Prevalence of Latent Mycobacterium Tuberculosis Infection (LTBI) in Saudi Arabia; Population based survey

The risk of tuberculosis infection in Saudi patients receiving adalimumab, etanercept, and tocilizumab therapy

BACKGROUND

The risk of infection including tuberculosis (TB) infection or reactivation during biological therapy with the current various clinical application is a major concern. This risk may be higher in countries endemic to TB. Our aim of this study is to determine the risk of TB infection in patients receiving 3 biological treatments, Adalimumab, Etanercept and Tocilizumab.

METHODS

A retrospective cohort study extending over 2 years follow-up for all patients receiving Adalimumab, Etanercept and Tocilizumab for various clinical indications in a tertiary care center in Saudi Arabia.

RESULT

Over the period of 2015-2019, A total of 410 patients received Adalimumab, 271 received Etanercept and 58 patients received Tocilizumab. Rheumatoid arthritis was the most common indication for therapy in all groups and for Adalimumab the most common indication was inflammatory bowel disease, for Etanercept was psoriatic arthritis and for Tocilizumab was juvenile idiopathic arthritis. After a mean follow up period of 36 ± 8.9 months for patients receiving Adalimumab, 21.5 ± 8.4 months for patients receiving Etanercept and 21 ± 2.5 months for patients receiving Tocilizumab there were no reported cases of TB infection in all groups. Only one patient was diagnosed with latent TB 7 months later after starting Adalimumab and tow patients after starting Etanercept. The overall Interferon Gamma Release Assays (IGRA) positivity rate was 9.7%. There was significant association between IGRA positivity rate and patient age. The cutoff age in which IGRA positivity has significantly increased was 53.20 years.

CONCLUSION

In our study, patients receiving Etanercept, Adalimumab and Tocilizumab had no increased risk of TB infection. Only 0.3% of patients treated with Adalimumab and 0.9% of patients treated with Etanercept converted to a positive IGRA during therapy.

Prevalence of Latent Tuberculosis Infection Among Nurses Working in Critical Areas at a Tertiary Care Hospital in Riyadh, Saudi Arabia

Introduction Tuberculosis is a critical health issue worldwide. Most infected persons are asymptomatic and categorized as having a latent tuberculosis infection (LTBI). Healthcare workers (HCWs) are more prone to being infected with tuberculosis and should be enrolled in a screening program for early detection. Objectives The study aims to estimate the prevalence of LTBI among nurses working in critical areas which include adult intensive care units, pediatric intensive care units, emergency departments, oncology departments, dialysis departments, tuberculosis labs, isolation rooms, and cardiac center intensive care units. Methods A record-based cross-sectional survey measured the prevalence of LTBI among nurses working in critical areas at Prince Sultan Military Medical City (PSMMC), Riyadh, Saudi Arabia. We reviewed the occupational health records of all nurses working in critical areas from June 1, 2021, to June 1, 2022. We recorded the data reviewed throughout the year in the Occupational Health Department at PSMMC. We excluded all participants with previously documented positive tuberculin skin test (TST) from the study. We analyzed the sociodemographic data, working years, working location, job title, and TST results. Results We included a total of 771 out of 2025 nurses in this study. Participants were mostly women (88%) and in the 26-35-year age group (67.7%). Most of the participants were originally from the Philippines (66.3%). The overall LTBI prevalence among nurses was 34.5%. The highest prevalence of LTBI was among nurses working in the cardiac intensive care unit (53.5%), and the lowest prevalence was among nurses working in the isolation department (8.9%; p-value <0.0001). Those who worked more in the hospital were significantly more infected with LTBI (p-value <0.04). Conclusion LTBI remains a significant health risk worldwide and in the Middle East as well as among HCWs. This underscores the necessity of comprehensive pre-hiring screening, annual screening, infection control protocols, and active management of HCWs with LTBI.

Prevalence of latent tuberculosis infection in Asian nations: A systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) is a serious public health concern around the world including Asia. TB burden is high in Asian countries and significant population harbor latent tuberculosis infection(LTBI).

AIM

This systematic review and meta-analysis aims to evaluate the prevalence of LTBI in Asian countries.

METHOD

We performed a systematic literature search on PubMed, Embase, and ScienceDirect to identify relevant articles published between January 1, 2005, and January 1, 2023 investigating the overall prevalence of latent TB among people of Asia. Subgroup analysis was done for Asian subregions during the study period of 2011 to 2016 and 2017 to 2023, for tuberculin skin test (TST) and interferon gamma release assay (IGRA), respectively, as well as for QuantiFERON-TB (QFT) and TSPOT TB tests. Der Simonian and Laird's random-effects model was used to pool the prevalence of LTBI found using TST and IGRA.

RESULT

A total of 15 studies were included after a systematic search from standard electronic databases. The analysis showed that the prevalence of latent TB in Asia was 21% (95% confidence interval [CI]: 19%-23%) and 36% (95% CI: 12%-59%) according to IGRAs and TSTs (cut off 10 mm) results, respectively. Based on IGRA, the prevalence of latent TB was 20% (95% CI: 13%-25%) in 2011 to 2016 and 21% (95% CI: 18%-24%) in 2017 to 2023. Using QFT, the prevalence was 19% (95% CI: 17%-22%) and using TSPOT, the prevalence was 26% (95% CI: 21%-31%). According to the United Nations division of Asia, the prevalence was higher for the Southern region and least for the Western region using TST and higher in the South-Eastern region and least in the Western region using the IGRA test.

CONCLUSION

Almost a quarter of the Asian population has LTBI. Its diagnosis often poses a diagnostic challenge due to the unavailability of standard test in certain areas. Given this prevalence, a mass screening program is suggested with the available standard test and public awareness along with anti-TB regimen should be considered for individuals who test positive. However, for it to be implemented effectively, we need to take the affordability, availability, and cost-effectiveness of such interventions into account.

Prevalence and factors associated with tuberculosis infection in India

BACKGROUND

The risk of tuberculosis (TB) disease is higher in individuals with TB infection. In a TB endemic country like India, it is essential to understand the current burden of TB infection at the population level. The objective of the present analysis is to estimate the prevalence of TB infection in India and to explore the factors associated with TB infection.

METHODS

Individuals aged > 15 years in the recently completed National TB prevalence survey in India who were tested for TB infection by QuantiFERON-TB Gold Plus (QFT-Plus) assay were considered for this sub-analysis. TB infection was defined as positive by QFT-Plus (value >0.35 IU/ml). The estimates for prevalence, prevalence ratio (PR) and adjusted risk ratio (aRR) estimates with 95% confidence intervals (CIs) were calculated.

RESULTS

Of the 16864 individuals analysed, the prevalence of TB infection was 22.6% (95% CI:19.4 -25.8). Factors more likely to be associated with TB infection include age > 30 years (aRR:1.49;95% CI:1.29-1.73), being male (aRR:1.26; 95%CI: 1.18-1.34), residing in urban location (aRR:1.58; 95%CI: 1.03-2.43) and past history of TB (aRR:1.49; 95%CI: 1.26-1.76).

CONCLUSION

About one fourth (22.6%) of the individuals were infected with TB in India. Individuals aged > 30 years, males, residing in urban location, and those with past history of TB were more likely to have TB infection. Targeted interventions for prevention of TB and close monitoring are essential to reduce the burden of TB in India.

Assessment of Knowledge, Attitude, and Practice towards Tuberculosis among Taif University Students

Tuberculosis (TB) remains a significant public health concern worldwide. Given the dense living and interactive nature of university environments, students may be at higher risk. This cross-sectional study assessed tuberculosis-related knowledge, attitudes, and practices (KAP) among students at Taif University (TU) from November 2022 to May 2023. Using a self-administered online questionnaire with 40 items, 1155 students participated. Key demographics: 68.2% females, 96.9% Saudi citizens, 94.5% unmarried, and 87.5% non-smokers. Of the respondents, 26.5% had no knowledge of TB. The TB-related KAP scores among the aware students were 64.9%, 74.8%, and 81%, respectively. Medical college students exhibited significantly higher TB-related knowledge and attitudes than their non-medical peers (p < 0.001). The findings indicate a commendable level of TB-awareness among TU students, but there remains a substantial uninformed segment. Campaigns to enhance TB knowledge among TU students are suggested.

The Risk of Latent Tuberculosis Infection Among Healthcare Workers at a General Hospital in Bisha, the Kingdom of Saudi Arabia

Background and objective Tuberculosis (TB) is a global health issue, often preceded by a latent tuberculosis infection (LTBI) in individuals. Significant global and local efforts have recently been directed toward this infection, focusing on TB control and eradication. This study aimed to assess the magnitude of LTBI among healthcare workers (HCWs) in the Kingdom of Saudi Arabia, by evaluating its prevalence and associated risk factors. Methods An analytical cross-sectional study was conducted among HCWs at the King Abdullah Hospital (KAH), from January to August 2018, by using two surveys: the first one involved data related to HCW demographics and the tuberculin skin test (TST) readings, and the second involved a questionnaire that assessed LTBI risk factors. Results Out of the total 561 HCWs who participated in the study, 66 had an induration reading of more than 10 mm in TST. Many factors were associated with LTBI cases, but multivariate analysis showed that age, gender, and nationality were statistically significant risk factors. Conclusion Given the nature of their work, HCWs are at a greater risk of TB and LTBI. At the same time, HCWs are uniquely positioned to play a crucial role in halting the spread of TB. Gaps in preventive measures may result in the increased spread of TB. Our study assessed risk factors associated with the increased risk of LTBI and proposed possible ways of addressing them.

The Prevalence of Mycobacterium tuberculosis Infection Among Cancer Patients Receiving Chemotherapy in a Tertiary Care Center

OBJECTIVE

To estimate the prevalence of tuberculosis (TB) infection among patients receiving cancer chemotherapy and to identify risk factors for latent TB reactivation.

METHODS

A cross-sectional study was conducted at a tertiary care center in Jeddah, Saudi Arabia. Patients were surveyed for TB risk factors, their records were reviewed for previous TB infection or disease, and blood samples were collected for interferon-gamma release assays (IGRAs).

RESULTS

A total of 203 patients were included. One hundred and twenty-five were females (62%). Median age was 52 years, and mean age was significantly higher in positive IGRA patients compared to negative IGRA (57.32 vs. 47.27; p = 0.009). Twenty-five patients (12.3%) had evidence of TB infection, 16 (68%) among them had a latent TB infection, while the rest received treatment for an active TB disease. The rate of active disease among cancer patients was 8 (3.9%). Additionally, 92% (23) of those with positive IGRA had solid cancers (p = 0.007), and all active TB cases occurred in this group of solid cancers.

CONCLUSION

TB prevalence was higher in chemotherapy patients compared to the general Saudi population. Patients with solid tumors and older age had a greater risk of developing the infection, signifying the importance of preventing TB and malignancy coexistence by initiating screening policies in cancer patients.

Management of Latent Tuberculosis Infection in Saudi Arabia: Knowledge and Perceptions Among Healthcare Workers

Background

Tuberculosis (TB) continues to pose a serious threat to public health despite great efforts. For many years, management and screening for active TB cases have been the main focus of TB control programs. Latent TB is a stage where TB can be prevented and controlled. Therefore, designing a comprehensive TB control program that includes latent tuberculosis infection (LTBI) management diseases is needed to be implemented among the healthcare workers (HCWs) who have been found to be at a higher risk for active TB compared to the general population.

The objective of the study

The objective of the study is to assess the knowledge and perceptions of LTBI among HCWs. In addition to estimating the prevalence of LTBI among HCWs using closed-end questions in a self-administered questionnaire.

Subjects and methods

Through a cross-sectional study and non-random sampling technique, 324 (84%) healthcare workers who met the inclusion criteria completed and submitted the electronic questionnaire.

Results

Among all participants, the study reported a good knowledge about LTBI; however, a third of HCWs had poor knowledge about the difference between LTBI and active TB. Eighteen percent of participants were diagnosed with LTBI, and two-thirds accepted the treatment. Of all participants who started the treatment, 55% completed the treatment course. The compliance rate was high among young HCWs and physicians who had a short course of LTB treatment regimen. 

Conclusion

The study reported a low acceptance and completion rate of LTBI therapy among HCWs. Low knowledge about some clinical facts of LTBI, the long duration of treatment, and being the treatment optional in Saudi health institutes were all barriers to accepting and completing the treatment of LTBI. All of these factors need to be addressed to increase the compliance rate to LTBI treatment.

The risk of tuberculosis infection in 410 Saudipatients receiving adalimumab therapy

BACKGROUND

Adalimumab is a fully humanized monoclonal antibody inhibitor of tumor necrosis factor-a used to treat various autoimmune disorders. Adalimumab poses a risk for tuberculosis (TB) infection, especially in countries where TB is endemic.

OBJECTIVE

Determine the rate of TB infection after adalimumab therapy in Saudi Arabia.

DESIGN

Medical record review.

SETTINGS

Tertiary care center in Riyadh.

PATIENTS AND METHODS

Demographic and clinical data were retrieved from the electronic healthcare records of all patients who received adalimumab treatment from 2015 to 2019.

MAIN OUTCOME MEASURES

Occurrence of TB after adalimumab therapy.

SAMPLE SIZE

410 patients (median ([QR] age, 37 [28], range 4-81 years), 40% males RESULTS: Rheumatoid arthritis was the most frequent indication (n=153, 37%). The patients were followed for a mean of 36 (8.9) months. No case of TB infection or reactivation was observed. An inter-feron-gamma release assay (IGRA) was requested in 353/391 (90.3%) patients, prior to initiating therapy. The IGRA was positive in 26 cases (6.6%). The IGRA-positive patients received isoniazid prophylactically. Bacterial infectious complications of adalimumab therapy occurred in 12 (2.9%) patients. Urinary tract infection was the most frequent complication (culture requested in 48 patients, positive in 8).

CONCLUSION

Adalimumab treatment was not associated with a risk of TB disease or TB reactivation in our cohort over the follow-up observation period. No TB reactivation occurred with adalimumab therapy when TB prophylaxis was used. The positive IGRA rate in patients on adalimumab treatment was low (7%).

LIMITATIONS

Single center and one geographical area in Saudi Arabia.

CONFLICT OF INTEREST

None.

Prevalence of Latent Tuberculosis Infection in the Middle East and North Africa: A Systematic Review

OBJECTIVE

Data on the prevalence of latent tuberculosis infection (LTBI) in Middle Eastern and North African countries are scarce. We aimed to review all relevant published data in countries belonging to this region to determine the overall prevalence of LTBI in the Middle East and North Africa (MENA) region.

METHODS

In this systematic review PubMed and Google Scholar databases were searched for observational, prospective, retrospective, cross-sectional, and cohort studies providing prevalence data of LTBI in any MENA country. Studies fulfilling the search criteria were incorporated in the review. Overall prevalence of LTBI with 95% confidence intervals (CI) was calculated using the random-effects model; heterogeneity was assessed using I 2 statistics. Gender and age group-based subgroup analyses were performed to evaluate the basis of heterogeneity.

RESULTS

The total number of overall LTBI studies identified was 956, of which 31 studies from ten countries within the MENA region were included that represented 12,439 subjects. The overall prevalence was 41.78% (95% CI 31.18% to 52.78%, I 2 = 99.31%). By gender-based subgroup analysis, the prevalence of LTBI was 33.12% (95% CI 18.97% to 49.04%, I 2 = 99.25%) and 32.65% (95% CI 19.79% to 47%, I 2 = 98.89%) in males and females, respectively, while in the age-based subgroup analysis, the prevalence of LTBI was 0.44% (95% CI -0.05% to 0.9%), 3.37% (95% CI 2.23% to 4.74%, I 2 = 0%), and 43.81% (95% CI 33.09% to 54.82%, I 2 = 99.18%) for children, adolescents, and adults, respectively.

CONCLUSION

This systematic review reveals a high prevalence of LTBI in the MENA region; enhanced LTBI surveillance and prompt infection prevention steps are urgently needed to prevent active tuberculosis, this would help achieve the World Health Organization End TB Strategy 2035, and the United Nations Sustainable Development Goals 2030 target in the MENA region.

Latent tuberculosis infection among health-care workers using Quantiferon-TB Gold-Plus in a country with a low burden for tuberculosis: prevalence and risk factors

BACKGROUND

Health-care workers (HCW) are susceptible to latent tuberculosis infection (LTBI). The prevalence of LTBI in HCW in Saudi Arabia has not been reported using the fourth-generation interferon gamma release assay QuantiFERON-TB Gold Plus (QFT-Plus).

OBJECTIVE

Determine the prevalence of LTBI in a large heterogeneous HCW population and assess risk factors for LTBI.

DESIGN

Cross-sectional and case-control study.

SETTING

Tertiary academic hospital, Riyadh, Saudi Arabia.

PATIENTS AND METHODS

Medical records of HCWs who had QFT-Plus performed between January to December 2018 were reviewed and included in the cross-sectional study. In a subset analysis, randomly selected positive QFT-Plus cases were compared with controls selected from the same areas of work. Univariate and binary logistic regression analyses were performed to assess the significance of other factors to QFT-PLus positivity.

MAIN OUTCOME MEASURES

Prevalence of LTBI in HCWs and potential risk factors for LTBI.

SAMPLE SIZE

3024 HCWs in the cross-sectional analysis; 294 cases and 294 controls in the case-control analysis.

RESULTS

Twenty-four percent (n=733) of the HCWs had a positive QFT-Plus. The median (interquartile range) age was 34.0 (31.0-37.1) years, 71% were female, and only 24.8% were of Saudi nationals. Nursing represented 57.7% of HCWs, and 24.7% were working in a non-clinical area. Only 20.3% worked in TB-related departments. A higher risk of LTBI was present in HCWs who were older than 50 years (OR=1.95), from either Philippines (OR=4.7) or the Indian subcontinent (OR=4.1), working as a nurse (OR=2.7), allied health profession (OR=2.1), radiology technician (OR=3.1), or in the emergency room (OR=2.4) or intensive care unit (OR=2.1). In the binary logistic regression, independent predictors for positive QFT-Plus were age group older than 50 years (aOR=2.96), known TB exposure (aOR=1.97), and not receiving BCG at birth (aOR=3.08).

LIMITATION

Single-center, retrospective, possible recall bias for BCG vaccination.

CONCLUSION

The high prevalence of LTBI among HCW emphasizes the need to continue pre-employment screening, especially for employed personnel from high endemic areas, with targeted annual screening for the same group and other identified high-risk groups. These findings can aid in the development of national screening guidelines for LTBI in HCW.

CONFLICT OF INTEREST

None.

Incidence of latent tuberculosis infection among health science students during clinical training

BACKGROUND:

The prevalence of latent tuberculosis infection (LTBI) has been found to be high among students undergoing clinical training. The aim of this study is to determine the incidence of LTBI among undergraduate health science students after their clinical training and to compare the risk between different college specialties.

METHODS:

This is a retrospective cohort study of students who completed their clinical training from 2010 to 2017. The risk of LTBI was defined based on the conversion of tuberculin skin test (TST) results from negative at the start of training to positive after the completion of training.

RESULTS:

A total of 2000 students were evaluated, of whom 1997 were included in this analysis. Six percent tested positive in the first TST of the initial screening. Ten percent of students with a normal baseline TST converted to positive on the follow-up TST. Clinical training in the college of medicine increased the risk of LTBI by 76% (odds ratio: 1.76; 95% confidence interval: 1.04– 2.96; P = 0.03) compared to clinical training in other medical colleges.

CONCLUSIONS:

The risk of acquiring LTBI during clinical training in health science colleges is 10%. Students in the college of medicine are at significantly higher risk of LTBI than students of other health science specialties.

The global prevalence of latent tuberculosis: a systematic review and meta-analysis

In 1999, the World Health Organization (WHO) estimated that one-third of the world's population had latent tuberculosis infection (LTBI), which was recently updated to one-fourth. However, this is still based on controversial assumptions in combination with tuberculin skin test (TST) surveys. Interferon-γ release assays (IGRAs) with a higher specificity than TST have since been widely implemented, but never used to estimate the global LTBI prevalence.We conducted a systematic review and meta-analysis of LTBI estimates based on both IGRA and TST results published between 2005 and 2018. Regional and global estimates of LTBI prevalence were calculated. Stratification was performed for low, intermediate and high TB incidence countries and a pooled estimate for each area was calculated using a random effects model.Among 3280 studies screened, we included 88 studies from 36 countries with 41 IGRA (n=67 167) and 67 TST estimates (n=284 644). The global prevalence of LTBI was 24.8% (95% CI 19.7-30.0%) and 21.2% (95% CI 17.9-24.4%), based on IGRA and a 10-mm TST cut-off, respectively. The prevalence estimates correlated well to WHO incidence rates (Rs=0.70, p<0.001).In the first study of the global prevalence of LTBI derived from both IGRA and TST surveys, we found that one-fourth of the world's population is infected. This is of relevance, as both tests, although imperfect, are used to identify individuals eligible for preventive therapy. Enhanced efforts are needed targeting the large pool of latently infected individuals, as this constitutes an enormous source of potential active tuberculosis.

Xpert MTB/RIF assay for the diagnosis of Mycobacterium tuberculosis and Rifampicin resistance in high Human Immunodeficiency Virus setting in Gambella regional state, southwest Ethiopia

Background

The introduction of a new and rapid molecular diagnostic for tuberculosis (TB) and rifampicin resistance (RIF) in the national TB program has improved the diagnosis of TB by shortening the turnaround time and detecting the presence of RIF resistance in high TB and human immunodeficiency virus (HIV) settings such as Ethiopia. However, the implementation of this new diagnostic tool for the diagnosis of M. tuberculosis (MTB) and rifampicin (RIF) resistance in clinical setting is limited known in the country. Hence, this study intended to describe the program of GeneXpert MTB/RIF in the diagnosis of TB and RIF in high HIV setting in Gambella Regional State, Southwest Ethiopia.

Method

Institutional based retrospective study was conducted among presumptive TB patients diagnosed with GeneXpert assay in the last three years (2015–2017) in Gambella Hospital from May 1–30, 2017. The data were collected from GeneXpert registration book using standard data extraction sheet. The data were entered and cleared using EPI data 3.1 and then, exported and analyzed using SPSS version 20.0 statistical software package.

Result

Of the 995 presumptive TB patients who received the GeneXpert test in the last three years, 20.0% (95% CI: 17.4–22.7) of them had proven MTB detection while 4.9% (95% CI: 2.2–8.1) had RIF resistance. The prevalence of RIF resistance was 2.3% and 14.3% among the new and retreated cases respectively. There was also a 35.5% TB/HIV co-infections. The odd of MTB detection was higher among 15–29 [AOR 2.17 (95% CI: 1.25- 3.76)] and 30–44 [AOR 2.35 (95% CI: 1.36–4.07)] year old participants. The figure was however significantly lower among female [AOR 0.64 (95% CI: 0.45–0.91)] and unknown HIV status [AOR 0.38(95% CI: 0.24–0.61)] participants of the study. In addition, the odd of RIF resistance was significantly low among HIV unknown case [AOR 0.14 (95% CI: 0.02–0.96)]. It was also learnt that there was progressively decline of invalid or error Xpert result from 4.7% to 2.0% in the course of the study period (X², 25.54; P = 0.001).

Conclusion

The study confirms the high prevalence of TB, RIF resistance and TB/HIV co-infection among the study participants. Age, sex, and HIV status of the study participants were predictor factors for MTB detection while HIV status was associated with RIF resistance. Therefore, the results of the study indicate that there is the need for collaborative and intensified prevention of TB and HIV in the study area. The ongoing supervision and mentoring to improve the performance of Xpert in the institution need to be promoted.

Prevalence of and risk factors associated with latent tuberculosis in Singapore: A cross-sectional survey

OBJECTIVES

This first cross-sectional survey on latent tuberculosis infection (LTBI) in Singapore was performed by utilizing the QuantiFERON Gold In-tube (QFT-GIT) assay to collect data on the prevalence of LTBI and to identify potential risk factors associated with LTBI.

METHODS

Nationwide household addresses were selected randomly for enumeration, and Singaporeans or Permanent Residents aged 18-79 years were identified. One eligible member per household was selected using the Kish grid. Each participant answered a questionnaire assessing their medical history (including tuberculosis (TB)), socio-economic factors, and lifestyle factors. They also provided a blood specimen for the QFT-GIT assay. Participants with a positive QFT-GIT result were defined as having LTBI if they were asymptomatic. To identify independent risk factors, adjusted hazard ratios were obtained using the multivariable modified Breslow-Cox proportional hazards model.

RESULTS

An overall QFT-GIT positivity rate of 12.7% was detected amongst 1682 Singapore residents. There was a wide variation in the positivity rate according to the participants' country of birth. Higher LTBI prevalence was also significantly associated with increasing age, lower educational and socio-economic status, and alcohol use.

CONCLUSIONS

Given the high prevalence of LTBI amongst foreign-born residents from regional countries, similar studies should be conducted amongst migrants in Singapore to improve national guidelines on screening and preventive treatment against LTBI.