HIV-associated tuberculosis and immigration in a high-income country: incidence trends and risk factors in recent years

HIV replication and tuberculosis risk among people living with HIV in Europe: A multicohort analysis, 1983-2015

INTRODUCTION

HIV replication leads to a change in lymphocyte phenotypes that impairs immune protection against opportunistic infections. We examined current HIV replication as an independent risk factor for tuberculosis (TB).

METHODS

We included people living with HIV from 25 European cohorts 1983-2015. Individuals <16 years or with previous TB were excluded. Person-time was calculated from enrolment (baseline) to the date of TB diagnosis or last follow-up information. We used adjusted Poisson regression and general additive regression models.

RESULTS

We included 272,548 people with a median follow-up of 5.9 years (interquartile range [IQR] 2.3-10.9). At baseline, the median CD4 cell count was 355 cells/μL (IQR 193-540) and the median HIV-RNA level 22,000 copies/mL (IQR 1,300-103,000). During 1,923,441 person-years of follow-up, 5,956 (2.2%) people developed TB. Overall, TB incidence was 3.1 per 1,000 person-years (95% confidence interval [CI] 3.02-3.18) and was four times higher in patients with HIV-RNA levels of 10,000 compared with levels <400 copies/mL in any CD4 stratum. CD4 and HIV-RNA time-updated analyses showed that the association between HIV-RNA and TB incidence was independent of CD4. The TB incidence rate ratio for people born in TB-endemic countries compared with those born in Europe was 1.8 (95% CI 1.5-2.2).

CONCLUSIONS

Our results indicate that ongoing HIV replication (suboptimal HIV control) is an important risk factor for TB, independent of CD4 count. Those at highest risk of TB are people from TB-endemic countries. Close monitoring and TB preventive therapy for people with suboptimal HIV control is important.

Incidence of and risk factors for tuberculosis among people with HIV on antiretroviral therapy in the United Kingdom

Objective:

The United Kingdom has a low tuberculosis incidence and earlier combination antiretroviral therapy (cART) is expected to have reduced incidence among people with HIV. Epidemiological patterns and risk factors for active tuberculosis were analysed over a 20-year period among people accessing HIV care at sites participating in the UK CHIC observational study.

Design:

Cohort analysis.

Methods:

Data were included for individuals over 15 years old attending for HIV care between 1996 and 2017 inclusive, with at least 3 months follow-up recorded. Incidence rates of new tuberculosis events were calculated and stratified by ethnicity (white/Black/other) as a proxy for tuberculosis exposure. Poisson regression models were used to determine the associations of calendar year, ethnicity and other potential risk factors after cART initiation.

Results:

Fifty-eight thousand seven hundred and seventy-six participants (26.3% women; 54.5% white, 32.0% Black, 13.5% other/unknown ethnicity; median (interquartile range) age 34 (29–42) years) were followed for 546 617 person-years. Seven hundred and four were treated for active tuberculosis [rate 1.3; 95% confidence interval (CI) 1.2–1.4/1000 person-years). Tuberculosis incidence decreased from 1.3 (1.2–1.5) to 0.6 (0.4–0.9)/1000 person-years from pre-2004 to 2011–2017. The decline among people of Black ethnicity was less steep than among those of white/other ethnicities, with incidence remaining high among Black participants in the latest period [2.1 (1.4–3.1)/1000 person-years]. Two hundred and eighty-three participants [191 (67%) Black African] had tuberculosis with viral load less than 50 copies/ml.

Conclusion:

Despite the known protective effect of cART against tuberculosis, a continuing disproportionately high incidence is seen among Black African people. Results support further interventions to prevent tuberculosis in this group.

Mortality of People Living with HIV in Paris Area from 2011 to 2015

In high-income countries, causes of death in people living with HIV (PLHIV) have changed. Three French national surveys from 2000 to 2010 showed a decrease in AIDS-related and an increase in non-AIDS-related deaths. Deaths notified in PLHIV followed between January 1, 2011 and December 31, 2015 in 1 of 13 participating hospitals northeast of Paris area were described. Risk factors for death were assessed, using a multivariable logistic regression model. Of 14,403 individuals, 295 died. Median age at death was 52 years (interquartile range = 47-60) and 77% were men. Sixty-seven individuals (23%) died from non-AIDS-defining nonviral hepatitis-related (NaNH) malignancy, 40 (14%) from AIDS, 34 (12%) from cardiovascular disease (CVD), 33 (11%) from non-AIDS infection, 21 (7%) from liver disease, and 12 (4%) from suicide. Men and women born in sub-Saharan Africa had a lower adjusted odds ratio (aOR) of dying than men having sex with men (MSM) born in France (0.70, 95% confidence interval = 0.45-1.09; and 0.45, 0.28-0.73, respectively). Risk factors for death were older age (aOR = 2.26, 1.36-3.77 for 40-49 years and 2.91, 1.75-4.84 for >50 years vs. 18-39 years), male intravenous drug users (IVDU) transmission (2.24, 1.42-3.54 vs. MSM born in France), AIDS (2.75, 2.10-3.59), antiretroviral therapy initiation in earlier periods, time since HIV diagnosis <1 year, low CD4 cell count nadir, hepatitis B virus and/or hepatitis C virus coinfection (1.69, 1.23-2.30), and psychiatric disorders (1.73, 1.27-2.38). Our study confirms the increasing frequency of non-AIDS-related deaths, mainly NaNH malignancies and CVD, in PLHIV, justifying overall and in some specific populations (psychiatric and IVDU) prevention and screening.

2018 Belgian guidelines for the screening for latent tuberculosis in HIV-infected patients

Objectives: To review the current knowledge on screening for latent tuberculosis infection (LTBI) in HIV-infected adults and provide specific guidelines for Belgium. Focus is given to who to test, which testing method to use, timing of screening and choice of LTBI treatment. Methods: Expert review by the members of the Belgian LTBI group, in consultancy with the ARC College. Results: Target population, timing of screening, testing method, active TB exclusion, treatment of LTBI and guideline implementation are all reviewed. Conclusions: The principal changes include a selective approach to screen for LTBI (screening only of the HIV-infected patients at highest risk of active TB) as well as the timing of screening (testing for LTBI performed only after immune-restauration by antiretroviral therapy).

HIV and tuberculosis co-infection among migrants in Europe: A systematic review on the prevalence, incidence and mortality

Background

International human migration has been rapidly growing. Migrants coming from low and middle income countries continue to be considerably vulnerable and at higher risk for infectious diseases, namely HIV (Human Immunodeficiency Virus) and tuberculosis (TB). In Europe, the number of patients with HIV-TB co-infection has been increasing and migration could be one of the potential driving forces.

Objective

This systematic review aims to improve the understanding on the burden of HIV-TB co-infection among migrants in Europe and to assess whether these populations are particularly vulnerable to this co-infection compared to nationals.

Design

MEDLINE^®, Web of Science^® and Scopus^® databases were searched from March to April 2016 using combinations of keywords. Titles and abstracts were screened and studies meeting the inclusion criteria proceeded for full-text revision. These articles were then selected for data extraction on the prevalence, incidence and mortality.

Results

The majority of HIV-TB prevalence data reported in the analysed studies, including extrapulmonary/disseminated TB forms, was higher among migrant vs. nationals, some of the studies even showing increasing trends over time. Additionally, while HIV-TB incidence rates have decreased among migrants and nationals, migrants are still at a higher risk for this co-infection. Migrants with HIV-TB co-infection were also more prone to unsuccessful treatment outcomes, death and drug resistant TB. However, contradicting results also showed lower mortality compared to nationals.

Conclusions

Overall, a disproportionate vulnerability of migrants to acquire the HIV-TB co-infection was observed across studies. Such vulnerability has been associated to low socioeconomic status, poor living conditions and limited access to healthcare. Adequate social support, early detection, appropriate treatment, and adequate access to healthcare are key improvements to tackle HIV-TB co-infection among these populations.

The diagnostic value of polymerase chain reaction for Mycobacterium tuberculosis to distinguish intestinal tuberculosis from crohn's disease: A meta-analysis

BACKGROUND/AIM

Intestinal tuberculosis (ITB) and Crohn's disease (CD) are important differential diagnoses that can be difficult to distinguish. Polymerase chain reaction (PCR) for Mycobacterium tuberculosis (MTB) is an efficient and promising tool. This meta-analysis was performed to systematically and objectively assess the potential diagnostic accuracy and clinical value of PCR for MTB in distinguishing ITB from CD.

MATERIALS AND METHODS

We searched PubMed, Embase, Web of Science, Science Direct, and the Cochrane Library for eligible studies, and nine articles with 12 groups of data were identified. The included studies were subjected to quality assessment using the revised Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.

RESULTS

The summary estimates were as follows: sensitivity 0.47 (95% CI: 0.42-0.51); specificity 0.95 (95% CI: 0.93-0.97); the positive likelihood ratio (PLR) 10.68 (95% CI: 6.98-16.35); the negative likelihood ratio (NLR) 0.49 (95% CI: 0.33-0.71); and diagnostic odds ratio (DOR) 21.92 (95% CI: 13.17-36.48). The area under the curve (AUC) was 0.9311, with a Q* value of 0.8664. Heterogeneity was found in the NLR. The heterogeneity of the studies was evaluated by meta-regression analysis and subgroup analysis.

CONCLUSIONS

The current evidence suggests that PCR for MTB is a promising and highly specific diagnostic method to distinguish ITB from CD. However, physicians should also keep in mind that negative results cannot exclude ITB for its low sensitivity. Additional prospective studies are needed to further evaluate the diagnostic accuracy of PCR.

Influence of geographic origin, sex, and HIV transmission group on the outcome of first-line combined antiretroviral therapy in France

BACKGROUND

More data are needed on the influence of geographic origin, sex, and the HIV transmission group on biological and clinical outcomes after first-line combined antiretroviral therapy (cART) initiation.

METHODS

We studied antiretroviral-naive HIV-1-infected adults enrolled in the French Hospital Database on HIV cohort in France and who started cART between 2006 and 2011. The censoring date of the study was 31 December 2012. According to geographic origin [French natives (FRA) or sub-Saharan Africa/non-French West Indies (SSA/NFW)], sex, and HIV transmission group, we assessed 2-year Kaplan-Meier probabilities and adjusted hazard ratios (aHRs) for plasma viral load undetectability and CD4 cell recovery, and 5-year cumulative incidences and aHRs for negative clinical outcomes (AIDS-defining event, serious non-AIDS events, or death).

RESULTS

Of 9746 eligible individuals, 7297 (74.9%) were FRA and 2449 (25.1%) were sub-Saharan Africa/non-French West Indies migrants. More migrants (38.1%) than nonmigrants (27.5%) started cART with a CD4 cell count less than 200/μl (P < 0.0001). By comparison with FRA MSM, nonhomosexual men, whatever their geographic origin, had lower aHRs for viral undetectability; all patient groups, particularly migrants, had lower aHRs for CD4 cell recovery than FRA MSM; aHRs for negative clinical outcome (360 new AIDS-defining events, 1376 serious non-AIDS events, 38 deaths) were also higher in nonhomosexual men, regardless of geographic origin. Preexisting AIDS status, a lower CD4 cell count and older age at cART initiation had the biggest impact on changes between the crude and aHRs of clinical outcomes.

CONCLUSION

Compared with FRA MSM, all migrants had a lower likelihood of CD4 cell recovery, and nonhomosexual men had a higher likelihood of negative virological and clinical outcomes.

Standard Genotyping Overestimates Transmission of Mycobacterium tuberculosis among Immigrants in a Low-Incidence Country

Immigrants from regions with a high incidence of tuberculosis (TB) are a risk group for TB in low-incidence countries such as Switzerland. In a previous analysis of a nationwide collection of 520 Mycobacterium tuberculosis isolates from 2000 to 2008, we identified 35 clusters comprising 90 patients based on standard genotyping (24-locus mycobacterial interspersed repetitive-unit-variable-number tandem-repeat [MIRU-VNTR] typing and spoligotyping). Here, we used whole-genome sequencing (WGS) to revisit these transmission clusters. Genome-based transmission clusters were defined as isolate pairs separated by ≤12 single nucleotide polymorphisms (SNPs). WGS confirmed 17/35 (49%) MIRU-VNTR typing clusters; the other 18 clusters contained pairs separated by >12 SNPs. Most transmission clusters (3/4) of Swiss-born patients were confirmed by WGS, as opposed to 25% (4/16) of the clusters involving only foreign-born patients. The overall clustering proportion was 17% (90 patients; 95% confidence interval [CI], 14 to 21%) by standard genotyping but only 8% (43 patients; 95% CI, 6 to 11%) by WGS. The clustering proportion was 17% (67/401; 95% CI, 13 to 21%) by standard genotyping and 7% (26/401; 95% CI, 4 to 9%) by WGS among foreign-born patients and 19% (23/119; 95% CI, 13 to 28%) and 14% (17/119; 95% CI, 9 to 22%), respectively, among Swiss-born patients. Using weighted logistic regression, we found weak evidence of an association between birth origin and transmission (adjusted odds ratio of 2.2 and 95% CI of 0.9 to 5.5 comparing Swiss-born patients to others). In conclusion, standard genotyping overestimated recent TB transmission in Switzerland compared to WGS, particularly among immigrants from regions with a high TB incidence, where genetically closely related strains often predominate. We recommend the use of WGS to identify transmission clusters in settings with a low incidence of TB.

Later cART initiation in migrant men from sub-Saharan Africa without advanced HIV disease in France

Objective

To compare the time from entry into care for HIV infection until combination antiretroviral therapy (cART) initiation between migrants and non migrants in France, excluding late access to care.

Methods

Antiretroviral-naïve HIV-1-infected individuals newly enrolled in the FHDH cohort between 2002–2010, with CD4 cell counts &gt;200/μL and no previous or current AIDS events were included. In three baseline CD4 cell count strata (200–349, 350-499, ≥500/μL), we examined the crude time until cART initiation within three years after enrolment according to geographic origin, and multivariable hazard ratios according to geographic origin, gender and HIV-transmission group, with adjustment for baseline age, enrolment period, region of care, plasma viral load, and HBV/HBC coinfection.

Results

Among 13338 individuals, 9605 (72.1%) were French natives (FRA), 2873 (21.4%) were migrants from sub-Saharan Africa/non-French West Indies (SSA/NFW), and 860 (6.5%) were migrants from other countries. Kaplan-Meier probabilities of cART initiation were significantly lower in SSA/NFW than in FRA individuals throughout the study period, regardless of the baseline CD4 stratum. After adjustment, the likelihood of cART initiation was respectively 15% (95%CI, 1–28) and 20% (95%CI, 2–38) lower in SSA/NFW men than in FRA men who had sex with men (MSM) in the 350-499 and ≥500 CD4 strata, while no difference was observed between other migrant groups and FRA MSM.

Conclusion

SSA/NFW migrant men living in France with CD4 &gt;350/μL at entry into care are more likely to begin cART later than FRA MSM, despite free access to treatment. Administrative delays in obtaining healthcare coverage do not appear to be responsible.

Attitudes about tuberculosis prevention in the elimination phase: a survey among physicians in Germany

Background

Targeted and stringent measures of tuberculosis prevention are necessary to achieve the goal of tuberculosis elimination in countries of low tuberculosis incidence.

Methods

We ascertained the knowledge about tuberculosis risk factors and stringency of tuberculosis prevention measures by a standardized questionnaire among physicians in Germany involved in the care of individuals from classical risk groups for tuberculosis.

Results

510 physicians responded to the online survey. Among 16 risk factors immunosuppressive therapy, HIV-infection and treatment with TNF-antagonist were thought to be the most important risk factors for the development of tuberculosis in Germany. Exposure to a patient with tuberculosis ranked on the 10^th position. In the event of a positive tuberculin-skin-test or interferon-γ release assay only 50%, 40%, 36% and 25% of physicians found that preventive chemotherapy was indicated for individuals undergoing tumor necrosis factor-antagonist therapy, close contacts of tuberculosis patients, HIV-infected individuals and migrants, respectively.

Conclusions

A remarkably low proportion of individuals with latent infection with Mycobacterium tuberculosis belonging to classical risk groups for tuberculosis are considered candidates for preventive chemotherapy in Germany. Better knowledge about the risk for tuberculosis in different groups and more stringent and targeted preventive interventions will probably be necessary to achieve tuberculosis elimination in Germany.

Incidence of HIV-associated tuberculosis among individuals taking combination antiretroviral therapy: a systematic review and meta-analysis

BACKGROUND

Knowledge of tuberculosis incidence and associated factors is required for the development and evaluation of strategies to reduce the burden of HIV-associated tuberculosis.

METHODS

Systematic literature review and meta-analysis of tuberculosis incidence rates among HIV-infected individuals taking combination antiretroviral therapy.

RESULTS

From PubMed, EMBASE and Global Index Medicus databases, 42 papers describing 43 cohorts (32 from high/intermediate and 11 from low tuberculosis burden settings) were included in the qualitative review and 33 in the quantitative review. Cohorts from high/intermediate burden settings were smaller in size, had lower median CD4 cell counts at study entry and fewer person-years of follow up. Tuberculosis incidence rates were higher in studies from Sub-Saharan Africa and from World Bank low/middle income countries. Tuberculosis incidence rates decreased with increasing CD4 count at study entry and duration on combination antiretroviral therapy. Summary estimates of tuberculosis incidence among individuals on combination antiretroviral therapy were higher for cohorts from high/intermediate burden settings compared to those from the low tuberculosis burden settings (4.17 per 100 person-years [95% Confidence Interval (CI) 3.39-5.14 per 100 person-years] vs. 0.4 per 100 person-years [95% CI 0.23-0.69 per 100 person-years]) with significant heterogeneity observed between the studies.

CONCLUSIONS

Tuberculosis incidence rates were high among individuals on combination antiretroviral therapy in high/intermediate burden settings. Interventions to prevent tuberculosis in this population should address geographical, socioeconomic and individual factors such as low CD4 counts and prior history of tuberculosis.

Tuberculosis among people living with HIV/AIDS in the German ClinSurv HIV Cohort: long-term incidence and risk factors

Background

Tuberculosis (TB) still presents a leading cause of morbidity and mortality among people living with HIV/AIDS (PLWHA), including those on antiretroviral therapy. In this study, we aimed to determine the long-term incidence density rate (IDR) of TB and risk factors among PLWHA in relation to combination antiretroviral therapy (cART)-status.

Methods

Data of PLWHA enrolled from 2001 through 2011 in the German ClinSurv HIV Cohort were investigated using survival analysis and Cox regression.

Results

TB was diagnosed in 233/11,693 PLWHA either at enrollment (N = 62) or during follow-up (N = 171). The TB IDR during follow-up was 0.37 cases per 100 person-years (PY) overall [95% CI, 0.32-0.43], and was higher among patients who never started cART and among patients originating from Sub-Saharan Africa (1.23 and 1.20 per 100PY, respectively). In two multivariable analyses, both patients (I) who never started cART and (II) those on cART shared the same risk factors for TB, namely: originating from Sub-Saharan Africa compared to Germany (I, hazard ratio (HR); [95% CI]) 4.05; [1.87-8.78] and II, HR 5.15 [2.76-9.60], CD4+ cell count <200 cells/μl (I, HR 8.22 [4.36-15.51] and II, HR 1.90 [1.14-3.15]) and viral load >5 log₁₀ copies/ml (I, HR 2.51 [1.33-4.75] and II, HR 1.77 [1.11-2.82]). Gender, age or HIV-transmission risk group were not independently associated with TB.

Conclusion

In the German ClinSurv HIV cohort, patients originating from Sub-Saharan Africa, with low CD4+ cell count or high viral load at enrollment were at increased risk of TB even after cART initiation. As patients might be latently infected with Mycobacterium tuberculosis complex, early screening for latent TB infection and implementing isoniazid preventive therapy in line with available recommendations is crucial.

Higher rates of AIDS during the first year of antiretroviral therapy among migrants: the importance of tuberculosis

OBJECTIVE

In lower-income countries rates of AIDS-defining events (ADEs) and death are high during the first year of combination antiretroviral therapy (ART). We investigated differences between foreign-born (migrant) and native-born (nonmigrant) patients initiating ART in Europe, the US and Canada, and examined rates of the most common ADEs and mortality during the first year of ART.

DESIGN

Observational cohort study.

METHODS

We studied HIV-positive adults participating in one of 12 cohorts in the Antiretroviral Therapy Cohort Collaboration (ART-CC).

RESULTS

Of 48 854 patients, 25.6% were migrants: 16.1% from sub-Saharan Africa, 5.6% Latin America, 2.3% North Africa/Middle East, and 1.6% Asia. Incidence of ADEs during the first year of ART was 60.8 per 1000 person-years: 69.9 for migrants and 57.7 for nonmigrants [crude hazard ratio (HR) 1.18; 95% confidence interval (CI) 1.08-1.29], adjusted HR (for sex, age, CD4, HIV-1 RNA, ART regimen, prior ADE, probable route of infection and year of initiation, and stratified by cohort) 1.21 (95% CI 1.09-1.34). Rates of tuberculosis were substantially higher in migrants than nonmigrants (14.3 vs. 6.3; adjusted HR 1.94; 95% CI 1.53-2.46). In contrast, mortality was higher among nonmigrants than migrants (crude HR 0.71; 95% CI 0.61-0.84), although excess mortality was partially explained by patient characteristics at start of ART (adjusted HR 0.91; 95% CI 0.76-1.09).

CONCLUSIONS

During the first year of ART, HIV-positive migrants had higher rates of ADEs than nonmigrants. Tuberculosis was the most common ADE among migrants, highlighting the importance of screening for tuberculosis prior to ART initiation in this population.

Utility of in vitro interferon-γ release assay in differential diagnosis between intestinal tuberculosis and Crohn's disease

OBJECTIVE

To evaluate the diagnostic utility of interferon-γ release assay (T-SPOT.TB) for the differential diagnosis between Crohn's disease (CD) and intestinal tuberculosis (ITB).

METHODS

A total of 103 CD and 88 ITB patients, confirmed by histology and anti-tuberculosis treatment response from 2003 to 2011, were included. Their characteristics and clinical features were recorded. Mycobacterium tuberculosis (MTB) polymerase chain reaction (PCR) of IS6110, in vitro T-SPOT.TB, tuberculin skin test (TST), immunoglobulin G (IgG) antibody to MTB (protein chip), serum anti-Saccharomyces cerevisiae antibodies (ASCA IgG, chronic inflammatory bowel disease profile) and acid-fast staining of biopsied colonic tissue specimens were performed. Statistical analysis was conducted to determine their concordance with the diagnosis and its sensitivity, specificity, positive (PPV) and negative predictive value (NPV).

RESULTS

Abnormal pulmonary X-ray, ascites and lesions of both cecum and ascending colon were more associated with ITB, while intestinal surgery and lesions of both ileum and adjacent colon were more commonly seen in CD. Significant diagnostic concordance was found using T-SPOT.TB (κ = 0.786) by consistency test. The sensitivity, specificity, PPV and NPV of T-SPOT.TB were 86%, 93%, 88% and 91%, respectively, and the sensitivity and NPV were significantly higher than other examinations (P < 0.05).

CONCLUSION

T-SPOT.TB is a valuable assay in differentiating ITB from CD, particularly in the diagnostic exclusion of ITB based on its high specificity and NPV.

HIV among immigrants living in high-income countries: a realist review of evidence to guide targeted approaches to behavioural HIV prevention

BACKGROUND

Immigrants from developing and middle-income countries are an emerging priority in HIV prevention in high-income countries. This may be explained in part by accelerating international migration and population mobility. However, it may also be due to the vulnerabilities of immigrants including social exclusion along with socioeconomic, cultural and language barriers to HIV prevention. Contemporary thinking on effective HIV prevention stresses the need for targeted approaches that adapt HIV prevention interventions according to the cultural context and population being addressed. This review of evidence sought to generate insights into targeted approaches in this emerging area of HIV prevention.

METHODS

We undertook a realist review to answer the research question: 'How are HIV prevention interventions in high-income countries adapted to suit immigrants' needs?' A key goal was to uncover underlying theories or mechanisms operating in behavioural HIV prevention interventions with immigrants, to uncover explanations as how and why they work (or not) for particular groups in particular contexts, and thus to refine the underlying theories. The realist review mapped seven initial mechanisms underlying culturally appropriate HIV prevention with immigrants. Evidence from intervention studies and qualitative studies found in systematic searches was then used to test and refine these seven mechanisms.

RESULTS

Thirty-four intervention studies and 40 qualitative studies contributed to the analysis and synthesis of evidence. The strongest evidence supported the role of 'consonance' mechanisms, indicating the pivotal need to incorporate cultural values into the intervention content. Moderate evidence was found to support the role of three other mechanisms - 'understanding', 'specificity' and 'embeddedness' - which indicated that using the language of immigrants, usually the 'mother tongue', targeting (in terms of ethnicity) and the use of settings were also critical elements in culturally appropriate HIV prevention. There was mixed evidence for the roles of 'authenticity' and 'framing' mechanisms and only partial evidence to support role of 'endorsement' mechanisms.

CONCLUSIONS

This realist review contributes to the explanatory framework of behavioural HIV prevention among immigrants living in high-income countries and, in particular, builds a greater understanding of the suite of mechanisms that underpin adaptations of interventions by the cultural context and population being targeted.

Impact of antiretroviral therapy on tuberculosis incidence among HIV-positive patients in high-income countries

BACKGROUND

The lower tuberculosis incidence reported in human immunodeficiency virus (HIV)-positive individuals receiving combined antiretroviral therapy (cART) is difficult to interpret causally. Furthermore, the role of unmasking immune reconstitution inflammatory syndrome (IRIS) is unclear. We aim to estimate the effect of cART on tuberculosis incidence in HIV-positive individuals in high-income countries.

METHODS

The HIV-CAUSAL Collaboration consisted of 12 cohorts from the United States and Europe of HIV-positive, ART-naive, AIDS-free individuals aged ≥18 years with baseline CD4 cell count and HIV RNA levels followed up from 1996 through 2007. We estimated hazard ratios (HRs) for cART versus no cART, adjusted for time-varying CD4 cell count and HIV RNA level via inverse probability weighting.

RESULTS

Of 65 121 individuals, 712 developed tuberculosis over 28 months of median follow-up (incidence, 3.0 cases per 1000 person-years). The HR for tuberculosis for cART versus no cART was 0.56 (95% confidence interval [CI], 0.44-0.72) overall, 1.04 (95% CI, 0.64-1.68) for individuals aged >50 years, and 1.46 (95% CI, 0.70-3.04) for people with a CD4 cell count of <50 cells/μL. Compared with people who had not started cART, HRs differed by time since cART initiation: 1.36 (95% CI, 0.98-1.89) for initiation <3 months ago and 0.44 (95% CI, 0.34-0.58) for initiation ≥3 months ago. Compared with people who had not initiated cART, HRs <3 months after cART initiation were 0.67 (95% CI, 0.38-1.18), 1.51 (95% CI, 0.98-2.31), and 3.20 (95% CI, 1.34-7.60) for people <35, 35-50, and >50 years old, respectively, and 2.30 (95% CI, 1.03-5.14) for people with a CD4 cell count of <50 cells/μL.

CONCLUSIONS

Tuberculosis incidence decreased after cART initiation but not among people >50 years old or with CD4 cell counts of <50 cells/μL. Despite an overall decrease in tuberculosis incidence, the increased rate during 3 months of ART suggests unmasking IRIS.

Latent tuberculosis infection in children: diagnostic approaches

Tuberculosis (TB) remains an important public health problem and a leading infectious cause of death. Diagnosis and treatment of latent tuberculosis infection (LTBI) is important for TB control and elimination. Nevertheless, the diagnosis of LTBI in both adults and children remains complex, since there is no gold standard. The development of interferon gamma release assays was a major breakthrough in the diagnosis of LTBI. The evaluation of IGRAs in the diagnosis of LTBI in children is proven to be difficult since childhood TB differs from adults as immune responses vary with age. Separate studies assessing IGRAs performance in children are still limited, and only a few of them divide results by narrow age groups Nevertheless, new approaches are being exploited by the ongoing research for the development of more efficient diagnostic tools. It is likely that many changes in both the diagnosis and management of LTBI will occur in the near future. We believe that better understanding of the immunopathology of latency can ultimately lead to the development of more effective strategies in TB control. In the present review we summarize current data on diagnosis of LTBI in children, underscoring the existing challenges and limitations.

Mycobacterium tuberculosis transmission in a country with low tuberculosis incidence: role of immigration and HIV infection

Immigrants from high-burden countries and HIV-coinfected individuals are risk groups for tuberculosis (TB) in countries with low TB incidence. Therefore, we studied their role in transmission of Mycobacterium tuberculosis in Switzerland. We included all TB patients from the Swiss HIV Cohort and a sample of patients from the national TB registry. We identified molecular clusters by spoligotyping and mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) analysis and used weighted logistic regression adjusted for age and sex to identify risk factors for clustering, taking sampling proportions into account. In total, we analyzed 520 TB cases diagnosed between 2000 and 2008; 401 were foreign born, and 113 were HIV coinfected. The Euro-American M. tuberculosis lineage dominated throughout the study period (378 strains; 72.7%), with no evidence for another lineage, such as the Beijing genotype, emerging. We identified 35 molecular clusters with 90 patients, indicating recent transmission; 31 clusters involved foreign-born patients, and 15 involved HIV-infected patients. Birth origin was not associated with clustering (adjusted odds ratio [aOR], 1.58; 95% confidence interval [CI], 0.73 to 3.43; P = 0.25, comparing Swiss-born with foreign-born patients), but clustering was reduced in HIV-infected patients (aOR, 0.49; 95% CI, 0.26 to 0.93; P = 0.030). Cavitary disease, male sex, and younger age were all associated with molecular clustering. In conclusion, most TB patients in Switzerland were foreign born, but transmission of M. tuberculosis was not more common among immigrants and was reduced in HIV-infected patients followed up in the national HIV cohort study. Continued access to health services and clinical follow-up will be essential to control TB in this population.

Tuberculosis among HIV-positive patients across Europe: changes over time and risk factors

OBJECTIVE

To describe temporal changes in the incidence rate of tuberculosis (TB) (pulmonary or extrapulmonary) among HIV-positive patients in western Europe and risk factors of TB across Europe.

METHODS

Poisson regression models were used to determine temporal changes in incidence rate of TB among 11,952 patients from western Europe (1994-2010), and to assess risk factors for TB among 12,673 patients from across Europe with follow-up after 2001.

RESULTS

Two hundred and seventy-seven TB events occurred during 84,221 person-years of follow-up (PYFU) in western Europe. The incidence rate declined from 1.91 [95% confidence interval (CI) 1.51-2.37)] in 1994-1995 to 0.12 (0.07-0.21)/100 PYFU in 2002-2003, and remained stable thereafter. After January 2001, 159 TB events were diagnosed; 65 cases in western Europe and 94 cases in eastern Europe; resulting in incidence rates of 0.12 (0.09-0.14) and 0.65 (0.52-0.79)/100 PYFU, respectively. In multivariable analysis, incidence rate of TB was approximately four-fold higher in eastern Europe compared with western Europe [incidence rate ratio (IRR) 4.25 (2.78-6.49), P < 0.001]. There were no significant temporal changes after 2001 and risk factors did not differ significantly between eastern Europe and western Europe. Lower CD4 cell counts, higher HIV-RNA levels, male sex, intravenous drug usage and African origin were all associated with higher risk of TB.

CONCLUSION

Incidence rates of TB in western Europe remained at a very low and stable level since 2001. After 2001, patients in eastern Europe were at substantially higher risk of TB than in western Europe. TB is of great concern in HIV-positive patients, especially in areas with high TB prevalence, high levels of immigration from TB-endemic regions, and with suboptimal access to combination antiretroviral therapy.

HIV and tuberculosis: a deadly human syndemic

A syndemic is defined as the convergence of two or more diseases that act synergistically to magnify the burden of disease. The intersection and syndemic interaction between the human immunodeficiency virus (HIV) and tuberculosis (TB) epidemics have had deadly consequences around the world. Without adequate control of the TB-HIV syndemic, the long-term TB elimination target set for 2050 will not be reached. There is an urgent need for additional resources and novel approaches for the diagnosis, treatment, and prevention of both HIV and TB. Moreover, multidisciplinary approaches that consider HIV and TB together, rather than as separate problems and diseases, will be necessary to prevent further worsening of the HIV-TB syndemic. This review examines current knowledge of the state and impact of the HIV-TB syndemic and reviews the epidemiological, clinical, cellular, and molecular interactions between HIV and TB.