fish were not related to the presence of pathogens ordinated using non-metric multidimensional scaling (NMDS). However, there was evidence that pathogen load was correlated with the expression of smoltification genes, which are upregulated by salmonids in freshwater. Correspondingly, percentage of time in freshwater after release was longer for fish with greater pathogen burdens.

Dietary Intake of Marine Polyunsaturated n-3 Fatty Acids and Risk of Recurrent Venous Thromboembolism.

BACKGROUND: Limited knowledge exists on the association between intake of long-chained n-3 polyunsaturated fatty acids (n-3 PUFAs) and risk of recurrence and all-cause mortality in patients with venous thromboembolism (VTE). OBJECTIVES: This article investigates whether intake of marine n-3 PUFAs was associated with risk of recurrence and mortality in patients with incident VTE. METHODS: A total of 595 patients with incident VTE and available data on n-3 PUFA intake were derived from the Tromsø Study surveys 4 (1994-1995) and 6 (2007-2008). Weekly intake of n-3 PUFAs was categorized as low, medium, and high based on tertiles. Recurrent VTEs and all-cause mortality were registered up to December 31, 2016. Hazard ratios (HRs) were calculated using Cox regression models with the low intake category as reference. RESULTS: There were 98 recurrent VTEs and 227 deaths during follow-up. Overall, we found no association between intake of n-3 PUFAs and risk of recurrent VTE. However, inverse associations were found for high intakes in patients with unprovoked VTE (HR 0.45, 95% confidence interval [CI]: 0.20-1.01), cancer-free patients (HR 0.51, 95% CI: 0.27-0.95), and deep vein thrombosis (DVT) patients (HR 0.49, 95% CI: 0.24-0.97). The inverse associations were more evident when follow-up was restricted to the time after discontinuation of anticoagulant therapy. No association was observed between intake of n-3 PUFAs and mortality after incident VTE. CONCLUSION: A high dietary intake of marine n-3 PUFAs was associated with lower risk of recurrent VTE after unprovoked index events, DVT, and in cancer-free patients.

Cardiorespiratory fitness and future risk of venous thromboembolism.

BACKGROUND: Cardiorespiratory fitness (CRF) is a strong predictor of future arterial cardiovascular disease and premature mortality. However, there are limited data on the association between CRF and the risk of incident venous thromboembolism (VTE). OBJECTIVES: To investigate whether estimated CRF (eCRF) was associated with the risk of incident VTE in a cohort recruited from the general population. METHODS: Participants (n = 10 393) from the sixth survey of the Tromsø Study (2007-08) were included, and incident VTEs were recorded up to 31 December 2016. CRF was estimated in sex-specific algorithms based on age, waist circumference, resting heart rate, and self-reported physical activity. Hazard ratios (HRs) with 95% confidence intervals (CIs) of VTE according to categories of eCRF were estimated in Cox regression models adjusted for sex with age as timescale. The impact of weight status was evaluated in analyses stratified by weight category. RESULTS: There were 176 incident VTEs during follow-up. Compared with individuals with eCRF < 85% of age-predicted, those with eCRF of 85% to 100% and >100% of age-predicted had 46% (HR 0.54; 95% CI 0.39-0.77) and 67% (HR 0.33; 95% CI 0.20-0.54) lower VTE risk, respectively. Compared with overweight/obese individuals with eCRF < 85% of age-predicted, overweight/obese individuals with eCRF ≥ 85% had 50% (HR 0.50, 95% CI 0.35-0.74) lower risk, and normal weight individuals with eCRF ≥ 85% had 55% (HR 0.45, 95% CI 0.30-0.68) lower risk. CONCLUSIONS: Higher eCRF was associated with lower risk of incident VTE. The association was independent of weight categories, suggesting that higher eCRF may modify the association between obesity and VTE.

Myocardial Infarction as a Transient Risk Factor for Incident Venous Thromboembolism: Results from a Population-Based Case-Crossover Study.

Patients with myocardial infarction (MI) are at increased short-term risk of venous thromboembolism (VTE). The mechanisms behind this association are unclear. We aimed to investigate the impact of acute MI as a transient risk factor for incident VTE while taking other concomitant VTE risk factors into account. We conducted a case-crossover study of VTE patients (n = 707) recruited from the fourth survey of the Tromsø Study. VTE risk factors and hospitalizations were registered during the 90-day period preceding the VTE diagnosis (hazard period) and in four 90-day control periods. Conditional logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for VTE according to acute MI and after adjustment for other risk factors. Additionally, we applied a mediation analysis to quantify how much the known transient risk factors account for the observed effect of MI on VTE risk. MI was recorded in 13 (1.8%) of the hazard periods and in 6 (0.2%) of the control periods, which yielded a crude OR of 11.9 (95% CI: 3.9-36.7). Adjustment for immobilization and infection yielded an OR of 2.7 (95% CI: 0.6-11.2). The OR was attenuated to 2.6 (95% CI: 0.6-11.9) after further adjustment for major surgery, trauma, red blood cell transfusion, and central venous catheterization. Approximately 60% of the association between MI and VTE was mediated through infection and immobilization. In conclusion, our findings suggest that the increased VTE risk after MI may to a large extent be explained by concomitant conditions related to MI, particularly infections and immobilization.

The Role of Stroke as a Trigger for Incident Venous Thromboembolism: Results from a Population-based Case-Crossover Study.

Stroke is associated with a short-term increased risk of subsequent venous thromboembolism (VTE). It is unclear to what extent this association is mediated by stroke-related complications that are potential triggers for VTE, such as immobilization and infection. We aimed to investigate the role of acute stroke as a trigger for incident VTE while taking other concomitant VTE triggers into account. We conducted a population-based case-crossover study with 707 VTE patients. Triggers were registered during the 90 days before a VTE event (hazard period) and in four preceding 90-day control periods. Conditional logistic regression was used to estimate odds ratios with 95% confidence intervals (CIs) for VTE according to triggers. Stroke was registered in 30 of the 707 (4.2%) hazard periods and in 6 of the 2,828 (0.2%) control periods, resulting in a high risk of VTE, with odds ratios of 20.0 (95% CI: 8.3-48.1). After adjustments for immobilization and infection, odds ratios for VTE conferred by stroke were attenuated to 6.0 (95% CI: 1.6-22.1), and further to 4.0 (95% CI: 1.1-14.2) when other triggers (major surgery, red blood cell transfusion, trauma, and central venous catheter) were added to the regression model. A mediation analysis revealed that 67.8% of the total effect of stroke on VTE risk could be mediated through immobilization and infection. Analyses restricted to ischemic stroke yielded similar results. In conclusion, acute stroke was a trigger for VTE, and the association between stroke and VTE risk appeared to be largely mediated by immobilization and infection.

Physical activity and risk of recurrence and mortality after incident venous thromboembolism.

BACKGROUND: Limited data exist on the relationship between physical activity and major complications after incident venous thromboembolism (VTE). OBJECTIVES: To investigate whether physical activity was associated with risk of recurrence and mortality in patients with VTE recruited from the general population. METHODS: Patients with incident VTE (n = 786) derived from the Tromsø Study surveys 4-6 (1994-1995, 2001-2002, and 2007-2008) were included, and data on physical activity were dichotomized according to the activity level reported in the survey preceding the incident VTE (inactive: <1 hour per week, active: ≥1 hour per week). Recurrent VTE and all-cause mortality were registered up to December 31, 2015. Hazard ratios (HRs) for recurrence and all-cause mortality were calculated using Cox regression models with the inactive group as reference. RESULTS: There were 139 recurrences and 395 deaths during follow-up. Physical activity was not associated with the risk of recurrence in men (HR model 2: 1.48, 95% confidence interval [CI] 0.83-2.65) or in women (HR model 2: 0.95, 95% CI 0.52-1.74). In contrast, physical activity was associated with a 28% lower risk of mortality during 10 years of follow up (HR model 3: 0.72, 95% CI 0.57-0.91). The inverse association was stronger in patients with a first deep vein thrombosis ( HR model 2: 0.59, 95% CI 0.44-0.79) than a pulmonary embolism (HR model 3: 0.87, 95% CI 0.61-1.26). CONCLUSION: Our results suggest that habitual physical activity prior to incident VTE does not influence the risk of recurrence. In contrast, active individuals were at lower risk of mortality, particularly following deep vein thrombosis.

Dietary intake of marine n-3 polyunsaturated fatty acids and future risk of venous thromboembolism.

BACKGROUND: Studies on the association between long-chained n-3 polyunsaturated fatty acids (n-3 PUFAs) and risk of venous thromboembolism (VTE) are conflicting, potentially due to challenges related to assessment of n-3 PUFA intake and changes in diet during follow-up. OBJECTIVES: To investigate whether dietary intake of marine n-3 PUFAs was associated with risk of incident VTE in a population-based cohort with repeated assessments of n-3 PUFA intake. METHODS: We recruited 21 970 participants (after excluding 7570 with incomplete data) from the fourth (1994-1995) and sixth (2007-2008) surveys of the Tromsø Study, and recorded incident VTEs up to 2016. Intake of n-3 PUFAs was computed from self-reported consumption of fat and lean fish, fish spread, and supplements. Cox proportional hazards regression models with n-3 PUFA intake as a time-varying variable were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for VTE across quartiles (Q) of n-3 PUFA intake. RESULTS: There were 541 incident VTEs during follow-up. Compared to Q1, subjects in Q2-4 had 22%-26% lower risk of VTE (HR Q2 0.74, 95% CI 0.57-0.96; HR Q3 0.77, 95% CI 0.59-0.99; HR Q4 0.78, 95% CI 0.61-1.00). The association was most pronounced for provoked VTE, particularly provoked pulmonary embolism (PE), with risk estimates of 0.42 (95% CI 0.25-0.72), 0.40 (95% CI 0.23-0.68), and 0.61 (95% CI 0.38-0.96) for Q2-4, respectively. CONCLUSIONS: Dietary intake of marine n-3 PUFAs was associated with a lower risk of VTE, particularly provoked PE. The association displayed a threshold pattern and suggested a protective effect of an n-3 PUFA intake ≥4.7 g/week.

Acute infection as a trigger for incident venous thromboembolism: Results from a population-based case-crossover study.

BACKGROUND: A bidirectional relation exists between acute infection and immobilization, and both are triggers for venous thromboembolism (VTE). To what extent the association between infection and VTE-risk is explained by immobilization is unknown. AIMS: To investigate the impact of hospitalization with acute infection on the VTE-risk in patients with and without concomitant immobilization, and to explore the differential impact of respiratory- (RTI) and urinary- (UTI) tract infections on the risk of deep vein thrombosis (DVT) and pulmonary embolism (PE). METHODS: We conducted a case-crossover study of VTE-patients (n = 707) recruited from a general population. Hospitalizations and VTE-triggers were registered during the 90 days before a VTE (hazard period) and in four preceding 90-day control periods. Conditional logistic regression was used to estimate odds ratios (ORs) for VTE according to triggers. RESULTS: Acute infection was registered in 267 (37.8%) of the hazard periods and in 107 (3.8%) of the control periods, corresponding to a high VTE-risk after infection (OR 24.2, 95% CI 17.2-34.0), that was attenuated to 15-fold increased after adjustment for immobilization. The risk was 20-fold increased after infection without concomitant immobilization, 73-fold increased after immobilization without infection, and 141-fold increased with the two combined. The risk of PE was apparently higher after RTIs (OR 48.3, 95% CI 19.4-120.0) than UTIs (OR 12.6, 95% CI 6.4-24.7), but diminished in sensitivity analyses excluding uncertain RTI diagnoses. CONCLUSIONS: Our findings suggest that hospitalization with infection is a strong VTE-trigger also in non-immobilized patients. Infection and immobilization had a synergistic effect on the VTE-risk.

C-reactive protein and risk of venous thromboembolism: results from a population-based case-crossover study.

Long-term, low-grade inflammation does not seem to be a risk factor for venous thromboembolism. The impact of acute inflammation, regardless of cause, on risk of venous thromboembolism is scarcely studied. We aimed to investigate the impact of acute inflammation, assessed by C-reactive protein, on short-term risk of venous thromboembolism. We conducted a case-crossover study of patients with venous thromboembolism (n=707) recruited from a general population. Information on triggers and C-reactive protein levels were retrieved from hospital records during the 90 days before the event (hazard period) and in four preceding 90-day control periods. Conditional logistic regression was used to obtain ß coefficients for change in natural log (ln) transformed C-reactive protein from control to hazard periods and to determine corresponding odds ratios for venous thromboembolism. Median C-reactive protein was 107 mg/L in the hazard period, and ranged from 7 mg/L to 16 mg/L in the control periods. The level of C-reactive protein was 58% (95% CI 39-77%) higher in the hazard period than in the control periods. A one-unit increase in ln-C-reactive protein was associated with increased risk of venous thromboembolism (OR 1.79, 95% CI 1.48-2.16). The risk estimates were only slightly attenuated after adjustment for immobilization and infection. In stratified analyses, ln-C-reactive protein was associated with increased risk of venous thromboembolism in cases with (OR 1.55, 95% CI 1.01-2.38) and without infection (OR 1.77, 95% CI 1.22-2.57). In conclusion, we found that acute inflammation, assessed by C-reactive protein, was a trigger for venous thromboembolism.

Temporal changes in benthic macrofauna on the west coast of Norway resulting from human activities.

Quantitative analyses of soft bottom invertebrate fauna from four Norwegian sill fjords show increased macrofaunal abundance, species richness, and a considerably changed benthic deep water macrofaunal composition in the inner parts of the fjord system. In retrospect, the analyses show significantly altered benthic macrofaunal community structure that was not reflected by the changes in the Shannon-Wiener diversity indices during regular monitoring. The observed changes are mainly due to an increased abundance of opportunistic species, especially of the polychaete Polydora sp. during the last 10-15 years which is correlated significantly to declining dissolved oxygen, rising temperature in the bottom water and increasing total organic matter in the sediment. Possible anthropogenic and climatic impact factors related to the observed macrofaunal changes and environmental consequences of the changes are discussed.

Time trends in incidence rates of venous thromboembolism in a large cohort recruited from the general population.

Changes in the incidence of venous thromboembolism (VTE) during the last two decades have not been extensively studied. Therefore, we studied time trends in the incidence rates (IRs) of deep vein thrombosis (DVT) and pulmonary embolism (PE) in a cohort of 26,855 subjects, aged 25-97 years, enrolled in the Tromsø study in 1994/1995. The subject were followed-up throughout 2012, and all symptomatic, objectively confirmed, incident VTEs were identified using multiple sources (hospital discharge-, radiology procedure- and autopsy registry) and validated by review of medical records. Age-adjusted biennial IR per 100,000 person years (PY) with 95% confidence intervals (CI) were calculated using Poisson regression. Between January 1996 and December 2012, 693 VTEs occurred during 368,150 PY of follow up. The IR of VTE increased from 158 (95% CI 116-199) in 1996/1997 to 201 (95% CI 160-243) in 2010/2011. There was a marked increase in the rates of PE (with/without concurrent DVT) ranging from 45 (95% CI 23-67) in 1996/1997 to 113 (95% CI 82-144) in 2010/2011, whereas the rates of isolated DVT decreased (112, 95% CI 77-146 in 1996/1997 and 88, 95% CI 61-115 in 2010/2011). Despite advances in prophylaxis, the IR of VTE has increased slightly during the last 15 years, mainly due to an increase in PE. Although the introduction of better diagnostic tools to some extent may explain the increase in PE rates, our findings suggest that there is still a need for improvement in risk factor management and prevention strategies of first time VTE.

A Retrospective Comparison of Ultrasound-Assisted Catheter-Directed Thrombolysis and Catheter-Directed Thrombolysis Alone for Treatment of Proximal Deep Vein Thrombosis.

BACKGROUND: Recent studies have suggested that catheter-directed thrombolysis (CDT) reduces development of post-thrombotic syndrome (PTS). Ultrasound-assisted CDT (USCDT) might enhance the efficiency of thrombolysis. We aimed to compare USCDT with CDT on efficacy, safety, development of PTS, and quality of life after long-term follow-up. METHODS: We describe a retrospective case series of 94 consecutive patients admitted with iliofemoral or more proximal deep vein thrombosis (DVT) to the University Hospital from 2002 to 2011, treated either with CDT or USCDT. Scheduled follow-up visits took place between April 2013 and January 2014. Venography measured the degree of residual luminal obstruction of the affected veins. Each patient completed the Short Form 36-item health survey assessment and the Venous Insufficiency Epidemiological and Economic Study-Quality of Life/Symptoms questionnaires. PTS was assessed using the Villalta scale. RESULTS: Risk factors of DVT were equally distributed between groups. In the USCDT group, we observed a significant decline in the duration of thrombolytic treatment (<48 h: 27 vs. 10 %), shortened hospital stay (median 6.0 days (IQR 5.0-9.0) vs. 8.0 (IQR 5.8-12.0)), and less implantation of (intravenous) stents (30 vs. 55 %). There was no difference in patency (76 vs. 79 % fully patent), prevalence of PTS (52 vs. 55 %), or quality of life between groups after long-term follow-up (median 65 months, range: 15-141). CONCLUSIONS: In this observational study, USCDT was associated with shortened treatment duration, shorter hospital stay, and less intravenous stenting, compared to CDT alone without affecting the long-term prevalence of PTS or quality of life.

Molecular tools for the detection and identification of Ichthyobodo spp. (Kinetoplastida), important fish parasites.

Ichthyobodo spp. are ectoparasitic flagellates of fish that may cause disease (ichthyobodosis), a common problem affecting the aquaculture industry worldwide. Ichthyobodosis in farmed fish is often associated with a range of other infectious agents and diagnosis in for example gill disease may be difficult. Sensitive and effective methods for detection and identification of Ichthyobodo spp. are needed to aid diagnosis of ichthyobodosis and epizootiological studies on Ichthyobodo spp. We have designed a specific quantitative real-time PCR assay targeting SSU rDNA for the detection of Ichthyobodo spp. infections. Also, several novel primer sets are presented for use in identification of Ichthyobodo spp. through PCR and sequencing. These PCR methods have been optimized and tested on samples from wild caught and farmed fish from different geographical areas in Norway. The real-time PCR assay has been tested for sensitivity and efficiency, and we present data demonstrating its use for absolute quantification of Ichthyobodo salmonis in tissue samples through RT-qPCR and qPCR. We demonstrate the use of the described set of molecular tools for the detection and sequencing of Ichthyobodo spp. from farmed and wild fish, and also show that they may aid the discovery of new Ichthyobodo species. The detection of light Ichthyobodo spp. infections through microscopy is time consuming and less sensitive compared to PCR methods. Initial real-time PCR testing and subsequent sequencing of positive samples is a powerful method that will increase diagnostic precision, aid carrier detection and promote species discoveries in the Ichthyobodonidae. Our preliminary observations indicate a high Ichthyobodo spp. diversity.

Ichthyobodo salmonis sp. n. (Ichthyobodonidae, Kinetoplastida), an euryhaline ectoparasite infecting Atlantic salmon (Salmo salar L.).

Phylogenetic analyses of SSU rDNA sequences have previously revealed the existence of 2 Ichthyobodo species able to infect Atlantic salmon (Salmo salar L.). Ichthyobodo necator sensu stricto (s.s.) is assumed to be a freshwater parasite, while a genetically distinct but undescribed species, Ichthyobodo sp. II sensu Todal et al. (2004) have been detected on Atlantic salmon in both fresh- and seawater. In the present study a morphological description of Ichthyobodo sp. II from the gills of salmon reared in fresh-, brackish- and seawater is presented, using both light- and electron microscopy. Comparative morphometry show that Ichthyobodo sp. II from both freshwater and seawater displays a different cell shape, and is significantly smaller than I. necator s.s. Also, ultrastructural characteristics distinguish these two species, notably differences in the attachment region and the presence of spine-like surface projections in Ichthyobodo sp. II. Based on both unique SSU rDNA sequences and morphological characteristics, we conclude that Ichthyobodo sp. II. represents a novel species for which we propose the name Ichthyobodo salmonis sp. n.

Ichthyobodo hippoglossi n. sp. (Kinetoplastea: Prokinetoplastida: Ichthyobodonidae fam. nov.), an ectoparasitic flagellate infecting farmed Atlantic halibut Hippoglossus hippoglossus.

Diseased Atlantic halibut Hippoglossus hippoglossus juveniles from a hatchery in western Norway showed gill and skin infections with an Ichthyobodo species. Genus Ichthyobodo contains a single valid species, I. necator, a parasite originally described from the skin and fins of a salmonid fish in freshwater. Many studies have identified this species from other hosts, but recent molecular evidence suggests that many Ichthyobodo spp. occur in both fresh- and seawater. We redescribe I. necator from Atlantic salmon Salmo salar skin infections in Norway and compare the morphology of I. necator with the form from halibut. A scheme to standardise the measurements of Ichthyobodo cells is presented. Morphologically, the Ichthyobodo species from the skin and gills of halibut differs from I. necator from salmon skin by shape (in air dried stained smears), by a low number of variably sized kinetoplasts and by a long flagellar pocket. There is also a clear increase in the number of kinetoplasts in L necator with increasing cell size (area), a pattern absent from Ichthyobodo sp. from halibut. The 2 forms are also clearly separated by their small subunit (ssu) rDNA sequences; alignments of partial ssu sequences showed 93.5 % similarity. Consequently, Ichthyobodo sp. from halibut is considered a new species, and is named I. hippoglossi n. sp. Its closest relative is Ichthyobodo sp. IV from another marine fish, the Atlantic cod Gadus morhua. A family, Ichthyobodonidae fam. nov. in the order Prokinetoplastida Vickerman, 2004, is erected to encompass Ichthyobodo spp.

Ichthyobodo necator (Kinetoplastida)--a complex of sibling species.

Ichthyobodo necator is a parasitic flagellate that attacks fishes, causing disease problems in freshwater worldwide. Findings of similar flagellates in strictly marine fishes have indicated that ichthyobodiosis may be caused by more than 1 flagellate species. We obtained partial small subunit rDNA (ssu rDNA) sequences of 14 Ichthyobodo isolates originating from fishes in Norway, Japan, Singapore, South Africa and Brazil, and identified 8 strains or species, including 2 species infecting cultured salmon in Norway. An Ichthyobodo species isolated from the skin of Atlantic salmon parr in freshwater is suggested to represent L. necator sensu stricto, while another species, showing particular affinity for the gills, infects salmon in both fresh- and seawater. Atlantic cod is infected with a marine Ichthyobodo species unrelated to those infecting salmonids; 2 cyprinids originating from different parts of the world had related Ichthyobodo strains/species, and 2 isolates from unrelated North and South American fishes were also closely related. The phylogenetic relationships of the Ichthyobodo isolates is described, and the implications of the molecular findings on past and future morphological studies of Ichthyobodo spp. are discussed.