Prevalence of latent tuberculosis infection in Syrian refugees to Canada

OBJECTIVES

Canada has accepted more than 25,000 Syrian refugees fearing persecution in their homeland. Canadian guidelines recommend screening recent refugees from high incidence countries for tuberculosis (TB) and latent TB infection (LTBI). The prevalence of TB in this population is unknown. A refugee clinic in Edmonton presented a unique opportunity to estimate prevalence of TB and LTBI in Syrian refugees arriving in Canada.

METHODS

In January 2016, 100 consecutive Syrian refugees were screened for TB with clinical assessment and LTBI using QuantiFERON Gold In-Tube assay (QFT-GIT). Patients with positive QFT-GIT were referred to Edmonton Tuberculosis Clinic (ETBC) for evaluation and, if appropriate, offered prophylaxis.

RESULTS

No cases of active TB were found. Valid QFT-GIT were measured in 99 of 100 individuals and of these, nine (9%) were positive using a threshold concentration of blood interferon-γ greater than 0.35 IU/L. Eight of the nine patients attended follow-up appointments; of these, seven began LTBI prophylaxis and all seven (78%) completed same.

CONCLUSION

The 9% (95% confidence interval 3-15%) prevalence of LTBI was higher than expected in this population.

Tuberculosis transmission in the Indigenous peoples of the Canadian prairies

SETTING

The prairie provinces of Canada.

OBJECTIVE

To characterize tuberculosis (TB) transmission among the Indigenous and non-Indigenous Canadian-born peoples of the prairie provinces of Canada.

DESIGN

A prospective epidemiologic study of consecutively diagnosed adult (age ≥ 14 years) Canadian-born culture-positive pulmonary TB cases on the prairies, hereafter termed "potential transmitters," and the transmission events generated by them. "Transmission events" included new positive tuberculin skin tests (TSTs), TST conversions, and secondary cases among contacts.

RESULTS

In the years 2007 and 2008, 222 potential transmitters were diagnosed on the prairies. Of these, the vast majority (198; 89.2%) were Indigenous peoples who resided in either an Indigenous community (135; 68.2%) or a major metropolitan area (44; 22.2%). Over the 4.5-year period between July 1st, 2006 and December 31st 2010, 1085 transmission events occurred in connection with these potential transmitters. Most of these transmission events were attributable to potential transmitters who identified as Indigenous (94.5%). With a few notable exceptions most transmitters and their infected contacts resided in the same community type. In multivariate models positive smear status and a higher number of close contacts were associated with increased transmission; adjusted odds ratios (ORs) and 95% confidence intervals (CIs), 4.30 [1.88, 9.84] and 2.88 [1.31, 6.34], respectively. Among infected contacts, being Indigenous was associated with disease progression; OR and 95% CI, 3.59 [1.27, 10.14] and 6.89 [2.04, 23.25] depending upon Indigenous group, while being an infected casual contact was less likely than being a close contact to be associated with disease progression, 0.66 [0.44, 1.00].

CONCLUSION

In the prairie provinces of Canada and among Canadian-born persons, Indigenous peoples account for the vast majority of cases with the potential to transmit as well as the vast majority of infected contacts. Active case finding and preventative therapy measures need to focus on high-incidence Indigenous communities.

“Finally when I started falling down”: Indigenous tuberculosis patient experiences of health and illness on the Canadian prairies

This paper adds evidence to a growing body of literature seeking to understand the disproportionate occurrence of tuberculosis (TB) in Indigenous populations of Canada and reveals insights that may inform effective interventions. As a disease, TB is recognized as a disorder of the body, for which there are successful treatments. Its persistence in some populations, however, requires an understanding of TB as an illness, whereby disease is shaped into behaviours and experiences. Fifty-five self-identified Indigenous participants with infectious pulmonary TB completed a questionnaire and an interview as part of the Determinants of Tuberculosis Transmission (DTT) project. Questionnaire data report on sociodemographic information and exposure to TB risk factors, while interview data describe participants’ experiences of TB within the context of their personal histories and everyday lives. Analysis showed that TB symptoms did not stand out as unusual in the everyday life and health experiences of participants. State of health and decisions about accessing healthcare were associated with socioeconomic deprivation, as well as negative experiences connected with historical and contemporary impacts of colonization. The “tipping point” concept effectively captures the shift in health that pushes participants to seek healthcare. Family, friends, and other caregivers are important influences and need to be part of the effort to avoid advanced TB illness and stop the cycle of transmission. More significantly, there is a need to address the structures and systems that produce and perpetuate life conditions that result in a usual state of compromised health.

Contact investigation outcomes of Canadian-born adults with tuberculosis in Indigenous and non-Indigenous populations in Alberta

OBJECTIVES

Contact investigations are a critical component of tuberculosis control in high-income countries. However, the relative success of conventional methods by population group and place of residence is unknown. This study compares outcomes of contact investigations of Canadian-born Indigenous tuberculosis cases living on- and off-reserve with other Canadian-born cases.

METHODS

In a retrospective analysis, Canadian-born adult culture-positive pulmonary TB cases (2001-2010) were identified. Characteristics of source cases and their contacts were compared by population group. Outcomes of contact investigations, including completion of recommended investigations and preventive therapy, were compared in multivariable analysis.

RESULTS

Of 171 cases of tuberculosis identified, 49 (29%) were Indigenous on-reserve, 62 (36%) Indigenous off-reserve, and 60 (35%) non-Indigenous or Canadian-born, "other". Indigenous people had more contacts identified per case compared to non-Indigenous patients. Case population group and smear status were the main predictors of the success of contact investigations. Of those recommended preventive therapy, close contacts of Indigenous cases on-reserve had the highest rate of completion, at 54%, vs. 41% and 37% for close contacts of Indigenous living off-reserve and Canadian-born "other" respectively (p = 0.02). Contacts of Indigenous cases living off-reserve had the greatest delay in assessment and the lowest rates of completion of assessment and preventive therapy. In multivariable analysis, population group, smear status of source case and proximity of contact were predictors of preventive therapy acceptance and/or completion.

CONCLUSIONS

Significant differences in outcomes of contact investigations were observed between population groups. The higher priority of contacts of smear-positive cases appears to influence efficiency of service delivery, regardless of population group. Jurisdictional differences in program delivery, resource availability and perceived risk of transmission likely influence outcomes of contact investigations.

Chest Radiographic Patterns and the Transmission of Tuberculosis: Implications for Automated Systems

BACKGROUND

Computer-aided detection to identify and diagnose pulmonary tuberculosis is being explored. While both cavitation on chest radiograph and smear-positivity on microscopy are independent risk factors for the infectiousness of pulmonary tuberculosis it is unknown which radiographic pattern, were it detectable, would provide the greatest public health benefit; i.e. reduced transmission. Herein we provide that evidence.

OBJECTIVES

1) to determine whether pulmonary tuberculosis in a high income, low incidence country is more likely to present with "typical" adult-type pulmonary tuberculosis radiographic features and 2) to determine whether those with "typical" radiographic features are more likely than those without such features to transmit the organism and/or cause secondary cases.

METHODS

Over a three-year period beginning January 1, 2006 consecutive adults with smear-positive pulmonary tuberculosis in the Province of Alberta, Canada, were identified and their pre-treatment radiographs scored by three independent readers as "typical" (having an upper lung zone predominant infiltrate, with or without cavitation but no discernable adenopathy) or "atypical" (all others). Each patient's pre-treatment bacillary burden was carefully documented and, during a 30-month transmission window, each patient's transmission events were recorded. Mycobacteriology, radiology and transmission were compared in those with "typical" versus "atypical" radiographs.

FINDINGS

A total of 97 smear-positive pulmonary tuberculosis cases were identified, 69 (71.1%) with and 28 (28.9%) without "typical" chest radiographs. "Typical" cases were more likely to have high bacillary burdens and cavitation (Odds Ratios and 95% Confidence Intervals: 2.75 [1.04-7.31] and 9.10 [2.51-32.94], respectively). Typical cases were also responsible for most transmission events-78% of tuberculin skin test conversions (p<0.002) and 95% of secondary cases in reported close contacts (p<0.01); 94% of secondary cases in "unreported" contacts (p<0.02).

CONCLUSION

As a group, smear-positive pulmonary tuberculosis patients with typical radiographic features constitute the greatest public health risk. This may have implications for automated detection systems.

A population-based study of tuberculosis case fatality in Canada: do Aboriginal peoples fare less well?

SETTING

The Province of Alberta, Canada.

OBJECTIVES

To explore trends in tuberculosis (TB) case fatality, compare TB case-fatality rates by population group and determine prognostic factors associated with TB-related death in Alberta from 1996 to 2012.

DESIGN

Retrospective cohort analysis.

RESULTS

During the study years, all-cause TB case fatality fell from 10.7% to 6.3%; the fall was attributable to a change in population structure, as there were more foreign-born and fewer older cases with time. A stable 2% of TB cases died without treatment. Compared to other population groups, Canadian-born Aboriginal case patients were more likely to die without treatment and to die younger. Of TB deaths that were TB-related, 68.9% occurred before or during the initial phase of treatment; of these, TB was a contributory cause of death in 77.5%, i.e., another medical condition was the primary cause of death. In multivariate analysis, age >64 years, aboriginality and miliary/disseminated or central nervous system disease were independent predictors for TB-related death.

CONCLUSION

Preventive therapy for those with latent tuberculous infection and a high-risk medical condition, early diagnosis of disease, and special support of older, Aboriginal or comorbid cases, once diagnosed, are necessary to further minimise TB case fatality in Alberta, Canada.

Y-STR genetic screening by high-resolution melting analysis

Currently, the widely used automated capillary electrophoresis-based short tandem repeat (STR) genotyping method for genetic screening in forensic practice is laborious, time-consuming, expensive, and technically challenging in some cases. Thus, new molecular-based strategies for conclusively identifying forensically relevant biological evidence are required. Here, we used high-resolution melting analysis (HRM) for Y-chromosome STR genotyping for forensic genetic screening. The reproducibility of the melting profile over dilution, sensitivity, discrimination power, and other factors was preliminarily studied in 10 Y-STR loci. The results showed that HRM-based approaches revealed more genotypes (compared to capillary electrophoresis), showed higher uniformity in replicate tests and diluted samples, and enabled successful detection of DNA at concentrations as low as 0.25 ng. For mixed samples, the melting curve profiles discriminated between mixed samples based on reference samples with high efficiency. The triplex Y-chromosome STR HRM assay was performed and provided a foundation for further studies such as a multiplex HRM assay. The HRM approach is a one-step application and the entire procedure can be completed within 2 h at a low cost. In conclusion, our findings demonstrate that the HRM-based Y-STR assay is a useful screening tool that can be used in forensic practice.

Do "Virtual" and "Outpatient" Public Health Tuberculosis Clinics Perform Equally Well? A Program-Wide Evaluation in Alberta, Canada

BACKGROUND

Meeting the challenge of tuberculosis (TB) elimination will require adopting new models of delivering patient-centered care customized to diverse settings and contexts. In areas of low incidence with cases spread out across jurisdictions and large geographic areas, a "virtual" model is attractive. However, whether "virtual" clinics and telemedicine deliver the same outcomes as face-to-face encounters in general and within the sphere of public health in particular, is unknown. This evidence is generated here by analyzing outcomes between the "virtual" and "outpatient" public health TB clinics in Alberta, a province of Western Canada with a large geographic area and relatively small population.

METHODS

In response to the challenge of delivering equitable TB services over long distances and to hard to reach communities, Alberta established three public health clinics for the delivery of its program: two outpatient serving major metropolitan areas, and one virtual serving mainly rural areas. The virtual clinic receives paper-based or electronic referrals and generates directives which are acted upon by local providers. Clinics are staffed by dedicated public health nurses and university-based TB physicians. Performance of the two types of clinics is compared between the years 2008 and 2012 using 16 case management and treatment outcome indicators and 12 contact management indicators.

FINDINGS

In the outpatient and virtual clinics, respectively, 691 and 150 cases and their contacts were managed. Individually and together both types of clinics met most performance targets. Compared to outpatient clinics, virtual clinic performance was comparable, superior and inferior in 22, 3, and 3 indicators, respectively.

CONCLUSIONS

Outpatient and virtual public health TB clinics perform equally well. In low incidence settings a combination of the two clinic types has the potential to address issues around equitable service delivery and declining expertise.

Making a timely diagnosis of pulmonary tuberculosis

Making a timely diagnosis of adult-type pulmonary tuberculosis (TB) is critical to interrupting transmission and optimizing treatment outcomes. A hypothesis based on clinical experience is that a timely diagnosis may be made by addressing seven clinical rubrics: six related to history, one to the laboratory. Responses may be considered to be part of a clinical heuristic for making a timely diagnosis of pulmonary TB. The larger the number of affirmative responses, the more likely the diagnosis, although it is probable some questions carry more weight than others. The radiograph is key and may almost be considered to be confirmatory of the history. Collectively, the responses should prompt suspicion of pulmonary TB - submission of sputum for acid-fast bacilli smear and culture, and respiratory isolation.

Therapeutic drug monitoring and the conservative management of chronic tuberculous empyema: case report and review of the literature

Background

Chronic tuberculous empyema (CTE) is a rare and unusual, low grade and protracted, infection of the pleural space resulting in marked thickening, even calcification of the visceral and parietal pleura. Historically its management has been extraordinarily challenging. Differential penetration of anti-TB drugs into the pleural space has resulted in acquired drug resistance and surgery to remove the empyema or close a complicating bronchopleural fistula (BPF) has been technically difficult or unacceptably hazardous. On the basis of limited experience, the combination of tube thoracostomy or catheter drainage and high-end dosing of anti-TB drugs has been recommended as an initial approach to these lesions. Herein we report the first well documented case of closure of a BPF and cure of a CTE using this approach. The chances of a favorable outcome are improved, we suggest, by using therapeutic drug monitoring (TDM) to guide high-end drug dosing.

Case Presentation

An 84 year old male immigrant to Canada from Croatia was diagnosed with a CTE after he developed a BPF. The diagnosis was made 62 years after what was, in retrospect, an episode of tuberculous pleurisy. He was treated with computed tomography-guided catheter drainage and TDM-guided high-end dosed anti-TB drugs (serum and pleural fluid drug concentrations) over a 10 month period. Sustained closure of the BPF and mycobacteriologic cure of the CTE was achieved. Drug concentrations in the present case and all other reported cases are summarized and interpreted.

Conclusion

When serum concentrations of the anti-TB drugs isoniazid, pyrazinamide and ethambutol at the high end of the normal range are achieved, pleural fluid concentrations at the low end of the normal range may be anticipated in CTE. Though highly protein bound drugs such as rifampin and moxifloxacin appear to penetrate CTEs less well, their free concentrations in the pleural space may be proportionately higher on account of lower protein concentrations. Interventional radiology and TDM increase the chances that conservative management of CTE will be successful.

Is early tuberculosis death associated with increased tuberculosis transmission?

INTRODUCTION

Tuberculosis (TB) is now a relatively uncommon disease in high income countries. As such, its diagnosis may be missed or delayed resulting in death before or shortly after the introduction of treatment. Whether early TB death is associated with increased TB transmission is unknown. To determine the transmission risk attributable to early TB death we undertook a case-control study.

METHODS

All adults who were: (1) diagnosed with culture-positive pulmonary TB in the Province of Alberta, Canada between 1996 and 2012, and (2) died a TB-related death before or within the first 60 days of treatment, were identified. For each of these "cases" two sets of "controls" were randomly selected from among culture-positive pulmonary TB cases that survived beyond 60 days of treatment. "Controls" were matched by age, sex, population group, +/- smear status. Secondary cases of "cases" and "controls" were identified using conventional and molecular epidemiologic tools and compared. In addition, new infections were identified and compared in contacts of "cases" that died before treatment and contacts of their smear-matched "controls". Conditional logistic regression was used to find associations in both univariate and multivariate analysis.

RESULTS

"Cases" were as, but not more, likely than "controls" to transmit. This was so whether transmission was measured in terms of the number of "cases" and smear-unmatched or -matched "controls" that had a secondary case, the number of secondary cases that they had or the number of new infections found in contacts of "cases" that died before treatment and their smear-matched "controls".

CONCLUSION

In a low TB incidence/low HIV prevalence country, pulmonary TB patients that die a TB-related death before or in the initial phase of treatment and pulmonary TB patients that survive beyond the initial phase of treatment are equally likely to transmit.

Feasibility and acceptability of web-based enhanced relapse prevention for bipolar disorder (ERPonline): trial protocol

BACKGROUND

Relapse prevention interventions for Bipolar Disorder are effective but implementation in routine clinical services is poor. Web-based approaches offer a way to offer easily accessible access to evidence based interventions at low cost, and have been shown to be effective for other mood disorders.

METHODS/DESIGN

This protocol describes the development and feasibility testing of the ERPonline web-based intervention using a single blind randomised controlled trial. Data will include the extent to which the site was used, detailed feedback from users about their experiences of the site, reported benefits and costs to mental health and wellbeing of users, and costs and savings to health services. We will gain an estimate of the likely effect size of ERPonline on a range of important outcomes including mood, functioning, quality of life and recovery. We will explore potential mechanisms of change, giving us a greater understanding of the underlying processes of change, and consequently how the site could be made more effective. We will be able to determine rates of recruitment and retention, and identify what factors could improve these rates.

DISCUSSION

The findings will be used to improve the site in accordance with user needs, and inform the design of a large scale evaluation of the clinical and cost effectiveness of ERPonline. They will further contribute to the growing evidence base for web-based interventions designed to support people with mental health problems.

Relative Versus Absolute Noncontagiousness of Respiratory Tuberculosis on Treatment

Objective:

To assess the validity of current estimates of the noncontagiousness of sputum smear-positive respiratory tuberculosis (TB) on treatment.

Design:

A descriptive analysis of the mycobacteriologic response to treatment.

Setting:

A TB inpatient unit of a Canadian hospital.

Patients:

Thirty-two HIV-seronegative patients with moderate to advanced sputum smear-positive respiratory TB were treated with uninterrupted, directly observed, weight-adjusted isoniazid, rifampin, and pyrazinamide. Each patient's initial isolate was drug susceptible and each patient's sputum mycobacteriology was systematically followed until 3 consecutive sputum smears were negative on 3 separate days.

Results:

The time to smear conversion varied remarkably (range, 8 to 115 days; average, 46 days) and was influenced by sputum sampling frequency. Only 3 patients (9.4%) had smear conversions by 14 days and only 8 (25%) had smear conversions by 21 days, the average time it took for drug susceptibility test results to become available. During the first 21 days of treatment, the semiquantitative sputum smear score decreased rapidly and the time to detection of positive cultures doubled. Within the time to smear conversion, virtually all smear-positive specimens (98%) were culture positive and only 34% of the patients had culture conversions (ie, 3 consecutive negative cultures).

Conclusion:

Current estimates of the noncontagiousness of sputum smear-positive respiratory TB on treatment (for 14 days, for 21 days, or until smear conversion) are estimates of relative noncontagiousness. They do not signal absolute noncontagiousness (culture conversion). Semiquantitative smear and time-to-detection data suggest that respiratory isolation beyond 21 days of optimal treatment should be selective.

Respirator-Fit Testing: Does It Ensure the Protection of Healthcare Workers Against Respirable Particles Carrying Pathogens?

Objective.

Respiratory protection programs, including fit testing of respirators, have been inconsistently implemented; evidence of their long-term efficacy is lacking. We undertook a study to determine the short- and long-term efficacy of training for fit testing of N95 respirators in both untrained and trained healthcare workers (HCWs).

Design.

Prospective observational cohort study.

Methods.

A group of at-risk, consenting HCWs not previously fit-tested for a respirator were provided with a standard fit-test protocol. Participants were evaluated after each of 3 phases, and 3 and 14 months afterward. A second group of previously fit-tested nurses was studied to assess the impact of regular respirator use on performance.

Results.

Of 43 untrained fit-tested HCWs followed for 14 months, 19 (44.2%) passed the initial fit test without having any specific instruction on respirator donning technique. After the initial test, subsequent instruction led to a pass for another 13 (30.2%) of the 43 HCWs, using their original respirators. The remainder required trying other types of respirators to acheive a proper fit. At 3 and 14 months' follow-up, failure rates of 53.5% (23 of 43 HCWs) and 34.9% (15 of 43 HCWs), respectively, were observed. Pass rates of 87.5%-100.0% were observed among regular users.

Conclusions.

Without any instruction, nearly 50% of the HCWs achieved an adequate facial seal with the most commonly used N95 respirator. Formal fit testing does not predict future adequacy of fit, unless frequent, routine use is made of the respirator. The utility of fit testing among infrequent users of N95 respirators is questionable.

Estimating surface NO2 and SO2 mixing ratios from fast-response total column observations and potential application to geostationary missions

Total-column nitrogen dioxide (NO₂) data collected by a ground-based sun-tracking spectrometer system (Pandora) and an photolytic-converter-based in-situ instrument collocated at NASA's Langley Research Center in Hampton, Virginia were analyzed to study the relationship between total-column and surface NO₂ measurements. The measurements span more than a year and cover all seasons. Surface mixing ratios are estimated via application of a planetary boundary-layer (PBL) height correction factor. This PBL correction factor effectively corrects for boundary-layer variability throughout the day, and accounts for up to ≈75 % of the variability between the NO₂ data sets. Previous studies have made monthly and seasonal comparisons of column/surface data, which has shown generally good agreement over these long average times. In the current analysis comparisons of column densities averaged over 90 s and 1 h are made. Applicability of this technique to sulfur dioxide (SO₂) is briefly explored. The SO₂ correlation is improved by excluding conditions where surface levels are considered background. The analysis is extended to data from the July 2011 DISCOVER-AQ mission over the greater Baltimore, MD area to examine the method's performance in more-polluted urban conditions where NO₂ concentrations are typically much higher.

Preventing tuberculosis in the foreign-born population of Canada: a mathematical modelling study

BACKGROUND

Foreign-born persons in Canada contribute 67% of all tuberculosis (TB) cases annually, but represent only 21% of the total population. Molecular epidemiological studies suggest that most foreign-born TB cases result from the reactivation of latent tuberculous infection (LTBI) acquired before immigration.

OBJECTIVE

To estimate the effect on incidence of a prevention strategy that would screen selected immigrants at arrival for LTBI and offer preventive treatment to those who test positive.

DESIGN

A deterministic model was developed to quantify the incidence of active TB in immigrants to Canada and validated with national immigration and TB case data.

RESULTS

Model simulations suggested that it would be optimal to screen and treat LTBI in new immigrants from countries of birth with an estimated TB incidence rate in excess of 50 per 100 000 person-years. If this strategy had been implemented in 1986, the national TB incidence rate would have fallen by 18.5%, from 5.4 to 4.4 cases per 100 000 population by 2002.

CONCLUSION

This study suggests that screening and treating LTBI in foreign-born persons from high TB incidence countries is the most effective strategy in terms of total persons screened and treated and percentage reduction in national incidence.

Sustained response to deep brain stimulation in LRRK2 parkinsonism with the Y1699C mutation

Although effective deep brain stimulation of the subthalamic nucleus (STN-DBS) is reported in G2019S leucine-rich repeat kinase 2 (LRRK2) parkinsonism, response to surgery in other LRRK2 mutations has not been previously reported. We present an affected individual from the Lincolnshire pedigree (Y1699C), on whom bilateral STN-DBS was performed to control severe motor fluctuations and dyskinesias. He showed a marked improvement in Unified Parkinson's Disease Rating Scale (UPDRS) Part III scores in the "on" and "off" states, sustained for more than three years. Bilateral STN-DBS in LRRK2-parkinsonism with the Y1699C mutation can be as effective as in sporadic PD.