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Tuberculosis is a re-emerging disease causing a growing public health burden. The current study was conducted to investigate the occurrence of Mycobacterium tuberculosis among cattle and buffaloes with tuberculous lesions. Typical tuberculous lesions were collected from 34 cattle and 34 buffaloes (Bubalus bubalis) through postmortem examination of slaughtered animals in abattoirs. DNAs were extracted from samples, and M. tuberculosis was identified by PCR. Positive samples were examined for resistance against rifampicin and isoniazid using GenoType MTBDRplus. Moreover, sera from 90 slaughterhouse workers, butchers, or meat inspectors were examined for the presence of M. tuberculosis antibodies using ELISA. Five cattle (14.7 %) and three buffaloes (8.8 %) tested positive. M. tuberculosis from one cattle was resistant to rifampicin and another was resistant to isoniazid. In addition, the seroprevalence of M. tuberculosis IgG among examined humans was 5.6 %. The occurrence of M. tuberculosis in cattle and buffaloes is a public health concern.

Current migratory movements require new strategies for rapidly tracking the transmission of high-risk imported Mycobacterium tuberculosis strains. Whole-genome sequencing (WGS) enables us to identify single-nucleotide polymorphisms (SNPs) and therefore design PCRs to track specific relevant strains. However, fast implementation of these strategies in the hospital setting is difficult because professionals working in diagnostics, molecular epidemiology, and genomics are generally at separate institutions. In this study, we describe the urgent implementation of a system that integrates genomics and molecular tools in a genuine high-risk epidemiological alert involving 2 independent importations of extensively drug resistant (XDR) and pre-XDR Beijing M. tuberculosis strains from Russia into Spain. Both cases involved commercial sex workers with long-standing tuberculosis (TB). The system was based on strain-specific PCRs tailored from WGS data that were transferred to the local node that was managing the epidemiological alert. The optimized tests were available for prospective implementation in the local node 33 working days after receiving the primary cultures of the XDR strains and were applied to all 42 new incident cases. An interpretable result was obtained in each case (directly from sputum for 27 stain-positive cases) and corresponded to the amplification profiles for strains other than the targeted pre-XDR and XDR strains, which made it possible to prospectively rule out transmission of these high-risk strains at diagnosis., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Background: Studies show obesity decreases risk of tuberculosis (TB) disease. There is limited evidence on whether high body mass index also protects against TB infection; how very high body mass indices influence TB risk; or whether nutritional status predicts this risk in children. We assessed the impact of body mass index on incident TB infection and disease among adults and children., Methods and Findings: We conducted a prospective cohort study among household contacts of pulmonary TB cases in Lima, Peru. We determined body mass index at baseline and followed participants for one year for TB infection and disease. We used Cox proportional regression analyses to estimate hazard ratios for incident TB infection and disease. We enrolled 14,044 household contacts, and among 6853 negative for TB infection and disease at baseline, 1787 (26.1%) became infected. A total of 406 contacts developed secondary TB disease during follow-up. Body mass index did not predict risk of TB infection but overweight household contacts had significantly decreased risk of TB disease (HR 0.48; 95% CI 0.37-0.64; p <0.001) compared to those with normal weight. Among adults, body mass index ≥ 35 kg/m2 continued to predict a lower risk of TB disease (HR 0.30; 95% CI 0.12-0.74; p 0.009). We found no association between high body mass index and TB infection or disease among children under 12 years of age., Conclusions: High body mass index protects adults against TB disease even at levels ≥ 35 kg/m2. This protective effect does not extend to TB infection and is not seen in children., Competing Interests: The authors have declared that no competing interests exist.

Rationale: Policy recommendations on contact investigation of HIV-seropositive patients with tuberculosis have changed several times. Current epidemiologic evidence informing these recommendations is considered low quality, and few large studies investigating the infectiousness of HIV-seropositive and -seronegative index cases have been performed in sub-Saharan Africa., Objectives: We assessed the infectiousness of HIV-seropositive and -seronegative patients with tuberculosis to their household contacts and examined potential modifiers of this relationship., Methods: Adults suffering from their first episode of pulmonary tuberculosis were identified in Kampala, Uganda. Field workers visited index households and enrolled consenting household contacts. Latent tuberculosis infection was measured through tuberculin skin testing, and relative risks were calculated using modified Poisson regression models. Standard assessments of interaction between latent tuberculosis infection, the HIV serostatus of index cases, and other variables were performed., Measurements and Main Results: Latent tuberculosis infection was found in 577 of 878 (65.7%) and 717 of 974 (73.6%) household contacts of HIV-seropositive and -seronegative tuberculosis cases (relative risk, 0.89; 95% confidence interval, 0.82-0.97). On further stratification, cavitary lung disease (P < 0.0001 for interaction) and smear status (P = 0.02 for interaction) of tuberculosis cases modified the infectiousness of HIV-seropositive indexes. Cough duration of index cases did not display interaction (P = 0.499 for interaction)., Conclusions: This study suggests that HIV-seropositive tuberculosis cases may be less infectious than HIV-seronegative patients only when they are smear-negative or lack cavitary lung disease. These results may explain heterogeneity between prior studies and provide evidence suggesting that tuberculosis contact investigation should include HIV-seropositive index cases in high disease burden settings.

The risk of communicable disease transmission during air travel is of public health concern and has received much attention over the years. We retrospectively reviewed information from nine flights (≥ 8 hours) associated with infectious tuberculosis (TB) cases in Ireland between September 2011 and November 2014 to investigate whether possible transmission had occurred. Twenty-four flights notified in Ireland associated with sputum smear-positive pulmonary TB cases with a history of air travel were reviewed. Nine were suitable for inclusion and analysed. Six cases of infectious TB travelled on nine flights. A total of 232 passengers were identified for contact tracing; 85.3% (n = 198) had sufficient information available for follow-up. In total, 12.1% (n = 24) were reported as screened for TB. The results revealed no active TB cases among passengers and 16.7% (n = 4) were diagnosed with latent TB infection (LTBI) all of whom had other risk factors. Despite the limited sample size, we found no evidence of M. tuberculosis transmission from infectious passengers. This study identified challenges in obtaining complete timely airline manifests, leading to inadequate passenger information for follow-up. Receipt of TB screening results from international colleagues was also problematic. The challenge of interpreting the tuberculin skin test results in determining recent vs earlier infection was encountered., Competing Interests: Conflicts of Interest: None declared., (This article is copyright of The Authors, 2016.)

Background: A large isoniazid-resistant tuberculosis outbreak centred on London, United Kingdom, has been ongoing since 1995. The aim of this study was to investigate the power and value of whole genome sequencing (WGS) to resolve the transmission network compared to current molecular strain typing approaches, including analysis of intra-host diversity within a specimen, across body sites, and over time, with identification of genetic factors underlying the epidemiological success of this cluster., Methods and Findings: We sequenced 344 outbreak isolates from individual patients collected over 14 y (2 February 1998-22 June 2012). This demonstrated that 96 (27.9%) were indistinguishable, and only one differed from this major clone by more than five single nucleotide polymorphisms (SNPs). The maximum number of SNPs between any pair of isolates was nine SNPs, and the modal distance between isolates was two SNPs. WGS was able to reveal the direction of transmission of tuberculosis in 16 cases within the outbreak (4.7%), including within a multidrug-resistant cluster that carried a rare rpoB mutation associated with rifampicin resistance. Eleven longitudinal pairs of patient pulmonary isolates collected up to 48 mo apart differed from each other by between zero and four SNPs. Extrapulmonary dissemination resulted in acquisition of a SNP in two of five cases. WGS analysis of 27 individual colonies cultured from a single patient specimen revealed ten loci differed amongst them, with a maximum distance between any pair of six SNPs. A limitation of this study, as in previous studies, is that indels and SNPs in repetitive regions were not assessed due to the difficulty in reliably determining this variation., Conclusions: Our study suggests that (1) certain paradigms need to be revised, such as the 12 SNP distance as the gold standard upper threshold to identify plausible transmissions; (2) WGS technology is helpful to rule out the possibility of direct transmission when isolates are separated by a substantial number of SNPs; (3) the concept of a transmission chain or network may not be useful in institutional or household settings; (4) the practice of isolating single colonies prior to sequencing is likely to lead to an overestimation of the number of SNPs between cases resulting from direct transmission; and (5) despite appreciable genomic diversity within a host, transmission of tuberculosis rarely results in minority variants becoming dominant. Thus, whilst WGS provided some increased resolution over variable number tandem repeat (VNTR)-based clustering, it was insufficient for inferring transmission in the majority of cases., Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: JP has received funding for conference travel and accommodation from Illumina Inc.

In East Greenland, a dramatic increase of tuberculosis (TB) incidence has been observed in recent years. Classical genotyping suggests a genetically similar Mycobacterium tuberculosis (Mtb) strain population as cause, however, precise transmission patterns are unclear. We performed whole genome sequencing (WGS) of Mtb isolates from 98% of culture-positive TB cases through 21 years (n = 182) which revealed four genomic clusters of the Euro-American lineage (mainly sub-lineage 4.8 (n = 134)). The time to the most recent common ancestor of lineage 4.8 strains was found to be 100 years. This sub-lineage further diversified in the 1970s, and massively expanded in the 1990s, a period of lowered TB awareness in Greenland. Despite the low genetic strain diversity, WGS data revealed several recent short-term transmission events in line with the increasing incidence in the region. Thus, the isolated setting and the uniformity of circulating Mtb strains indicated that the majority of East Greenlandic TB cases originated from one or few strains introduced within the last century. Thereby, the study shows the consequences of even short interruptions in TB control efforts in previously TB high incidence areas and demonstrates the potential role of WGS in detecting ongoing micro epidemics, thus guiding public health efforts in the future.

We describe an outbreak of tuberculosis (TB) in the food preparation area of a hospital, which demonstrates that employees in healthcare settings may serve as potential risks for spread of TB even if they have no direct patient contact. Infect Control Hosp Epidemiol 2016;37:1111-1113.

Cell wall components are major determinants of virulence of Mycobacterium tuberculosis and they contribute to the induction of both humoral and cell-mediated immune response. The mammalian cell entry protein 1A (Mce1A), in the cell wall of M. tuberculosis, mediates entry of the pathogen into mammalian cells. Here, we examined serum immunoglobulin levels (IgA, IgM and total IgG) against Mce1A as a potential biomarker for diagnosis and monitoring tuberculosis (TB) treatment response. Serum samples of 39 pulmonary TB patients and 65 controls (15 healthy household contacts, 19 latently infected household contacts, 13 non-TB and 18 leprosy patients) were screened by ELISA. The median levels of all immunoglobulin classes were significantly higher in TB patients when compared with control groups. The positive test results for IgA, IgM and total IgG were 62, 54 and 82%, respectively. For comparison, routine sputum smear examination diagnosed only 26 (67%) of 39 TB cases. Sensitivities of IgA, IgM and IgG test were 59, 51.3 and 79.5%, respectively, while the specificities observed were 77.3, 83.3 and 84.4%, respectively. A significant decrease compared with baseline was also shown after TB treatment. These results suggest that circulating total IgG antibody to Mce1A could be a complementary tool to diagnosis pulmonary TB., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Tuberculosis (TB) remains one of the globe's deadliest communicable diseases. The homeless individuals are at high risk to acquire TB and multi-drug resistant TB (MDR-TB), because of their poor living conditions and risky behaviors. Tuberculosis and MDR-TB in the homeless individuals can pose a risk to entire communities. However, the magnitude of the problem is not known in Ethiopia. Therefore, the aim of this study was to determine the prevalence and associated factors of smear positive pulmonary TB (PTB) and MDR-TB among homeless individuals in Dessie and Debre Birhan towns, Northeast Ethiopia., Methods: A community based cross-sectional study design was conducted from September 2014 to June 2015. Using an active screening with cough of ≥2 weeks, 351 TB suspects homeless individuals were participated in this study. Data were collected by using pre-tested and structured questionnaire. Spot-morning-spot sputum sample was collected and examined for acid-fast bacilli (AFB) using fluorescence microscopy by Auramine O staining technique. All AFB positive sputum was further analyzed by GeneXpert for detection of Mycobacterium tuberculosis complex and rifampicin resistant gene. Univariate and multivariate logistic regressions were applied to identify factors associated with smear positive PTB and P value <0.05 was considered as statistically significant., Results: The prevalence of smear positive PTB was 2.6 % (95 % CI 1.3-5) among TB suspect homeless individuals. Extrapolation of this study finding implies that there were 505 smear positive PTB per 100,000 homeless individuals. All smear positive PTB sputum specimens were further analyzed by GeneXpert assay, the assay confirmed that all were positive for MTBC but none were resistant to RIF or MDR. Smoking cigarette regularly for greater than 5 years (AOR 10.1, 95 % CI 1.1, 97.7), body mass index lower than 18.5 (AOR 6.9, 95 % CI 1.12, 41.1) and HIV infection (AOR 6.8, 95 % CI 1.1, 40.1) were significantly associated with smear positive PTB., Conclusion: The prevalence of smear positive PTB among TB suspect homeless individuals was 2.6 %. Among smear positive PTB, prevalence of HIV co-infection was very high 5 (55.5 %). Smoking cigarette regularly for greater than 5 years, BMI lower than 18.5 and HIV infection were factors associated with smear positive PTB. Special emphasis is needed for homeless individuals to exert intensive effort to identify undetected TB cases to limit the circulation of the disease into the community.

Objective: To determine the yield and determinants of retrospective TB contact investigation in selected zones in Ethiopia., Materials and Methods: This was a community-based cross-sectional study conducted during June-October 2014.Trained lay providers performed symptom screening for close contacts of index cases with all types of TB registered for anti-TB treatment within the last three years. We used logistic regression to determine factors associated with TB diagnosis among the contacts., Results: Of 272,441 close contacts of 47, 021 index cases screened, 13,886 and 2, 091 had presumptive and active TB respectively. The yield of active TB was thus 768/100, 000, contributing 25.4% of the 7,954 TB cases reported from the study zones over the study period. The yield was highest among workplace contacts (12,650/100, 000). Active TB was twice more likely among contacts whose index cases had been registered for TB treatment within the last 12 months compared with those who had been registered 24 or more months earlier (adjusted odds ratio, AOR: 1.77 95% CI 1.42-2.21). Sex or clinical type of TB in index cases was not associated with the yield. Smear negative (SS-) index cases (AOR: 1.74 955 CI 1.13-2.68), having index cases who registered for treatment within <12 months (AOR: 2.41 95% CI 1.51-3.84) and being household contact (AOR: 0.072 95% CI 0.01-0.52) were associated with the occurrence of active TB in children., Conclusions: The yield of retrospective contact investigation was about six times the case notification in the study zones, contributing a fourth of all TB cases notified over the same period. The yield was highest among workplace contacts and in those with recent past history of contact. Retrospective contact screening can serve as additional strategy to identify high risk groups not addressed through currently recommended screening approaches.

Objective: To evaluate the association between age and incident tuberculosis (TB) among human immunodeficiency virus (HIV) infected patients receiving antiretroviral treatment (ART) in South Africa., Design: Prospective cohort analysis among HIV-infected patients initiating ART between April 2004 and April 2012. Generalized estimating equations (GEE) were used with modified Poisson regression clustered by treatment site as a function of sex, age, nucleoside reverse transcriptase inhibitor, CD4 count, hemoglobin levels and year of ART initiation. Cumulative incidence functions stratified by age and controlling for death as a competing risk were used to graphically display incident TB., Results: Although non-significant, GEE models showed that patients aged <1 year had a 40% increase in risk of TB compared to those aged 30-39.9 years. Results also showed that male patients, those with low CD4, those with low hemoglobin and those who initiated ART before 2010 were at increased risk of TB., Conclusions: Our results show that patients aged <1 year, males, patients with low CD4 and those with low hemoglobin at ART initiation are at increased risk of incident TB in the first 24 months of ART. Given the known transmission risk factors for children living in households with a TB contact, reducing TB incidence in HIV-positive adults could substantially impact the risk of TB in young children.

Settings: Two large tuberculosis (TB) centres under a well-functioning National TB Programme (NTP) in Benin, West Africa., Objective: To assess the feasibility and results of integrating a programme of isoniazid preventive therapy (IPT) in children aged <5 years exposed to TB as part of the existing routine activities of the NTP., Method: All children aged <5 years living in the household of a patient with smear-positive pulmonary TB were examined by a doctor and received IPT if no evidence of TB was detected. The children were followed clinically by a nurse for 6 months., Results: From January 2013 to June 2014, 496 children were examined and prescribed IPT among 499 notified contacts; 86% adhered to IPT for at least 6 months. There were six deaths and three cases of active TB among the children, all during the first 3 months of follow-up., Conclusions: In an African country with moderate TB incidence and a well-functioning NTP, the integration of IPT into the NTP for children aged <5 years exposed to TB in the family was feasible based on simple tools associated with the follow-up of index cases. The rate of adherence to IPT was high.

Background: Tuberculosis (TB) can be prevented using isoniazid preventive therapy (IPT) among child contacts. However, the benefits of IPT depend on adherence to at least 6 months of daily treatment. A greater understanding of the barriers to and facilitators of adherence to IPT in resource-poor settings is required to optimise the benefits., Methods: We prospectively evaluated adherence to IPT and its associated factors among child contacts (age 0-5 years) eligible for IPT. We undertook in-depth interviews with care givers and a focus group discussion with health care workers, which were thematically analysed to explore barriers to and facilitators of adherence from the perspective of both care givers and health workers., Results: Of 99 eligible children, 49 (49.5%) did not complete 6 months of IPT. Children whose care giver collected their IPT medications from primary health centres were more likely to have incomplete adherence than those who collected them from hospitals (aOR 2.9, 95%CI 1.1-7.8). Thematic analyses revealed major barriers to and facilitators of adherence: regimen-related, care giver-related and health care-related factors, social support and access. Many of these factors are readily modifiable., Conclusion: Providing information about IPT and improving accessibility for care givers to receive IPT at the primary health care facility should be priorities to facilitate implementation.

Background: Identifying source cases of children exposed to tuberculosis (TB) is challenging. We examined the time-point of obtaining contact information of TB source cases in human immunodeficiency virus (HIV) infected and HIV-exposed uninfected (HEU) children in a randomised, placebo-controlled trial of pre-exposure to isoniazid prophylaxis., Methods: A total of 543 HIV-infected and 808 HEU infants without TB exposure aged 3-4 months were enrolled between 2004 and 2008. At 3-monthly follow-up, infants were evaluated for TB and care givers were asked about new TB exposure., Results: In total, 128 cases of TB disease and 40 deaths were recorded among 19% (105/543) of the HIV-infected and 8% (63/808) of the HEU children; 229 TB contact occasions were reported in 205/1351 (15%) children, of which 83% (189/229) were in the household. Of the 189 household contacts, 108 (53%) underwent microbiological evaluations; 81% (87/108) were positive. HIV-infected and HEU infants had similar frequencies of TB contact: in 48% of infants with definite TB, 58% with probable TB and 43% with possible TB. Of 128 children diagnosed with TB, a TB contact was identified for 59. Of these, 29/59 (49%) were identified at or after the child's TB diagnosis., Conclusion: TB source cases are often identified at or after a child's TB diagnosis. More effort is required for earlier detection., Competing Interests: none

Background: The incidence of TB has doubled in the last 20 years in London. A better understanding of risk groups for recent transmission is required to effectively target interventions. We investigated the molecular epidemiological characteristics of TB cases to estimate the proportion of cases due to recent transmission, and identify predictors for belonging to a cluster., Methods: The study population included all culture-positive TB cases in London residents, notified between January 2010 and December 2012, strain typed using 24-loci multiple interspersed repetitive units-variable number tandem repeats. Multivariable logistic regression analysis was performed to assess the risk factors for clustering using sociodemographic and clinical characteristics of cases and for cluster size based on the characteristics of the first two cases., Results: There were 10 147 cases of which 5728 (57%) were culture confirmed and 4790 isolates (84%) were typed. 2194 (46%) were clustered in 570 clusters, and the estimated proportion attributable to recent transmission was 34%. Clustered cases were more likely to be UK born, have pulmonary TB, a previous diagnosis, a history of substance abuse or alcohol abuse and imprisonment, be of white, Indian, black-African or Caribbean ethnicity. The time between notification of the first two cases was more likely to be <90 days in large clusters., Conclusions: Up to a third of TB cases in London may be due to recent transmission. Resources should be directed to the timely investigation of clusters involving cases with risk factors, particularly those with a short period between the first two cases, to interrupt onward transmission of TB., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Information on geographical variation in localised transmission of TB can inform targeting of disease control activities. The aim of this study was to estimate the proportion of TB attributable to localised transmission for the period 2010-2012 in northern England and to identify case characteristics associated with spatiotemporal-genotypical clusters., Methods: We combined genotyping data with spatiotemporal scan statistics to define an indicator of localised TB transmission and identified factors associated with localised TB transmission thus defined in a multivariable logistics regression model., Results: The estimated proportion of TB cases in northern England attributable to localised transmission was 10% (95% CI 9% to 12%). Clustered cases (cases which were spatiotemporally clustered with others of identical genotype) were on average younger than non-clustered cases (mean age 34 years vs 43 years; p value <0.05). Being UK born (adjusted OR (aOR) 3.6, 95% CI 2.9 to 6.0), presenting with pulmonary disease (aOR 2.2, 95% CI 1.3 to 3.6) and history of homelessness (aOR 2.8, 95% CI 1.2 to 6.8) or incarceration (aOR 2.6, 95% CI 1.2 to 5.9) were independently associated with being part of a spatiotemporal-genotypical cluster in a multivariable model. Belonging to an ethnic group other than white or mixed/other was also significantly associated with localised transmission. We identified localised transmission in 103/1958 middle super output areas mostly in urban areas., Conclusions: Incorporating highly discriminatory genotyping data into spatiotemporal analysis of TB incidence is feasible as part of routine surveillance and can provide valuable information on groups at greater risk and areas with localised transmission of TB, which could be used to inform control measures, such as intensified contact tracing., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background/purpose: To investigate risk factors of latent tuberculosis infection (LTBI) among inpatients of chronic psychiatric wards with tuberculosis (TB) outbreaks., Methods: In April 2013, inpatients of four all-male wards with TB outbreaks were tested for LTBI using the QuantiFERON-TB Gold in Tube (QFT) method. Based on this investigation, a retrospective study was conducted to assess risk factors for LTBI. Inpatients exposed to cluster-A or cluster-B TB cases were defined as contacts of cluster-A or cluster-B, and others, as nonclustered contacts., Results: Among 355 inpatients with TB exposure, 134 (38%) were QFT-positive for LTBI. Univariate analysis showed that significant predictors for QFT-positivity were age, case-days of exposure to all TB cases (TB-all) and to sputum smear positive cases, number of source cases with cough, and exposure to cluster-A TB cases. Independent risk factors for LTBI were higher age [adjusted odds ratio (OR) 1.03, 95% confidence intervals (CI: 1.01-1.05)], TB-all exposure case-days ≥ 200 [adjusted OR 2.04 (1.06-3.92)] and exposure to cluster-A TB cases [adjusted OR 2.82 (1.30-6.12)] after adjustment for the sputum smear positivity, and cough variables of the source cases. The contacts of cluster-A had a greater risk of LTBI than did those of cluster-B, especially in the younger population (≤50 years) after adjustment [adjusted OR 2.64 (1.03-6.76)]., Conclusion: After TB outbreaks, more than one third of inpatients were QFT-positive for LTBI. Our findings suggest that, beside the infectiousness of source cases, intensity of exposure, and age of contacts, exposure to TB cases in potential genotyping clusters may be predictive for LTBI in this male psychiatric population., (Copyright © 2015. Published by Elsevier B.V.)

Background: Diagnosis and treatment of latent tuberculosis infection (LTBI) is a tool for global TB control, especially in close contacts. But data is scarce in high burden countries, under field conditions, including data on the benefits of LTBI management., Objective: To analyze the LTBI diagnosis and treatment cascade among contacts in primary health care (PHC) services in São José do Rio Preto-SP, Brazil., Methods: Cross-sectional design, conducted with contacts of pulmonary TB patients followed in all PHC services. Data was collected from May to September 2014 in the Reporting System for TB cases (TBWEB) and Reporting System for Chemoprophylaxis. Medical records and treatment follow-up forms were reviewed and all the nurses responsible for TB in PHC services were interviewed., Results: Among 336 contacts included, 267 (79.4%) were screened for TB or LTBI, according to the presence or not of respiratory symptoms. Among those contacts screened, 140 (52.4%) were symptomatic, 9 (3.4%) had TB disease, 106/221 (48%) had positive TST result, meeting the criteria for LTBI treatment, and 64/106 (60.4%) actually started it. Overall, among 267 screened, only 64 (24%) started LTBI treatment. The completion rates of treatment among the contacts who started it, those with positive TST result and those screened were 56.3% (36/64), 16.3% (36/221) and 13.5% (36/267), respectively. Nurses claimed that asymptomatic TB contacts pay no attention to preventive health care and do not seek medical care as they do not have symptoms of the disease. In reviewing the medical records, high proportions of contacts without evaluation, incomplete assessment, incorrect records of contraindication for LTBI treatment, lack of notes regarding the identification and evaluation of contacts were identified., Conclusions: There is a need for better organization of the surveillance and investigation routine for contacts in PHC, considering the reorganization of the work process and the features of the local health system.

Background: Household contacts (HHCs) of TB cases are at increased risk for TB disease compared to the general population but the risk may be modified by individual or household factors. We conducted a study to determine incident TB among HHCs over two years after exposure and to identify individual and household level risk factors., Methods: Adults newly diagnosed with a first episode of smear-positive pulmonary TB (index cases) between March 2010 and December 2011 in eastern Lima, were interviewed to identify their HHC and household characteristics. TB registers were reviewed for up to two years after the index case diagnosis and house visits were made to ascertain TB cases among HHC. The TB incidence rate ratio among HHCs as a function of risk factors was determined using generalized linear mixed models., Results: The 1178 index cases reported 5466 HHCs. In 402/1178 (34.1 %) households, at least one HHC had experienced a TB episode ever. The TB incidence among HHCs was 1918 (95%CI 1669-2194) per 100,000 person-years overall, and was 2392 (95%CI 2005-2833) and 1435 (95%CI 1139-1787) per 100,000 person-years in the first and second year, respectively. Incident TB occurred more than six months following the index case's TB diagnosis in 121/205 (59.0 %) HHCs. In HHCs, bacillary load and time between symptoms and treatment initiation in the index case, as well as the relationship to the index case and the sex of the HHC all had a significant association with TB incidence in HHCs., Conclusions: Incidence of TB among HHCs was more than ten times higher than in the general population. Certain HHC and households were at higher risk of TB, we recommend studies to compare HHC investigation to households at highest risk versus current practice, in terms of efficiency.

Objective: to analyze the feasibility of quality indicators for evaluation of hospital programs for preventing occupational tuberculosis., Method: a descriptive cross-sectional study. We tested indicators for evaluating occupational tuberculosis prevention programs in six hospitals. The criterion to define feasibility was the time spent to calculate the indicators., Results: time spent to evaluate the indicators ranged from 2h 52min to 15h11min 24sec. The indicator for structure evaluation required less time; the longest time was spent on process indicators, including the observation of healthcare workers' practices in relation to the use of N95 masks. There was an hindrance to test one of the indicators for tuberculosis outcomes in five situations, due to the lack of use of tuberculin skin test in these facilities. The time requires to calculate indicators in regarding to the outcomes for occupational tuberculosis largely depends upon the level of organizational administrative structure for gathering data.

Background: Tuberculosis (TB) remains a major public health problem. In 2013, 9 million new cases of active TB were estimated globally and the proportion of reported new cases with multi-drug resistance (MDR) was 3.5%., Methods: Contact tracing of a case of pulmonary tuberculosis was performed in a Bolivian patient. Diagnostic tests were performed according to national and local protocols., Results: An outbreak of tuberculosis in an immigrant community was detected, with 5 cases originating from one index case. Genotyping and drug susceptibility testing of the sputum samples determined Mycobacterium tuberculosis resistant to isoniazid (KatG-msp unmutated/inhA 5RBS CT). Active case finding revealed a total of 39 contacts with an incidence of latent infection of 71.43%., Conclusions: The present study confirms the importance of active case finding through contact tracing as well as rapid laboratory diagnosis to achieve improvements in early detection of TB. Early diagnosis of the patient, compliance with appropriate treatment protocols and monitoring of drug resistance are considered essential for the prevention and control of TB., (Copyright © 2015 SEPAR. Published by Elsevier Espana. All rights reserved.)

Objective: Recent guidelines recommend the use by healthcare personnel of a fit-tested N95 particulate respirator or higher-grade respiratory precaution in a patient undergoing bronchoscopy when pulmonary tuberculosis (PTB) is suspected. However, PTB may be unexpectedly diagnosed in this setting and therefore not evaluated, resulting in the unexpected exposure to Mycobacterium tuberculosis (MTB) of healthcare workers in the bronchoscopy suite. Here, we examined the incidence of unexpected exposure to MTB during flexible bronchoscopy and determined the exposure-related factors., Methods: Between 2011 and 2013, a retrospective study was conducted to evaluate unexpected diagnoses of PTB in the bronchoscopy suite. During the study period, 1650 consecutive patients for whom previous CT scans were available and who underwent bronchoscopy for respiratory disease other than PTB were included. The results of bronchial washing, bronchoalveolar lavage, and post-bronchoscopic sputum were reviewed., Results: PTB was unexpectedly diagnosed in 76 patients (4.6%). The presence of anthracofibrosis [odds ratio (OR), 3.878; 95% confidence interval (CI), 1.291-11.650; P = 0.016), bronchiectasis (OR, 1.974; 95% CI, 1.095-3.557; P = 0.024), or atelectasis (OR, 1.740; 95% CI, 1.010-2.903; P = 0.046) as seen on chest CT scan was independently associated with unexpected PTB. Patients with both anthracofibrosis and atelectasis were at much higher risk of unexpected PTB (OR, 4.606; 95% CI, 1.383-15.342; P = 0.013)., Conclusions: The risk of MTB exposure by healthcare personnel in the bronchoscopy suite due to patients with undiagnosed PTB has been underestimated. Therefore, in geographic regions with an intermediate PTB prevalence, such as South Korea (97/100,000 persons per year), higher-grade respiratory precaution, such as a fit-tested N95 particulate respirator, should be considered to prevent occupational exposure to MTB during routine bronchoscopy, especially in patients with CT-confirmed anthracofibrosis, bronchiectasis, or atelectasis.

Introduction: Mycobacterium tuberculosis (Mtb) is transmitted from person to person via airborne droplet nuclei. At the community level, Mtb transmission depends on the exposure venue, infectiousness of the tuberculosis (TB) index case and the susceptibility of the index case's social network. People living with HIV infection are at high risk of TB, yet the factors associated with TB transmission within communities with high rates of TB and HIV are largely undocumented. The primary aim of the Kopanyo study is to better understand the demographic, clinical, social and geospatial factors associated with TB and multidrug-resistant TB transmission in 2 communities in Botswana, a country where 60% of all patients with TB are also infected with HIV. This manuscript describes the methods used in the Kopanyo study., Methods and Analysis: The study will be conducted in greater Gaborone, which has high rates of HIV and a mobile population; and in Ghanzi, a rural community with lower prevalence of HIV infection and home to the native San population. Kopanyo aims to enrol all persons diagnosed with TB during a 4-year study period. From each participant, sputum will be cultured, and for all Mtb isolates, molecular genotyping (24-locus mycobacterial interspersed repetitive units-variable number of tandem repeats) will be performed. Patients with matching genotype results will be considered members of a genotype cluster, a proxy for recent transmission. Demographic, behavioural, clinical and social information will be collected by interview. Participant residence, work place, healthcare facilities visited and social gathering venues will be geocoded. We will assess relationships between these factors and cluster involvement to better plan interventions for reducing TB transmission., Ethics: Ethical approval from the Independent Review Boards at the University of Pennsylvania, US Centers for Disease Control and Prevention, Botswana Ministry of Health and University of Botswana has been obtained., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background/aims: The objective of this prospective study was to evaluate the diagnosis and treatment of latent tuberculosis infection (LTBI) in adult close contacts of active pulmonary tuberculosis (TB) patients in Korea., Methods: Adult close contacts of active pulmonary TB patients were recruited at a regional tertiary hospital in Korea. The participants were tested for LTBI using the tuberculin skin test (TST) and/or QuantiFERON-TB Gold (QFT-G) test. LTBI patients, who consented to treatment, were randomly assigned to receive isoniazid for 9 months (9INH) or rifampin for 4 months (4RIF)., Results: We examined 189 adult close contacts (> 18 years) of 107 active pulmonary TB patients. The TST and QFT-G were positive (≥ 10 mm) in 75/183 (39.7%) and 45/118 (38.1%) tested participants, respectively. Among 88 TST or QFT-G positive LTBI participants, 45 participants were randomly assigned to receive 4RIF (n = 21) or 9INH (n = 24), respectively. The average treatment duration for the 4RIF and 9INH groups was 3.3 ± 1.3 and 6.1 ± 2.7 months, respectively. Treatment was completed in 25 participants (4RIF, n = 16; 9INH, n = 9). LTBI participants who accepted treatment were more likely to be women and have more cavitary lesions on the chest radiographs of index cases and positive TST and QFT-G results compared to those who refused treatment., Conclusions: About 40% of adult close contacts of active pulmonary TB patients had LTBI; about 50% of these LTBI participants agreed to treatment.

We report a case of a 27-year-old anesthetist who acquired tuberculosis (TB) while performing general anesthesia in a renal transplant (RTX) patient who had donor-derived contagious TB. The anesthetist developed pleural TB 6 months after exposure. Contact investigations (CIs) did not include health care workers (HCWs) of the Department of Anesthesiology, thereby missing the opportunity for the early diagnosis and treatment of TB. Genomic fingerprinting revealed identical Mycobacterium tuberculosis (MT) isolates in the anesthetist and in the RTX patient. The recipient had acquired disseminated TB from the harvested renal graft. The donor (liver and kidneys), a 67-year-old immigrant, had died from brain death by cerebral herniation after a stroke. She had been treated for tuberculosis with a pneumectomy 40 years ago. Since that time, she had been suffering from latent tuberculous infection (TBI), but had been considered to have been cured.

Household contacts of tuberculosis patients are at high risk of infection and development of active disease. In this study we evaluated the cytokine production and mRNA expression of IFN-γ, TNF-α, IL-10&IL-6 stimulated with r32kDa M. bovis BCGAg in active pulmonary tuberculosis patients (APTB), household contacts (HHC) and healthy controls (HC). The results showed the stimulated levels of IFN-γ and TNF-α were low while IL-10 levels were high in APTB and HHC compared to HC. IL-6 has not shown any significant difference. The mRNA expression of TNF- α was 8 fold high in HCs compared to APTB and HHC. The IL-6 expression was 2.2 fold &1 fold less in APTB and HHC compared to HCs. Multinomial logistic regression analysis indicated that the stimulated levels of IFN-γ & IL-6 and sex significantly predicted the HHC group from HCs at p<0.05.In conclusion further follow up studies with r32kd antigen might help to identify the high risk individuals., (Copyright © 2016. Published by Elsevier B.V.)

Objective: To evaluate the yield and effectiveness of contact investigations conducted around potentially infectious tuberculosis (TB) patients with no positive respiratory culture for Mycobacterium tuberculosis in New York City (NYC)., Design: All TB patients without a positive respiratory culture from 2003 to 2012 were extracted from the NYC TB registry, and all patients eligible for contact investigation and their contacts were evaluated. Patients without a positive respiratory culture were defined as eligible for contact investigation if they had a respiratory nucleic acid amplification result positive for M tuberculosis, a cavitary chest radiograph, or a positive respiratory acid-fast bacilli smear., Setting: NYC, New York., Main Outcome Measures: To evaluate the yield of the investigations, the number of contacts identified and the outcome of testing was quantified. Potential transmission was defined on the basis of whether active TB patients were detected among the contacts and if a contact had a TB test conversion., Results: From 2003 to 2012, there were 2191 TB patients without a positive respiratory culture in NYC, 374 (17%) of which were considered eligible for contact investigation. A total of 11 096 contacts were identified around 300 (80%) eligible patients, 136 of whom had a diagnosis of TB infection; of those with TB infection who initiated preventive treatment, 66% completed treatment. Potential transmission was identified around 14 patients, with the identification of 2 additional cases of active TB and 15 contacts with TB infection test conversion., Conclusions: Conducting contact investigations around patients without a positive respiratory culture yielded evidence of possible transmission and led to the identification and treatment of new TB cases and those with TB infection. These findings suggest that these investigations should be conducted in settings where resources permit.

Pyrazinamide (PZA) is an important first-line anti-tuberculosis drug, however, there are relatively few available data on PZA resistant (PZA-R) rate in China. From June 2009 to June 2012, we selected 493 isolates from five field settings in China to investigate PZA-R by pncA gene sequencing. The result showed that PZA-R rate was 1.0% (2/196) among pan-susceptible isolates, 3.1% (4/130) among isoniazid (INH) mono-resistant isolates, 14.0% (6/43) among rifampin (RIF) mono-resistant isolates and 43.5% (54/124) among multidrug resistant (MDR) isolates. MDR tuberculosis (TB), RIF mono-resistance, and retreatment were found to be risk factors for PZA-R. Newly diagnosed PZA-R TB patients and clustered isolates with identical pncA mutations indicate that transmission of PZA-R isolates plays an important role in emergence of PZA-R TB. The results suggest that, it is necessary to conduct PZA susceptibility test among MDR isolates and modify the treatment regimens accordingly., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Computer-aided detection to identify and diagnose pulmonary tuberculosis is being explored. While both cavitation on chest radiograph and smear-positivity on microscopy are independent risk factors for the infectiousness of pulmonary tuberculosis it is unknown which radiographic pattern, were it detectable, would provide the greatest public health benefit; i.e. reduced transmission. Herein we provide that evidence., Objectives: 1) to determine whether pulmonary tuberculosis in a high income, low incidence country is more likely to present with "typical" adult-type pulmonary tuberculosis radiographic features and 2) to determine whether those with "typical" radiographic features are more likely than those without such features to transmit the organism and/or cause secondary cases., Methods: Over a three-year period beginning January 1, 2006 consecutive adults with smear-positive pulmonary tuberculosis in the Province of Alberta, Canada, were identified and their pre-treatment radiographs scored by three independent readers as "typical" (having an upper lung zone predominant infiltrate, with or without cavitation but no discernable adenopathy) or "atypical" (all others). Each patient's pre-treatment bacillary burden was carefully documented and, during a 30-month transmission window, each patient's transmission events were recorded. Mycobacteriology, radiology and transmission were compared in those with "typical" versus "atypical" radiographs., Findings: A total of 97 smear-positive pulmonary tuberculosis cases were identified, 69 (71.1%) with and 28 (28.9%) without "typical" chest radiographs. "Typical" cases were more likely to have high bacillary burdens and cavitation (Odds Ratios and 95% Confidence Intervals: 2.75 [1.04-7.31] and 9.10 [2.51-32.94], respectively). Typical cases were also responsible for most transmission events-78% of tuberculin skin test conversions (p<0.002) and 95% of secondary cases in reported close contacts (p<0.01); 94% of secondary cases in "unreported" contacts (p<0.02)., Conclusion: As a group, smear-positive pulmonary tuberculosis patients with typical radiographic features constitute the greatest public health risk. This may have implications for automated detection systems.

The incidence of tuberculosis decreases. However, clinical cases frequently raise questions, mainly in the context of contact tracing or when antimicrobial resistance is suspected. Empiric standard treatment consists of rifampin, isoniazid, ethambutol and pyrazinamide. This initial regimen aims to reduce the number of pathogenic germs while the consolidation therapy should eradicate the remaining pathogens. Treatment duration and adherence are crucial for cure. For the treatment of latent tuberculosis the traditional 6 to 9 months isoniazid regimen is still the treatment of choice. In complex cases such as tuberculosis in immunocompromised patients or if resistant tuberculosis is suspected, patients should be referred to a specialized center.

Background: People concentrated in congregated systems such as prisons, are important but often neglected reservoirs for tuberculosis transmission, and threaten those in the outside community. The condition is more serious in Africa particularly in Sub-Saharan Africa (SSA) due to its poor living conditions and ineffective health services., Objectives: This study was conducted to determine the prevalence of smear positive pulmonary tuberculosis and associated risk factors among prisoners in Hadiya Zone prison., Methods: A cross-sectional survey was carried out from May to June 2013 in Hadiya Zone prison. Prison inmates who had history of cough for at least a week were included in the study. Three morning sputum samples were collected from suspected inmates and examined through compound light microscopy. The data obtained was analyzed using statistical software like Epidata and STATA., Results: A total of 164 prisoners were included in the survey using active screening strategy and the point prevalence of smear positive pulmonary tuberculosis (PTB) in the prison was 349.2 per 100,000 populations; about three times higher than its prevalence in the general population. Even though lack of visit from family was the only variable identified as a risk factor for PTB (P = 0.029), almost all of the PTB positive cases were rural residents, farmers, male youngsters and those who shared cell with TB patients and chronically coughing persons as well as those who stayed in a cell that contains >100 inmates., Conclusion: There is high prevalence of TB in Hadiya Zone prison with possible active transmission of TB within the prison. The study also documented a number of factors which may facilitate exposures to TB though most of them are not significantly associated. Therefore, strong cooperation between prison authorities and the national tuberculosis control programmes is urgently required to develop locally appropriate interventions to reduce transmission.

Purpose: We report an outbreak of 64 cases of tuberculosis (TB) that spread in a welfare facility for elderly individuals., Objective and Methods: First, 64 TB patients who had contact with the source patient were screened at our hospital. We examined the time course up to the discovery of symptoms and analyzed the results for variable numbers of tandem repeats (VNTR) and the drug susceptibility tests. Second, we performed chest computed tomography to examine lesions due to a previous TB infection., Result: The source patient had recurrent aspiration pneumonia. The delay in doctor consultation was considered day 0, and the delay of diagnosis was 267 days. On examining the contacts, we found that 29 patients had TB while 35 had a latent TB infection. Results of the VNTR and the drug susceptibility tests showed that all the patients who developed TB had the same pattern as that of the source patient. Chest computed tomography showed lesions due to a previous TB infection in 8 patients., Conclusion: Based on the results of the VNTR and drug susceptibility tests, we concluded that the outbreak was due to an exogenous infection from the same source. All 8 patients who showed lesions due to a previous TB infection were aged > 81 years, and TB in these patients was found to be due to exogenous re-infection.

Mycobacterium bovis, one of several mycobacteria of the M. tuberculosis complex, is a global zoonotic pathogen that primarily infects cattle. Humans become infected by consuming unpasteurized dairy products from infected cows; possible person-to-person airborne transmission has also been reported. In April 2014, a man in Nebraska who was born in Mexico was determined to have extensive pulmonary tuberculosis (TB) caused by M. bovis after experiencing approximately 3 months of cough and fever. Four months later, a U.S.-born Hispanic girl from a nearby town who had been ill for 4-5 months was also determined to have pulmonary TB caused by M. bovis. The only social connection between the two patients was attendance at the same church, and no common dietary exposure was identified. Both patients had pulmonary cavities on radiography and acid-fast bacilli (AFB) on sputum-smear microscopy, indicators of being contagious. Whole-genome sequencing results of the isolates were nearly indistinguishable. Initial examination of 181 contacts determined that 39 (22%) had latent infection: 10 (42%) of 24 who had close exposure to either patient, 28 (28%) of 100 who were exposed to one or both patients in church, and one (2%) of 57 exposed to the second patient at a school. Latent infection was diagnosed in six contacts on follow-up examination, 2 months after an initial negative test result, for an overall latent infection rate of 25%. No infected contacts recalled consuming unpasteurized dairy products, and none had active TB disease at the initial or secondary examination. Persons who have M. bovis TB should be asked about consumption of unpasteurized dairy products, and contact investigations should follow the same guidance as for M. tuberculosis TB.

Background: Highly lethal outbreaks of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis are increasing. Mycobacterium tuberculosis variant Beijing family and its members is regarded as a successful clone of M. tuberculosis that is associated with drug resistance in China. Understanding the genetic characteristics and molecular mechanism of drug resistant tuberculosis within Beijing family may help to clarify its origin and evolutionary history and the driving forces behind its emergence and current dissemination., Methods: Totally of 1222 Mycobacterium tuberculosis isolates were recovered from patients in six counties of two provinces in eastern China within 2010/2012. Strain lineage and its major subgroups were studied respectively by using Spoligotyping and MIRU-VNTR. The 1st-line drug susceptibility was analyzed by proportional method and 2nd-line drug susceptibility was determined by the HAINs MTBDRsl test. The genetic characterization of drug resistance was analyzed by sequencing the previously reported genes and loci associated with drug resistance together with the multiple genotyping including MIRU-VNTR, Spoligotyping and LSP genotyping., Results: Of the 1222 Mtb isolates, 298 (24.4%) were resistant to 1st-line drug and 73 (5.9%) were simultaneously resistant to INH and RIF namely MDR-TB. Respectively 23.8% of 1st-line drug resistant TB and 12.0% of the drug susceptible TB contained the mutation associated with 2nd-line drugs by HAINs test. The Spoligotyping of 1222 Mtb isolates revealed the 967 (79.1%) of the isolates belonged to the W-Beijing family. Within W-Beijing family, 78.8% MDR-TB were observed in the isolates with simultaneous deletion of RD105 and RD207, with sub-lineage 181 accounting for 75% of MDR-TB. Analysis of 24 MIRU-VNTR loci revealed that 88.2% (15/17) of MDR and extensively drug resistant (XDR) clustered isolates were sub-lineage 181., Conclusions: Sublineage 181 might have the capacity to spread throughout the general community in rural China. This is the first report on the extensive association of sub-lineage 181 with MDR TB and possibly pre-XDR TB and XDR TB. It is important to monitor sublineage 181 to verify its heightened transmission and understand its importance in the global MDR-TB and XDR-TB epidemics., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective To determine tuberculosis (TB) knowledge, attitudes, practices, education and Tuberculin Skin Test (TST) positivity among Colombian health professions students in their last year of study. Methods A cross-sectional study was conducted using a self-reported questionnaire about TB knowledge, attitudes, practices and education with 193 students of medicine, nursing, dentistry, physical therapy, speech and language therapy, occupational therapy, clinical laboratory studies and emergency care. A TST was performed on 153 of the students. Results Although most of survey respondents perceived the TB education they received to be "sufficient", the results regarding their knowledge of TB do not support such perceptions: 35.2% of participants did not identify TB risk factors, 33.7 % of participants identified Colombian TB incidence, and only 1.6 % identified appropriate initial treatment for TB. In regards to practices, 50 % of respondents admitted that they would take care of a patient without a high efficiency mask. The TST was positive in 35 % of participants. Conclusions Our results show that there are opportunities to improve TB education in this health faculty, there is also a need to improve safety practices in the facilities where students work in order to reduce their risk of conversion.

We aimed to model the incidence of infection with Mycobacterium tuberculosis among adults using data on infection incidence in children, disease prevalence in adults, and social contact patterns. We conducted a cross-sectional face-to-face survey of adults in 2011, enumerating "close" (shared conversation) and "casual" (shared indoor space) social contacts in 16 Zambian communities and 8 South African communities. We modeled the incidence of M. tuberculosis infection in all age groups using these contact patterns, as well as the observed incidence of M. tuberculosis infection in children and the prevalence of tuberculosis disease in adults. A total of 3,528 adults participated in the study. The reported rates of close and casual contact were 4.9 per adult per day (95% confidence interval: 4.6, 5.2) and 10.4 per adult per day (95% confidence interval: 9.3, 11.6), respectively. Rates of close contact were higher for adults in larger households and rural areas. There was preferential mixing of close contacts within age groups and within sexes. The estimated incidence of M. tuberculosis infection in adults was 1.5-6 times higher (2.5%-10% per year) than that in children. More than 50% of infections in men, women, and children were estimated to be due to contact with adult men. We conclude that estimates of infection incidence based on surveys in children might underestimate incidence in adults. Most infections may be due to contact with adult men. Treatment and control of tuberculosis in men is critical to protecting men, women, and children from tuberculosis., (© The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.)

The statistical data of monthly pulmonary tuberculosis (TB) incidence cases from January 2004 to December 2012 show the seasonality fluctuations in Shaanxi of China. A seasonality TB epidemic model with periodic varying contact rate, reactivation rate, and disease-induced death rate is proposed to explore the impact of seasonality on the transmission dynamics of TB. Simulations show that the basic reproduction number of time-averaged autonomous systems may underestimate or overestimate infection risks in some cases, which may be up to the value of period. The basic reproduction number of the seasonality model is appropriately given, which determines the extinction and uniform persistence of TB disease. If it is less than one, then the disease-free equilibrium is globally asymptotically stable; if it is greater than one, the system at least has a positive periodic solution and the disease will persist. Moreover, numerical simulations demonstrate these theorem results.

As a setting for potential tuberculosis (TB) transmission and contact tracing, aircraft pose specific challenges. Evidence-based guidelines are needed to support the related-risk assessment and contact-tracing efforts. In this study evidence of TB transmission on aircraft was identified to update the Risk Assessment Guidelines for TB Transmitted on Aircraft (RAGIDA-TB) of the European Centre for Disease Prevention and Control (ECDC). Electronic searches were undertaken from Medline (Pubmed), Embase and Cochrane Library until 19 July 2013. Eligible records were identified by a two-stage screening process and data on flight and index case characteristics as well as contact tracing strategies extracted. The systematic literature review retrieved 21 records. Ten of these records were available only after the previous version of the RAGIDA guidelines (2009) and World Health Organization guidelines on TB and air travel (2008) were published. Seven of the 21 records presented some evidence of possible in-flight transmission, but only one record provided substantial evidence of TB transmission on an aircraft. The data indicate that overall risk of TB transmission on aircraft is very low. The updated ECDC guidelines for TB transmission on aircraft have global implications due to inevitable need for international collaboration in contract tracing and risk assessment.

Setting: Contact investigation of tuberculosis (TB) patients in Chilean prisons., Objective: 1) To estimate TB incidence and the prevalence of latent tuberculous infection (LTBI) among prisoners and their contacts; and 2) to determine factors associated with disease transmission., Design: Cross-sectional study conducted in 46 prisons (51% of the total prison population) to assess the prevalence of and risk factors for LTBI among contacts of prisoners newly diagnosed with pulmonary TB. We used in vitro interferon-gamma release assays to establish LTBI and a questionnaire to address risk factors., Results: During the 1-year follow-up, we studied 418 contacts of 33 active TB cases. We found high TB incidence (123.9 per 100,000 prisoners) and high LTBI prevalence (29.4%) among contacts. LTBI rates are significantly higher in prison inmates than in non-prisoners (33.2% vs. 15.6%). Male sex, illicit drugs, malnutrition, corticosteroid use, low educational level and sharing a cell with a case increase the risk of LTBI. Multivariate analyses showed that corticosteroid use, duration of incarceration and overcrowding are the most relevant determinants for LTBI among all contacts., Conclusions: Our results confirm that incarceration increases the risk of tuberculous infection and TB disease, and that it was associated not only with origin from vulnerable groups, but also with the prison environment. Reinforcing TB control is essential to prevent TB transmission in prisons.