Prevalence Of Active Tuberculosis Research Articles

Effects of the Beijing genotype on latent tuberculosis infection, TB disease risk, and clustering of TB cases

BackgroundThe Beijing genotype of Mycobacterium tuberculosis (Mtb) has sparked debate regarding its virulence and transmissibility. This study contributes to this discussion by assessing its effect on the risk of latent tuberculosis infection (LTBI), active tuberculosis (TB) disease among contacts, and clustering of known TB cases. MethodsWe conducted a retrospective cohort study using the records of 4457 culture-confirmed TB patients and their contacts (20,448) reported to the Florida Department of Health between 2009 and 2023. Univariate and multivariate analyses were used to evaluate the effect of the Beijing strain on LTBI, active TB risk among contacts, and case clustering. ResultsOur study revealed no significant difference in transmissibility between the Beijing and non-Beijing genotypes among contacts. LTBI prevalence was 19.9%, slightly higher in non-Beijing than Beijing genotypes (20.2% vs. 15.5%, p < 0.001). The prevalence of active TB was 1.8%, with no significant difference between the Beijing and non-Beijing genotypes (1.4% vs. 1.8%, p = 0.296). Increased LTBI risk was associated with older age, male sex, Hispanic ethnicity, multidrug-resistant TB exposure, household exposure, and a longer exposure duration. Active TB risk was higher for males, HIV-positive individuals, and contacts with more prolonged exposure to index cases. The Beijing genotype was associated with increased TB case clustering (aOR = 1.98, 95%CI: 1.53, 2.55, p < 0.001) as compared to the non-Beijing genotypes. US birthplace (aOR = 2.75, 95%CI: 2.37, 3.19, p < 0.001), pulmonary disease (aOR = 1.27, 95%CI: 1.04, 1.56, p < 0.020), cavitary TB (aOR = 1.25, 95% CI: 1.08, 1.44, p < 0.003), previous year alcohol use (aOR = 1.68, 95%CI: 1.38, 2.04, p < 0.001), and recreational drug use (aOR = 1.32, 95%CI: 1.04, 1.67, p < 0.024) were also associated with an increased risk of TB case clustering. ConclusionWhile the Beijing genotype did not increase the risk of LTBI or active TB among contacts, it showed a higher tendency for case clustering. Hence, interventions should prioritize populations where this genotype is prevalent.

Prevalence of Tuberculosis among People Who Use Drugs in Iran: A Systematic Review and Meta-analysis.

Drug use, especially injecting drug use, is associated with a higher risk of tuberculosis (TB). This study aimed to systematically review the prevalence of TB among people who use drugs (PWUD) in Iran. A systematic search was conducted in international and national databases. All studies that provided data on the prevalence of TB among PWUD based on screening tests and diagnosis from 1990 up to August 2019 were assessed. Meta-analysis was performed on the prevalence of active TB among people who inject drugs (PWID). Overall, nine studies were included. The studies were carried out from 1994 to 2012 in seven out of the 31 provinces of Iran. Seven studies provided data on the prevalence of TB diagnosis among 1087 PWID. The pooled prevalence of TB diagnosis was 10.1% (95% CI: 4.5, 15.8) in studies carried out in hospitals and 0.54% (95% CI: 0.04, 1.04) in other settings. The present review suggests an approximately 40 times higher prevalence of TB among PWID compared to the general population. However, most of the included studies were conducted on a subpopulation of drug users, and caution should be exercised when generalizing the findings.

Thoracic Inlet in Cervical Spine CT of Blunt Trauma Patients: Prevalence of Pathologies and Importance of CT Interpretation.

The thoracic inlet of blunt trauma patients may have pathologies that can be diagnosed on cervical spine computed tomography (CT) but that are not evident on concurrent portable chest radiography (pCXR). This retrospective investigation aimed to identify the prevalence of thoracic inlet pathologies on cervical spine CT and their importance by measuring the diagnostic performance of pCXR and the predictive factors of such abnormalities. This investigation was performed at a level-1 trauma center and included CT and concurrent pCXR of 385 consecutive adult patients (280 men, mean age of 47.6 years) who presented with suspected cervical spine injury. CT and pCXR findings were independently re-reviewed, and CT was considered the reference standard. Traumatic, significant nontraumatic and nonsignificant pathologies were present at 23.4%, 23.6% and 58.2%, respectively. The most common traumatic diagnoses were pneumothorax (12.7%) and pulmonary contusion (10.4%). The most common significant nontraumatic findings were pulmonary nodules (8.1%), micronodules (6.8%) and septal thickening (4.2%). The prevalence of active tuberculosis was 3.4%. The sensitivity and positive predictive value of pCXR was 56.67% and 49.51% in diagnosing traumatic and 8.89% and 50% in significant nontraumatic pathologies. No demographic or pre-admission clinical factors could predict these abnormalities. Several significant pathologies of the thoracic inlet were visualized on trauma cervical spine CT. Since a concurrent pCXR was not sensitive and no demographic or clinical factors could predict these abnormalities, a liberal use of chest CT is suggested, particularly among those experiencing high-energy trauma with significant injuries of the thoracic inlet. If chest CT is not available, a meticulous evaluation of the thoracic inlet in the cervical spine CT of blunt trauma patients is important.

Mycobacterium Tuberculosis Infection after Kidney Transplantation: A Comprehensive Review.

Tuberculosis (TB) in kidney transplant (KT) recipients is an important opportunistic infection with higher incidence and prevalence than in the general population and is associated with important morbidity and mortality. We performed an extensive literature review of articles published between 1 January 2000 and 15 June 2022 to provide an evidence-based review of epidemiology, pathogenesis, diagnosis, treatment and outcomes of TB in KT recipients. We included all studies which reported epidemiological and/or outcome data regarding active TB in KT, and we approached the diagnostic and treatment challenges according to the current guidelines. Prevalence of active TB in KT recipients ranges between 0.3–15.2%. KT recipients with active TB could have a rejection rate up to 55.6%, a rate of graft loss that varies from 2.2% to 66.6% and a mortality rate up to 60%. Understanding the epidemiological risk, risk factors, transmission modalities, diagnosis and treatment challenges is critical for clinicians in providing an appropriate management for KT with TB. Among diagnostic challenges, which are at the same time associated with delay in management, the following should be considered: atypical clinical presentation, association with co-infections, decreased predictive values of screening tests, diverse radiological aspects and particular diagnostic methods. Regarding treatment challenges in KT recipients with TB, drug interactions, drug toxicities and therapeutical adherence must be considered.

Prevalence of active tuberculosis and associated factors among people with chronic psychotic disorders at St. Amanuel Mental Specialized Hospital and Gergesenon Mental Rehabilitation center, Addis Ababa, Ethiopia

BackgroundTuberculosis (TB) is an airborne chronic infectious disease mainly caused by Mycobacterium tuberculosis complex bacteria. Currently, about 1.7 billion (26%) of the world’s population are considered to be infected with M. tuberculosis. The risk of acquiring tuberculosis is higher on some segments of societies including people with severe mental illness. As a result, World health organization (WHO) strongly recommends screening for tuberculosis in such risk groups and setting.MethodsA cross-sectional study was conducted to assess the prevalence of active tuberculosis and associated factors among patients with chronic psychotic disorders admitted at St. Amanuel Mental Specialized Hospital and Gergesenon Mental rehabilitation center from February to June, 2020. All admitted patients were screened for any sign of TB as recommended by WHO. Presumptive TB cases were identified. Sputum samples were collected and tested by Xpert MTB/RIF assay. Data analysis was performed using SPSS version 25.0 statistical software and Chi square analysis was used to test the statistical association.ResultsFrom a total 3600 pschotic patients screened for TB, 250 (6.94%) presumptive tuberculosis cases were detected. From these, 27 (10.8%) were positive by Xpert MTB/RIF assay. Most of the patients were males (68.4%). The mean ± SD age of the participant was 36.5 ± 9.7 years. The overall prevalence of tuberculosis was found to be 750 per 100,000 population. The number of patients per room (p = 0.039) was associated with Xpert MTB/RIF positive active tuberculosis.ConclusionThe prevalence of active tuberculosis among chronic psychotic patients was high. Number of admitted patients per room was identified as risk factors for Xpert MTB/RIF positive active tuberculosis. Therefore, to control TB transmission in chronic mental health treatment facilities, efforts should be directed to periodic screening for early case detection and improving the number of patients per room.

Active case-finding of tuberculosis in general populations and at-risk groups: a systematic review and meta-analysis.

The World Health Organization (WHO) recommends active case-finding (ACF) of tuberculosis (TB) in certain high-risk groups; however, more evidence is needed to elucidate the scope of ACF beyond the current recommendations. In this study we aimed to systematically review yields (the prevalence of active TB) of studies on ACF in general populations and at-risk groups. A literature search in PubMed, Embase and the Cochrane Central Library (CENTRAL) was performed for studies concluded after 31 December 1999 and published before 1 September 2020. Screening yields were estimated and yield/prevalence ratios (ratio between yield of study and WHO estimated prevalence of TB) were calculated to assess which groups might especially benefit from ACF. Finally, risk of bias was assessed and heterogeneity was investigated using meta-regression and sensitivity analyses. We included 197 studies, with a total of 12 372 530 screened and 53 158 cases found. Yields were high among drug users, close contacts, the poor and marginalised, people living with HIV, and prison inmates across incidence strata, and estimated yield/prevalence ratios in screenings of general populations tended to be >1 with an overall ratio of 1.4 and ranging between 1.0 and 1.5. Sensitivity analyses suggested that inclusion of studies at high risk of bias contributed to underestimation of yields. Despite many studies using insensitive screening methods, these results suggest that more at-risk groups should be considered for inclusion in future screening recommendations and that screening of general populations may outperform current case-finding practices, providing evidence for extending ACF beyond the current recommendations.

Tuberculosis in persons with sudden unexpected death, in Cape Town, South Africa

BackgroundGlobally, tuberculosis (TB) remains one of the leading causes of death from a single infectious agent, but there has been little work to estimate mortality before the diagnosis of TB. We investigated the burden of diagnosed and undiagnosed TB in adult and child sudden unexpected deaths (SUDs) evaluated at Tygerberg Forensic Pathology Services, South Africa. MethodsIn a retrospective descriptive study spanning 2016, we identified all SUDs where active TB was detected at post-mortem and matched with routine health service data to differentiate decedents who were diagnosed or undiagnosed with TB before death. A patient pathway analysis of the health service activities preceding SUD in adults with active TB was conducted. ResultsActive TB was identified at post-mortem in 6.2% (48/770) of SUDs and was undiagnosed before death in 91.7% (44/48). The prevalence of active TB was 8.1% in adult SUDs (90.1% undiagnosed before SUD) and 1.8% in children (none diagnosed before SUD). Patient pathway analysis was possible for 15 adult SUDs, and this documented primary health care clinic attendances and hospital admissions in the six months preceding death and missed opportunities for TB investigations. ConclusionThe prevalence of TB among SUDs in the Eastern Metro of Cape Town is high. Most active TB at post-mortem was undiagnosed before death, and multiple missed opportunities for TB investigation and diagnosis were noted. The systematic evaluation of all SUDs for TB could improve the reporting of undiagnosed TB and support risk mitigation for healthcare workers involved with the post-mortem process.

Impact of the interferon-γ release assay and glomerular filtration rate on the estimation of active tuberculosis risk before bronchoscopic examinations: a retrospective pilot study.

BackgroundBronchoscopic examinations are vital to diagnose pulmonary diseases. However, as coughing is triggered during and after the procedure, it is imperative to take measures against nosocomial infections, especially for airborne infections like tuberculosis (TB). The interferon-γ release assay (IGRA) has recently been established as a method to evaluate the infection status of TB. We aimed to ascertain the efficacy of IGRA and clinical findings in estimating the prevalence of active TB before bronchoscopy.MethodsWe obtained IGRA results from 136 inpatients using a QuantiFERON-TB Gold In-Tube test. Bronchoscopy samples were cultured in Mycobacteria Growth indicator tubes and 2% Ogawa solid medium. We evaluated the adjusted effects of multiple clinical variables on active TB status using a logistic regression model. In addition, multiple variables were converted into a decision tree to predict active TB.ResultsFive (3.7%) patients were diagnosed with culture-positive TB, two of whom were simultaneously diagnosed with non-small-cell lung carcinoma or small-cell lung carcinoma. The multivariate analysis suggested the probability of predicting active TB using the IGRA [odds ratio (OR), 72.7; 95% confidence interval (CI), 3.169–1668; P=0.007] and decreased estimated glomerular filtration rate (eGFR) (OR, 0.937; 95% CI, 0.882–0.996; P=0.038) in patients undergoing bronchoscopy. A decision tree validated the use of these two variables to predict active TB.ConclusionsIGRA test results are useful for predicting active TB before bronchoscopy. This strategy could identify patients who require antibiotic therapy to prevent TB or who are in the active phase of TB.

Prevalence of Tuberculosis among bedside contacts of Smear Positive Tuberculosis Patients at The University Teaching Hospital, Lusaka, Zambia

Background: Screening of contacts of tuberculosis (TB) patients is not routinely done in resourcelimited countries like Zambia despite the World Health Organization (WHO) recommendations, leading to missed opportunities for prevention, early diagnosis and high mortality.Objective: Main objective was to establish the prevalence of latent and active tuberculosis in bedside contacts of smear-positive index patients and associated risk factors.Methods: The study was carried at the University Teaching Hospital, a tertiary level facility. We conducted a cross sectional analytical study. We included 64 TB-unexposed and 69 TB-exposed contacts in this analysis. We recruited bedside contacts of smear-positive TB patients (TB Exposed group) in medical wards and contacts of surgical patients (TB Unexposed group) as a comparison group. A structured questionnaire was used to collect data on demographic, laboratory and clinical parameters among them being, age, gender, residence, relationship index patient's sputum grades BMI and HIV status. Active TB was diagnosed microbiologically and radiologically, while latent tuberculosis infection (LTBI) by tuberculin skin test (TST). Collected data was analysed using STATA 13 to determine the prevalence of TB and LTBI and the associated factors. A p value of &lt; 0.05 was considered statistically significant.Results: The mean age for TB unexposed and that of TB exposed was of 41.2 [±13.5] years and 40.2 [±14.7] years respectively. The Prevalence of active TB in TB exposed and in TB unexposed was 13.0% and 0% respectively. The prevalence of LTBI among TB exposed and TB unexposed was 83.1% and 38.3% respectively. Active TB in TB exposed bedside contact was associated with duration of hospital stay (AOR 2.45, 95% CI 1.0 – 5.9, p = 0.03) and index patient's sputum grade of 2+ (AOR 4.4, 95% CI 1.07 -18.3, p = 0.04).Conclusion: Bedside contacts of active TB patients are at an increased risk of contracting both latent and active TB. Further, our findings suggest a significant prevalence of LTBI in the general population of Lusaka. Bedside contact tracing is an effective approach to finding the missing TB patients our setting of a high TB burden country/community. The findings call for an urgent need to institute effective TB control/preventive measures with active case finding as a priority and LTBI screening finding and treatment.

HIV prevalence and TB in migrant miners communities of origin in Gaza Province, Mozambique: The need for increasing awareness and knowledge.

BackgroundAs part of ongoing efforts to generate evidence needed on HIV and tuberculosis (TB) to inform policies and programs aimed to improve the health outcomes of migrants and communities affected by migration and mining, a preliminary investigation was conducted through a biological and behavioral (BBS) approach related to HIV and TB in two communities of origin of migrant mineworkers in Gaza Province. The main objective was to determine the prevalence of HIV and the rates of asymptomatic infection by TB, and the social and behavioral risk factors associated.MethodsA cross-sectional survey was conducted from May to June 2017 using a simple random sampling methodology. Eligible participants were individuals who were living in the community at the time the survey was conducted, which included adult mine workers and members of their families aged 18 and above. A socio-behavioral questionnaire was administered, blood specimens were collected for HIV testing (Determine/Unigold) and sputum for TB (GeneXpert MTB/RIF) was collected. The statistical analysis was performed using the R studio software to produce means, proportion and odds ratio at 95% confidence intervals.ResultsA total of 1012 participants were enrolled, 75.2% were females, with a median age of 34. The overall prevalence of HIV found in the two communities was 24.2% (CI: 21.6–27.0) and was higher in the rural community (31.6%; 95% CI: 27.0–35.3). The prevalence of active TB was found to be 0.3% (n = 3) while 7.5% of the participants self-reported to have been previously diagnosed with TB at some point in their life. Only 2.8% of participants had knowledge of the basic principles of TB transmission. Condom use at last sexual intercourse with a regular partner was low among both sexes (17.3% male and 12.6% female). A considerable proportion of participants had not been aware of their HIV positive serostatus(31.1% female and 25.0% male). About 1/3 of the participants had had a history of STIs.ConclusionThe results of this survey confirm a high prevalence of HIV in communities of origin of migrant miners in Gaza province. Findings also demonstrated low levels of awareness/ knowledge and prevention of TB and HIV. It is important to strengthen strategies that encourage regular HIV testing and TB screening. Appropriate communication interventions on methods of transmission and prevention of HIV and TB in these communities must be intensified, as well as ensuring ongoing linkage to TB and HIV social and healthcare services.

Factors associated with tuberculosis disease among children who are household contacts of tuberculosis cases in an urban setting in Malaysia

BackgroundWith the rise in prevalence of childhood tuberculosis (TB) globally, contact tracing should be a powerful strategy for early diagnosis and management, especially in children who are household contacts of active TB cases. Here, we aimed to determine the prevalence and factors associated with TB disease in children who are household contacts of TB cases.MethodsWe used a cross-sectional study with data from the Malaysian TB Information System (TBIS) recorded from 1 January 2014 to 31 December 2017. All children aged 0–14 years who were registered in the TBIS with at least one household contact of TB cases were included in the study. Multiple logistic regression analysis was performed to calculate the adjusted odds ratio (adj. OR) and for adjusting the confounding factors.ResultsA total of 2793 children were included in the study. The prevalence of active TB was 1.5% (95% confidence interval [CI]: 1.31, 1.77%). Children aged < 5 years [adj. OR 9.48 (95% CI: 3.41, 26.36) p < 0.001] with positive tuberculin skin test [adj. OR 395.73 (95% CI: 134.17, 1167.13), p < 0.001] and investigation period of > 6 weeks [adj. OR 7.48 (95% CI: 2.88, 19.43), p < 0.001] had significantly higher odds for TB disease.ConclusionsThe prevalence of TB disease in children who were household contacts of TB cases is relatively low. However, contact tracing programmes should not only focus on children aged < 5 years and with positive tuberculin skin test results, but also be empowered to reduce the investigation period.

The Proportion of Latent Tuberculosis Infection in Naive Lung Cancer Patients at Persahabatan Hospital Jakarta

Background: Lung cancer and pulmonary tuberculosis (TB) are two major public health problems associated with significant morbidities and mortalities. The increased prevalence of active TB and latent TB reactivation in lung cancer patients and negative effect of pulmonary TB in lung cancer prognosis needed screening of lung cancer patients for latent TB infection (LTBI). This study aimed to determine the proportion of LTBI in lung cancer patients, their characteristics and the relationship between them.&#x0D; Methods: This study used cross-sectional design. Collecting sample used consecutive sampling of 86 newly diagnosed treatment-naive lung cancer patients from RSUP Persahabatan in 2015 to 2016. The presence of LTBI was determined by Quantiferon-TB Gold-In-Tube (QFT- GIT) after having Mycobacterium TB not detected result from Xpert MTB/RIF sputum test. Demographic characteristics and cancer-related factors associated with LTBI were investigated.&#x0D; Results: The results of latent TB tests were IGRA(+) 12.8%, IGRA(-) 68.6% and IGRA(I) 18.6%. Number of male patients with lung cancer with latent were 68.6%, as many as 55.8% were immunized with BCG, 4.6% had close contact with TB and 64% were using smoking. Most types of cancer were adenocarcinomas (77.9%) with advanced stage (82.6%) and general display status 2 (50%). The characteristics that show an association with IGRA results are the location of the cancer and the total lymphocyte count.&#x0D; Conclusion: The proportion of latent TB in lung cancer patients at the RSUP Persahabatan was 12.8%. The location of the cancer associated with the area of typical TB was related to latent TB, although it cannot be canceled. Results of IGRA(I) in lung cancer patients with low total lymphocyte counts prove IGRA sensitivity in the protection of latent TB infection in immunocompromised patients. (J Respir Indo. 2019; 39(4): 256-65)

Epidemic Situation of Tuberculosis in Prisons in the Central Region of China.

We aimed to investigate the epidemic situation of tuberculosis (TB) in prisons in the central region of China. Tuberculosis screening was carried out in two prisons in middle China. A sum of 3,459 prisoners accepted chest X-ray examination; 40 of them were diagnosed as active TB patients. The active TB prevalence (1,156/105) was significantly higher than that of the province and China's general population (P < 0.01). As for gender, TB prevalence in men's prison (1,589/105) was higher than that in the women's prison (946/105). Nevertheless, the risk of having TB in women's prison was much higher than that in the men's prison when compared with the TB prevalence from the province (women: OR = 2.37, 95% CI: 1.34, 4.22; men: OR = 1.53, 95% CI: 0.90, 2.60) and the China's general population (women: OR = 3.30, 95% CI: 2.15, 5.09; men: OR = 2.06, 95% CI: 1.29, 3.30). In view of the severe epidemic situation of TB in prisons, integrating medical resources to establish a consummate and effective management system is necessary.

Resolving outbreak dynamics using approximate Bayesian computation for stochastic birth-death models.

Earlier research has suggested that approximate Bayesian computation (ABC) makes it possible to fit simulator-based intractable birth-death models to investigate communicable disease outbreak dynamics with accuracy comparable to that of exact Bayesian methods. However, recent findings have indicated that key parameters, such as the reproductive number R, may remain poorly identifiable with these models. Here we show that this identifiability issue can be resolved by taking into account disease-specific characteristics of the transmission process in closer detail. Using tuberculosis (TB) in the San Francisco Bay area as a case study, we consider a model that generates genotype data from a mixture of three stochastic processes, each with its own distinct dynamics and clear epidemiological interpretation. We show that our model allows for accurate posterior inferences about outbreak dynamics from aggregated annual case data with genotype information. As a byproduct of the inference, the model provides an estimate of the infectious population size at the time the data werecollected. The acquired estimate is approximately two orders of magnitude smaller than assumed in earlier related studies, and it is much better aligned with epidemiological knowledge about active TB prevalence. Similarly, the reproductive number Rrelated to the primary underlying transmission process is estimated to be nearly three times larger than previous estimates, which has a substantial impact on the interpretation of the fitted outbreak model.

Interaction of nutritional status and diabetes on active and latent tuberculosis: a cross-sectional analysis

BackgroundMalnutrition and diabetes are risk factors for active tuberculosis (TB), possible risk factors for latent TB infection (LTBI), and may interact to alter their effect on these outcomes. Studies to date have not investigated this interaction.MethodsWe enrolled 919 newly diagnosed active TB patients and 1113 household contacts at Primary Health Centres in Puducherry and Tamil Nadu, India from 2014 to 2018. In cross-sectional analyses, we used generalized estimating equations to measure additive and multiplicative interaction of body mass index (BMI) and diabetes on two outcomes, active TB and LTBI.ResultsAmong overweight or obese adults, active TB prevalence was 12-times higher in diabetic compared to non-diabetic participants, 2.5-times higher among normal weight adults, and no different among underweight adults (P for interaction < 0.0001). Diabetes was associated with 50 additional active TB cases per 100 overweight or obese participants, 56 per 100 normal weight participants, and 17 per 100 underweight participants (P for interaction < 0.0001). Across BMI categories, screening 2.3–3.8 active TB patients yielded one hyperglycemic patient. LTBI prevalence did not differ by diabetes and BMI*diabetes interaction was not significant.ConclusionsBMI and diabetes are associated with newly diagnosed active TB, but not LTBI. Diabetes conferred the greatest risk of active TB in overweight and obese adults whereas the burden of active TB associated with diabetes was similar for normal and overweight or obese adults. Hyperglycemia was common among all active TB patients. These findings highlight the importance of bi-directional diabetes-active TB screening in India.

Active and latent tuberculosis among inmates in La Esperanza prison in Guaduas, Colombia.

IntroductionActive tuberculosis (TB) and latent tuberculosis infection (LTBI) are a public health threat in prisons around the world. The objectives of the study were to estimate the prevalence of LTBI and TB as well as to investigate TB transmission inside one prison, in Colombia.MethodsA Cross-sectional study was conducted in inmates who agreed to participate. Inmates with respiratory symptoms (RS) of any duration underwent to medical evaluation and three sputum samples were taken for smear microscopy and culture for TB diagnosis. Drug susceptibility was analyzed using BACTEC MGIT 960 and GenoType MTBDRplus. Molecular genotyping of Mycobacterium tuberculosis isolates was performed by 24-Locus MIRU-VNTR and spoligotyping. LTBI was evaluated according to the result of the tuberculin skin test (TST). Close contact investigation was conducted inside the prison for inmates that shared the cell with the index TB case.ResultsAmong 301/2,020 (15%) inmates with RS of any duration, 8% were diagnosed with active TB. The prevalence of active TB was 1,026 cases/100,000 inmates. We isolated M. tuberculosis in 19/24 (79%) TB cases, 94.7% were susceptible to first line drugs and only one was monoresistant to isoniazid. The most prevalent sub-lineage was Haarlem (68.4%), followed by LAM (26.3%) and T superfamily (5.3%). 24-Locus MIRU-VNTR typing results alone or in combination with spoligotyping identified three clusters containing two isolates each. Two clusters corresponded to inmates that shared the same cell, but each one was located in different blocks of the prison. Inmates from the last cluster were in the same block in nearby cells. TST reading was performed in 95.6% inmates, and 67.6% had a positive reaction.ConclusionsThe prevalence of LTBI and TB was higher in prison than in the general population. Molecular genotyping suggests that TB in this prison is mainly caused by strains imported by inmates or endogenous reactivation.

Resolving outbreak dynamics using approximate Bayesian computation for stochastic birth-death models

Earlier research has suggested that approximate Bayesian computation (ABC) makes it possible to fit simulator-based intractable birth-death models to investigate communicable disease outbreak dynamics with accuracy comparable to that of exact Bayesian methods. However, recent findings have indicated that key parameters such as the reproductive number R may remain poorly identifiable with these models. Here we show that the identifiability issue can be resolved by taking into account disease-specific characteristics of the transmission process in closer detail. Using tuberculosis (TB) in the San Francisco Bay area as a case-study, we consider a model that generates genotype data from a mixture of three stochastic processes, each with their distinct dynamics and clear epidemiological interpretation. We show that our model allows for accurate posterior inferences about outbreak dynamics from aggregated annual case data with genotype information. As a by-product of the inference, the model provides an estimate of the infectious population size at the time the data was collected. The acquired estimate is approximately two orders of magnitude smaller compared to the assumptions made in the earlier related studies, and much better aligned with epidemiological knowledge about active TB prevalence. Similarly, the reproductive number R related to the primary underlying transmission process is estimated to be nearly three-fold compared with the previous estimates, which has a substantial impact on the interpretation of the fitted outbreak model.

Spatial and temporal projections of the prevalence of active tuberculosis in Cambodia

IntroductionCambodia is among the 30 highest burden of tuberculosis (TB) countries. Active TB prevalence has been estimated using nationally representative multistage sampling that represents urban, rural and remote parts of...

A population-based tuberculosis contact investigation in the country of Georgia

Setting: Identification and screening of contacts of patients with active tuberculosis (TB) is infrequent in low- and middle-income countries. Objective: To estimate the incidence, prevalence and risk factors of latent tuberculous infection (LTBI) and active TB among contacts of newly reported smear-positive TB patients. Design: A population-based contact investigation of sputum smear-positive pulmonary TB (PTB) cases diagnosed between April and December 2012 in Georgia was conducted. LTBI was assessed using the tuberculin skin test (TST). Contacts with active TB were identified from the National TB Program surveillance database. Results: Among 896 index patients with active TB, 3133 contacts were identified and 1157 (37%) underwent a TST, 34% of whom were positive. Most contacts were household contacts (86%) and female (58%). Among contacts, the 1-year period prevalence of active TB was 3.3% (95%CI 2.70-3.98); the incidence rate was 1101 per 100 000 person-years (95%CI 822-1443). In multivariable analysis, household contacts were more likely to have LTBI (adjusted OR [aOR] 2.28, 95%CI 1.49-3.49) than close contacts. Conclusions: A high prevalence of both LTBI and active TB was identified among contacts of PTB cases. Efforts aimed at active case finding among TB contacts should improve early case detection and enhance TB control efforts.

Low Prevalence of Active Tuberculosis among High-Risk Pregnant and Postpartum Women in Sweden: A Retrospective Epidemiological Cohort Study Using and Evaluating TST as Screening Method

Objective Studies on the prevalence of active tuberculosis (TB) and latent tuberculosis infection (LTBI) among high-risk pregnant and postpartum women are few and prevalence is not well known. The methods used for diagnosing and treating TB and LTBI also differ both within and between countries. The aim of the study was to investigate the prevalence of TB and LTBI among high-risk pregnant and postpartum women in a Western Region of Sweden using tuberculin skin test (TST) as screening method. Secondary aims were to evaluate the effectiveness of the screening method and possible negative labour and neonatal outcomes among TST-positive women. Methods Pregnant women attending an antenatal care unit (ACU) allocated for TST screening were investigated and followed up for two years postpartum. Results Only one woman out of 902 screened women in the study group was diagnosed with active TB because of TB symptoms and not because of positive TST. 36% of the skin-tested women fulfilled criteria for LTBI. No difference in perinatal outcome was found between women with and without positive TST. Conclusions Our findings suggest that TST screening of high-risk women may not be an effective strategy, since the prevalence of active TB is low. Investigating pregnant and postpartum women with TB symptoms instead of TST for screening could be an option in low TB prevalence areas. The criteria for diagnosing and treating LTBI should be clearly stated.