Latent Tuberculosis Infection In Immigrants Research Articles

Optimizing tuberculosis screening for immigrants in southern New Brunswick: A pilot study protocol.

Immigrants from high tuberculosis-burdened countries have been shown to have an increased risk of latent tuberculosis infection (LTBI). To reduce the risk of increased tuberculosis cases in Canada, the country has a comprehensive immigration medical examination process that identifies individuals with active tuberculosis using chest X-ray; however, it fails to identify LTBI. The lack of LTBI identification is concerning because immigrants with LTBI are at an increased risk of developing active tuberculosis within their first few years of migration due to stressful experiences common to many immigrants. The goal of this pilot study is to improve the current LTBI screening protocols among immigrants from high tuberculosis incidence countries and to better prevent and manage tuberculosis cases, by introducing an LTBI screening pilot program. The objectives are threefold: 1) to screen LTBI in immigrants from high tuberculosis incidence countries, including immigrants identified as being at risk of LTBI by the NB health care system, using the QuantiFERON-TB Gold Plus interferon-gamma release assay (IGRA); 2) to offer LTBI treatment and supports to those identified as having LTBI; and 3) to assess immigrant and health care providers (HCPs) satisfaction of the LTBI screening pilot program. This cross-sectional study seeks to recruit 288 participants. Participants will be recruited via posters, social media platforms, invitations at immigrant wellness check-ups, presentations to local ethnocultural groups, and by snowball sampling. Consenting participants will be asked to submit a blood sample for LTBI screening; if positive, participants will be assessed and offered treatment for LTBI based on clinical assessment. Participants and HCPs' feedback will be gathered via short questionnaires. For the quantitative portion of the study, descriptive statistics will be used to summarize participant characteristics and feedback. Simultaneous logistic regression will be performed to identify variables associated with the IGRA test outcome and evidence of increased CD8 T-cell immune response among those found to be LTBI-positive. Qualitative results will be analyzed using inductive thematic analysis. The findings from this study will allow us to understand the role of the IGRA LTBI screening assay and its feasibility and acceptability by immigrants and HCPs in New Brunswick. The findings will additionally provide information on the enhancers and barriers of LTBI screening and management useful in determining how best to expand the LTBI screening program if deemed appropriate.

A Systematic Review on TST and IGRA Tests Used for Diagnosis of LTBI in Immigrants

High immigration rates from tuberculosis (TB) endemic countries to low-incidence countries have caused new TB guidelines in these countries to reconsider latent TB infection (LTBI) screening in these immigrants. We performed a systematic review with the primary outcome of evaluating the number of cases recommended LTBI treatment with the tuberculin skin test (TST) or interferon gamma release assay (IGRA). Secondary objectives were to examine prevalence of positive LTBI diagnostic tests stratified by age and incidence of TB in country of origin. We performed a systematic search of seven electronic databases for studies assessing TST and/or IGRA performance in immigrant populations to low incidence countries. Demographics, LTBI diagnosis, longitudinal TB development, and test result data were the primary data extracted from the studies. Prevalence of positive test data was stratified by age and country of origin. Studies were evaluated using a modified SIGN checklist for diagnostic studies. Data was compared using Fisher's exact test or χ (2) test, where appropriate. Our literature search yielded 51 studies (n = 34 TST, n = 9 IGRA, n = 8 both). Recommendation of LTBI treatment was less common in those tested with an IGRA compared to TST (p < 0.0001), while long-term development of active TB appears higher in those with a positive IGRA. There was no difference in the sensitivity and specificity of the IGRA and TST for prevalent TB (p > 0.05). Prevalence of a positive test was significantly lower in those who were <18 years of age compared to those ≥18 years of age (p < 0.0001) and those from low TB incidence countries compared to high incidence countries (p < 0.0001) for both TST and IGRA. When comparing the two tests within the 2 subgroups: age and TB incidence in country of origin, the prevalence of positive results was significantly lower for the IGRA than the TST (p < 0.0001). The number of available studies evaluating the IGRA and longitudinal active TB development in those tested limits this study. Prevalence of positive test results were significantly lower in immigrants who were tested with an IGRA, resulting in fewer immigrants being recommended for LTBI treatment compared to TST. Coupled with comparable performance for detecting prevalent TB cases, the IGRA appears to exhibit better specificity than the TST and may be preferred as the standard of care for detecting LTBI in immigrants moving to low TB incidence countries.

Can Australia eliminate TB? Modelling immigration strategies for reaching MDG targets in a low‐transmission setting

Background:The 2050 Millennium Development Goals (MDG) for tuberculosis (TB) aim for elimination of TB as a public health issue. We used a mathematical modelling approach to evaluate the feasibility of this target in a low‐prevalence setting with immigration‐related strategies directed at latent tuberculosis. Methods:We used a stochastic individual‐based model to simulate tuberculosis disease among immigrants to Victoria, Australia; a representative low‐transmission setting. A variety of screening and treatment approaches aimed at preventing reactivation of latent infection were applied to evaluate overall tuberculosis incidence reduction and rates of multidrug resistant disease. Results:Without additional intervention, tuberculosis incidence was predicted to reach 34.5 cases/million by 2050. Strategies involving the introduction of an available screening/treatment combination reduced TB incidence to between 16.9–23.8 cases/million, and required screening of 136–427 new arrivals for each case of TB prevented. Limiting screening to higher incidence regions of origin was less effective but more efficient. Conclusions:Public health strategies targeting latent tuberculosis infection in immigrants may substantially reduce tuberculosis incidence in a low prevalence region. However, immigration‐focused strategies cannot achieve the 2050 MDG and alternative or complementary approaches are required.

Screening of immigrants in the UK for latent tuberculosis

Evaluation of: Pareek M, Watson JP, Ormerod LP et al. Screening of immigrants in the UK for imported latent tuberculosis: a multicentre cohort study and cost–effectiveness analysis. Lancet Infect. Dis. 11(6), 435–444 (2011).Tuberculosis (TB) is a serious public health problem in the UK, and detection and prophylactic treatment of latent infection offers improved control. A recent study advocates the use of IFN-γ release assays to detect latent TB infection in immigrants to the UK under 35 years of age and suggests that such a program would be most cost effective if targeted at new entrants from high burden countries. We discuss these findings in the light of recently updated UK and European guidelines. We conclude that while action to contain TB in the UK is urgently needed, further evidence is required to assess the impact and cost–effectiveness of screening algorithms for latent infection.

Screening of immigrants in the UK for imported latent tuberculosis: a multicentre cohort study and cost-effectiveness analysis

SummaryBackgroundContinuing rises in tuberculosis notifications in the UK are attributable to cases in foreign-born immigrants. National guidance for immigrant screening is hampered by a lack of data about the prevalence of, and risk factors for, latent tuberculosis infection in immigrants. We aimed to determine the prevalence of latent infection in immigrants to the UK to define which groups should be screened and to quantify cost-effectiveness.MethodsIn our multicentre cohort study and cost-effectiveness analysis we analysed demographic and test results from three centres in the UK (from 2008 to 2010) that used interferon-γ release-assay (IGRA) to screen immigrants aged 35 years or younger for latent tuberculosis infection. We assessed factors associated with latent infection by use of logistic regression and calculated the yields and cost-effectiveness of screening at different levels of tuberculosis incidence in immigrants' countries of origin with a decision analysis model.FindingsResults for IGRA-based screening were positive in 245 of 1229 immigrants (20%), negative in 982 (80%), and indeterminate in two (0·2%). Positive results were independently associated with increases in tuberculosis incidence in immigrants' countries of origin (p=0·0006), male sex (p=0·046), and age (p<0·0001). National policy thus far would fail to detect 71% of individuals with latent infection. The two most cost-effective strategies were to screen individuals from countries with a tuberculosis incidence of more than 250 cases per 100 000 (incremental cost-effectiveness ratio [ICER] was £17 956 [£1=US$1·60] per prevented case of tuberculosis) and at more than 150 cases per 100 000 (including immigrants from the Indian subcontinent), which identified 92% of infected immigrants and prevented an additional 29 cases at an ICER of £20 819 per additional case averted.InterpretationScreening for latent infection can be implemented cost-effectively at a level of incidence that identifies most immigrants with latent tuberculosis, thereby preventing substantial numbers of future cases of active tuberculosis.FundingMedical Research Council and Wellcome Trust.

S5 Prevalence of latent tuberculosis infection in immigrants to the UK: findings from a multi-centre study

<h3>Background</h3> Notifications for tuberculosis (TB) in the United Kingdom (UK) increased by 30% between 1992 and 2007 with overseas-born migrants accounting for 72% of cases in 2007. Much of this increase is due to the synergy of migration from high-TB burden countries and the reactivation of pre-existing latent TB infection (LTBI). Since 2006, NICE guidance advocates screening for LTBI in all children from countries with a TB incidence &gt;40/100 000 and adults from Sub-Saharan Africa and countries with a TB incidence &gt;500/100 000. The rationale underpinning these guidelines remains unclear particularly as there are little data on the prevalence of LTBI in immigrants to the UK from regions with different TB incidence rates. <h3>Aims</h3> To quantify the prevalence of LTBI in immigrants, assess factors associated with IGRA positivity and to determine LTBI yield from current screening thresholds recommended by NICE. <h3>Methods</h3> Analysis of data prospectively obtained through IGRA testing (QuantiFERON-Gold/QuantiFERON-Gold-in-tube) of immigrants in three different centres in the UK during 2008–2010. Descriptive analyses were undertaken. Yields at different screening thresholds were calculated. Subsequent univariate and multivariate analyses were undertaken to assess independent factors associated with IGRA positivity; p&lt;0.05 considered significant. <h3>Results</h3> In total 915 immigrants were screened during the study period. Median age was 26.8 years (interquartile range 22–33), 50.6% were female and 72.5% had previously been BCG vaccinated. 48.9% and 28.5% of migrants screened originated from the Indian Subcontinent and Sub-Saharan Africa, respectively. Overall 911/915 individuals had determinate IGRA results—199 (21.7%) tested positive and 712 (77.8%) tested negative; 4 (0.4%) individuals had indeterminate results. Multivariate analysis revealed that increasing age (p&lt;0.0001) and increasing TB incidence of country of origin (p=0.0014) were independently associated with IGRA positivity. Applying current NICE guidance resulted in a yield of 76/311 (24.4%) but would miss 61.8% of the immigrant population with LTBI (Abstract S5 Table 1). <h3>Conclusions</h3> Immigrants have a high prevalence of LTBI but current NICE guidance detects only 38.2% of new entrants with LTBI. Given the high rates of reactivation of LTBI in new entrants, our findings suggest that consideration should be given to reducing the screening threshold to include those from the Indian Subcontinent (incidence 170/100 000) which would result in 67.8% of all LTBI cases being identified.

Vitamin D Deficiency Is Associated with Tuberculosis and Latent Tuberculosis Infection in Immigrants from Sub-Saharan Africa

Among African immigrants in Melbourne, Victoria, Australia, we demonstrated lower geometric mean vitamin D levels in immigrants with latent tuberculosis infection than in those with no Mycobacterium tuberculosis infection (P=.007); such levels were also lower in immigrants with tuberculosis or past tuberculosis than in those with latent tuberculosis infection (P=.001). Higher vitamin D levels were associated with lower probability of any M. tuberculosis infection (P=.001) and lower probability of tuberculosis or past tuberculosis (compared with latent tuberculosis infection; P=.001).

QuantiFERON ®-TB Gold test in the identification of latent tuberculosis infection in immigrants

The identification and treatment of latent tuberculosis infection (LTBI) among immigrants are an effective strategy for TB control in developed countries. A new test for LTBI identification that uses more specific antigens of Mycobacterium tuberculosis is now commercially available under the brand name of QuantiFERON-TB Gold test. To compare QuantiFERON-TB Gold test to tuberculin skin testing (TST) for the detection of LTBI among immigrants from high endemic TB areas. Undocumented immigrants attending a district medical center were enrolled if they originated from high endemic TB areas, the time of arrival in Italy was < or = 5 years, had neither active TB disease nor known immunodeficiency status. The TST was applied according to standards and QuantiFERON-TB Gold test was performed following the manufacturer's instructions. Hundred subjects were included in the comparative analysis. TST was positive in 44% of subjects; 15% had a positive QuantiFERON-TB Gold test result. The total agreement between TST and QuantiFERON-TB Gold test was 71%, for a kappa statistics of 0.37; agreement was 100% for TST negative results, but only 34% for TST positive ones. In the multivariate logistic regression analysis, previous BCG vaccination was independently associated with a lower chance of disagreement between the tests. The prevalence of LTBI among immigrants was lower when determined by QuantiFERON-TB Gold; this may be a consequence of more specific MTB antigens used. Our results suggest that QuantiFERON-TB Gold may be used as confirmatory test for TST positive immigrants candidate to preventive therapy.

Estudio de los factores asociados a la infección tuberculosa latente en inmigrantes menores de 35 años

To analyze the prevalence of latent tuberculosis infection in immigrants. A review was performed of patients less than 35 years old who were seen in an imported disease unit in Barcelona (Spain). A total of 837 tuberculin tests were performed, 728 were read and 351 (48.2%) cases of latent tuberculosis infection were detected. Older patients and those from Africa showed the highest prevalence. Immigrants in our setting present a high prevalence of latent tuberculosis infection. Few patients follow all the indications, making it necessary to improve strategies directed toward screening and diagnosis, as well as prescription and compliance with preventive treatment.

Detecting and treating tuberculosis infection in immigrants from developing countries were cost-effective

Source Citation Khan K, Muennig P, Behta M, Zivin JG. Global drug-resistance patterns and the management of latent tuberculosis infection in immigrants to the United States. N Engl J Med. 2002;347:1850-9. 12466510

Global drug-resistance patterns and the management of latent tuberculosis infection in immigrants to the United States.

In the United States, an increasingly disproportionate burden of tuberculosis among the foreign-born population has led to calls for improvements in the detection and treatment of latent infection in new immigrants. Current treatment guidelines do not take into account global differences in drug-resistance patterns or their implications for the treatment of immigrants. The use of multinational surveillance systems to guide the management of latent infection according to region-specific drug-resistance profiles could improve the efficiency of efforts to reduce the burden of tuberculosis in immigrants to the United States. We constructed a decision-analysis model by using a hypothetical cohort of all documented immigrants entering the United States from developing nations. Region-specific drug-resistance profiles were derived from data on 30,388 cases of infection. The model examined the effectiveness and cost effectiveness of four strategies: no intervention or tuberculin skin testing followed by treatment with isoniazid, treatment with rifampin, or treatment with rifampin plus pyrazinamide for those with a positive test result. A strategy of detecting and treating latent tuberculosis infection was cost-saving among immigrants from Mexico, Haiti, sub-Saharan Africa, South Asia, and developing nations in East Asia and the Pacific. This strategy was highly cost effective among immigrants from other developing nations. Rifampin plus pyrazinamide was the preferred strategy for treating latent infection in immigrants from Vietnam, Haiti, and the Philippines. For new immigrants to the United States from developing nations, a strategy of detecting and treating latent tuberculosis infection would lead to substantial health and economic benefits. Because of the high prevalence of resistance to isoniazid, treatment with a rifampin-containing regimen should be strongly considered for immigrants from Vietnam, Haiti, and the Philippines.

Mandatory screening and treatment of immigrants for latent tuberculosis in the USA: just restraint?

A report by the Institute of Medicine, Ending Neglect, and sponsored by the US Centers for Disease Control and Prevention, makes recommendations for achieving elimination of tuberculosis in the USA. Among them is the recommendation that a mandatory screening programme be introduced for latent tuberculosis infection in immigrants from high prevalence countries, and that the provision of a permanent residence card (green card) be linked to the completion of an approved course of preventive treatment. We examine the evidence put forward to support this proposal and assess whether such a mandatory programme for preventive treatment of individuals, who do not pose an immediate risk but could pose a risk in the future, meets internationally recognised standards for coercive public-health measures. We conclude from our analysis that there is reason to question (i) the risk analysis, (ii) the estimates of effectiveness of such a policy, (iii) the cost calculations, and (iv) the operational consequences put forward in the report. Moreover, we show that international standards for mandatory screening and treatment are not met.