Tuberculosis contacts are candidates for active and latent tuberculosis infection screening and eventual treatment. However, many losses occur in the different steps of the contacts’ cascade of care. Reasons for this are poorly understood.
To describe the different steps where losses in the contact cascade occur and to explore knowledge and attitudes regarding tuberculosis transmission/prevention and perceptions about tuberculosis services in order to understand the reasons for losses from the tuberculosis service users’ perspective.
We collected routine data from the index case and contact registry books and from patients’ records to build the cascade of care of contacts in 12 health facilities in three Brazilian cities with high tuberculosis incidence rates. During a knowledge, attitudes and practices (KAP) survey, trained interviewers administered a semi-structured questionnaire to 138 index cases and 98 contacts.
Most of the losses in the cascade occurred in the first two steps (contact identification, 43% and tuberculin skin testing placement, 91% of the identified contacts). Among KAP-interviewed contacts, 67% knew how tuberculosis is transmitted, 87% knew its key symptoms and 81% declared they would take preventive therapy if prescribed. Among KAP-interviewed index cases, 67% knew they could spread tuberculosis, 70% feared for the health of their families and 88% would like their family to be evaluated in the same services.
Only a small proportion of contacts are evaluated for active and latent tuberculosis, despite their—and their index cases’—reasonable knowledge, positive attitudes towards prevention and satisfaction with tuberculosis services. In these services, education of service users would not be a sufficient solution. Healthcare workers’ and managers’ perspective, not explored in this study, may bring more light to this subject.
Citation: Salame FM, Ferreira MD, Belo MT, Teixeira EG, Cordeiro-Santos M, Ximenes RA, et al. (2017) Knowledge about tuberculosis transmission and prevention and perceptions of health service utilization among index cases and contacts in Brazil: Understanding losses in the latent tuberculosis cascade of care. PLoS ONE 12(9): e0184061. https://doi.org/10.1371/journal.pone.0184061
Editor: Seyed Ehtesham Hasnain, Indian Institute of Technology Delhi, INDIA
Received: April 28, 2017; Accepted: August 17, 2017; Published: September 21, 2017
Copyright: © 2017 Salame et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All data files are available from the correspondent author Anete Trajman.
Funding: The project was funded by CNPq (456901/2013-2) and the Canadian Institutes of Health Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
The World Health Organization (WHO) considers investigation of tuberculosis (TB) index case contacts a fundamental activity to control TB, a disease that still affects approximately 10.4 million people and kills 1.4 million a year globally. Contact investigation helps to identify active TB disease and latent Mycobacterium tuberculosis infection (LTBI) in contacts. Those with LTBI are at high risk for progression to active disease, thus they are an important reservoir for new TB cases. The treatment of LTBI with isoniazid (INH) substantially reduces this risk by up to 90%.
Although prophylactic regimens have been recommended by the American Thoracic Society and by WHO since 1970's, under routine conditions rates of LTBI treatment completion are low. Non-adherence to treatment is just a part of the problem. A recent systematic review on the cascade of care in diagnosis and treatment of LTBI confirmed that important losses occur at each of the steps of initial screening, completing medical evaluation, and starting therapy. This phenomenon was observed in both high-income and low- and medium-income countries. Thus, actions to prevent losses in the pre-treatment steps could likely result in more impact in LTBI treatment outcomes than non-adherence problems.
Few studies have explored the extent, risk factors and reasons for the losses in the pre-treatment LTBI phase from the patients’ and contacts’ perspective.[11,12] Most knowledge, attitudes and practice (KAP) surveys on LTBI have focused on health professionals,[13,14] on high-risk populations (such as, the immigrants, the homeless and the African-Americans) and on difficulties in adherence to treatment and side effects of medications. To our knowledge, no studies have explored this issue from the contacts’ perspective and only two from the perspective of health services users (herein called users).[17,19]
In Brazil, the Ministry of Health currently recommends treating LTBI in all eligible TB contacts, i.e., contacts of any age with a positive tuberculin skin test (TST) and no signs of active TB on chest radiograph, with INH for six to nine months. Thus, contact investigation in Brazil should start with an interview to detect symptoms and a TST. Those with symptoms or a positive TST should undergo full medical evaluation, including a chest radiograph. A recent study in Rio de Janeiro found that, among 1078 pediatric contacts, the most important losses occurred before INH prescription (206/322 with tuberculin skin test -TST- positive, 64%), in the investigation process, while 63% of those prescribed INH (73/115) completed treatment. Healthcare workers attribute low attendance to LTBI programs in Brazil to insufficient knowledge, unaffordable costs and lack of interest in contacts,[21–23] but this remains to be proven. Therefore, we evaluated the cascade of LTBI care among Brazilian contacts and conducted a KAP survey regarding TB transmission and prevention, perceptions about health services utilization and patients’ health costs in three state capitals with high TB incidence rates: Recife (78.3/100,000 population/year), Rio de Janeiro (66.8/100,000) and Manaus (98.3/100,000).
This was an observational cross-sectional study. For the survey, we used a Knowledge, Attitudes and Practice (KAP) design, a representative study of a specific population to collect information on what is known, believed (attitudes) and done (practice) in relation to a particular topic.[25,26], In most KAP studies, data are collected by an interviewer using a structured, standardized questionnaire. These data can then be analyzed in a quantitative or qualitative format, according to research objectives. A KAP survey may be specially designed to collect information about a topic, but it is also possible to include general questions about practices and beliefs. No interventions were made by the research team as part of this study.
The study was conducted in Brazil. Three cities among the four highest TB incidence rates in the country were included: Manaus, Rio de Janeiro and Recife.
Brazil is an upper middle-income country with very sharp inequities in income and health. Its GINI index is 51.5. It is among the top 30 high TB burden countries according to WHO. TB treatment is restricted to public free-of-charge health clinics. Since 2010, the National TB Program recommends screening of LTBI for all contacts, regardless of age or co-morbidity. Contacts are screened for symptoms and a TST is performed in the initial visit. For those who are positive for any of the two, full medical evaluation including a chest radiograph are indicated. For those who are asymptomatic, TST-positive and no signs of active TB in the chest radiograph, LTBI treatment is recommended.
Identification of clusters
In the three participating capitals, we identified the number of new TB cases notified per health unit per year and selected, in each city, the four units with the highest number of cases to be included as data collection sites. Those were mostly primary care clinics with some having reference services for TB treatment.
Data regarding the steps of the cascade of care were collected from routine clinic sources. The national TB registry book (used by all clinics in the country), the TST book (used by some clinics) or index case and, when available, contact medical records and prescription lists and other sources of information routinely used by the clinics were consulted. Data were collected for the first semester of 2014, when there was full availability of PPD in the country (because of the shortage in the international market, PPD distribution was limited from July 1st 2014).
A semi-structured questionnaire previously applied in Indonésia addressing questions about TB transmission and prevention, attitudes and beliefs regarding LTBI and their perception regarding TB services was forward- and back-translated by independent translators and adapted to the Brazilian context. Questions about payment of visits, diagnostic tests and TB medication, for example, were suppressed, since TB care is only provided in public free-of-charge clinics, where we conducted the interviews. Open-ended questions were mostly objective, no options of answers were offered. The questionnaire was tested and refined in a pilot study done in Rio de Janeiro approaching 28 index cases and 19 contacts. During this pilot, we labeled and grouped answers, until new responses appeared very infrequently. For example, LTBI is diagnosed by TST, by PPD, by a test in the skin, were all considered as “diagnosed by TST”. During this whole process, responses not previously included were added.
The entire interview process took place from March 11, 2015 to October 21, 2015, during different periods in each city (because of local ethical clearance). Interviewers were previously trained to standardize the approach to the participants for consent and the application of the questionnaire. The training was carried out approximately one month before the beginning of the data collection by the principal investigator of the research project in Brazil (AT), in each of the three participating cities. The teams comprised two to three interviewers in each city. During the training, interviews supervised by the principal investigator were conducted with volunteers.
Patients treated for bacteriologically confirmed (smear microscopy, rapid molecular test or culture) pulmonary TB and their close contacts (those who shared an enclosed space, such as a social gathering place, workplace, or facility, with the index case for extended daytime periods during the 3 months before the start of the current treatment episode) at the 12 health centers during the data collection period were eligible for the interview. Consenting close contacts were recruited regardless of their LTBI status. Those under 18 years were excluded. In the clinics, participants were interviewed in a private space (in general, a consultation room). The sample size at each clinic varied according to the number of staff, patients and contacts eligible during the time period of the study.
Data were stored in a Microsoft Office Excel 2010 system spreadsheets. The frequencies, means and median values were calculated using the IBM SPSS Statistics software 23.
Answers were classified as satisfactory when "compulsory" responses were cited and if "unacceptable" answers were not mentioned. For example, knowledge about TB transmission was considered satisfactory if the respondent correctly identified the primary transmission route as airborne (i.e. “contact with someone with TB who sneezes, speaks or cough" or "living with someone who has TB") AND if they did not express misleading conceptions that could interfere with their practices (such as "It was a God’s decision"), even if (s)he also expressed other misconceptions (such as “using the same utensils”).
Cascade of LTBI care
Overall, 814 contacts from 339 registered index cases were identified (mean = 2.4 contacts/index case) in the records. Out of these, 73 (8.9%) underwent TST of whom 12 (16.4%) did not have TST read and 27 (36.9% of those read, or 3.3% of all contacts) were TST positive. All 27 started LTBI treatment, of whom 17 (62.9% of those who started treatment or 2.1% of all contacts and approximately 5.7% of all contacts estimated to have LTBI) completed treatment (Fig 1).
According to routinely collected data in the clinic, there were approximately 290 cases prospectively diagnosed in the 12 units during the interview study period, with approximately 410 close contacts, which constituted the eligible population for the interviews. They were approached if they were present on the day of data collection in their respective clinics. Among 138 index cases and 100 contacts across the three sites on the designated survey days, only two contacts refused to participate in the study. Eleven of 19 contacts were interviewed at home in Rio, two of 42 in Recife and none of 37 in Manaus. Their median age was 40 years [interquartile range (IQR) = 31 to 54.5] and 42 years [IQR = 30.5 to 53], respectively. The average duration of the interview with index cases was 10 minutes (IQR = 6 to 15) and with contacts, 11 minutes (IQR = 9 to 16).
Contacts´ knowledge and beliefs about TB are shown in Table 1. Knowledge about TB transmission and symptoms was satisfactory (67% and 87% respectively) and 28% knew how to prevent the disease. Half of them (52%) believed they could develop TB in the future, and 17% thought they were infected with Mycobacterium tuberculosis. Many (61%) believed they could spread TB to other people, except in Rio de Janeiro, where only 26% believed. When asked if they would take medicines to prevent TB if prescribed by the doctor, 81% answered positively. However, in Rio de Janeiro, only a minority (22%) said they would (Table 1).
Table 2 displays contacts´ perceptions of health services. Forty-three percent informed they had already performed or would perform TB tests. Among them, more were—or were scheduled to be—submitted to smear microscopy (22/42, 52%) and chest radiographs (20/42, 50%) than to TST (14/42, 33%). Only 21% reported that the health team alerted them that they could be sick or infected. Among the 56 contacts not investigated or scheduled for any investigation, the main reasons were believing they were not sick (42%) and tests not being proposed by the health team (36%). None of the respondents mentioned they could not afford the transportation costs and only one attributed lack of health-facility engagement to distance from their domicile.
About two thirds of contacts said they incurred out-of-pocket expenditures [at an average of 7.80 American dollars (USD); minimum wage in Brazil in 2015 = 236.56 USD] and 6% declared opportunity costs (i.e., absence from work/school had consequences), as displayed in Table 3.
There were no significant differences in knowledge or attitudes related to LTBI investigation and treatment according to sex, schooling and city, apart from the specificities in Rio described above (Table 4).
Table 5 displays knowledge and beliefs about TB reported by index cases. Seventy-three percent declared they feared dying from TB, 67% believed they could transmit TB, but only 23% understood how they got the disease. The main misconceptions regarding transmission included having inadequate nutrition, drinking alcohol, smoking, exposure to pollution and overwork. As for their attitudes, 94% said they had shared or would share with their families the diagnosis of TB and 88% would like their family members to be investigated for TB and LTBI. Fear of social rejection was mentioned by 10% of the cases. Most were satisfied with the clinics. There were no major differences in the number of satisfactory answers according to the variables analyzed in the present study (sex, city, schooling and family income, Table 6).
In the present study, designed to understand where (cascade) and why (interviews) losses in the cascade of LTBI care occur, we explored the users’ perspective. We observed very low rates of LTBI investigation among contacts as observed in other countries.[8,32–34] Losses occurred mainly in the first steps–identification and investigation–and this was confirmed by the questionnaires. Indeed, much more contacts (4.2 contacts/index case) were expected. More importantly, the great majority of identified contacts were never investigated for LTBI. Losses in the first steps were recognized in a systematic review both in high- and in low- and medium-income countries, but the magnitude of these losses in the current study were much higher. Many TB cases could be avoided in Brazil if all contacts were investigated.
Interestingly, however, the majority of contacts would like to have been investigated and would take preventive therapy if prescribed, which represents, in this case, a lost opportunity. Likewise, their index case would like them to be investigated and treated for TB or LTBI. In contrast, healthcare workers’ in Brazil reported perceptions that contacts wouldn’t or do not engage TB services because they do not understand the importance of TB or because index cases fear stigma and do not share their diagnosis with their contacts. Their perceptions are not supported by the present study.
Contacts who did undergo evaluation were mostly investigated for active TB, seldom for LTBI. Indeed, sputum smear and chest radiographs were performed for over half the contacts that attended clinics. Our cascade refers to the period when PPD was fully available in the international market. Thus, barriers for contact investigation in Brazil go beyond the availability of PPD.
The reasons for low rates of contact investigation for LTBI do not appear to rest with the contacts themselves or their index cases in Brazil. They have a reasonable knowledge of their risk, they do fear TB–unlike reports from other populations-[15,37] and most understand the disease can be prevented. Furthermore, index cases fear for their family, they would like their contacts to be investigated and treated, and recognize the importance of these procedures. Fear of social rejection or stigmatization was not an issue, unlike reported in other studies.[15,17] Moreover, they are satisfied with the services they attend and costs do not seem to be a barrier. Thus, overall, both index cases and contacts had a good attitude towards LTBI investigation and treatment.
Why then are so few contacts investigated in clinics in Brazil? According to their view, one of the main reasons was they were not invited by the health team, a finding reported in previous studies. We are currently investigating knowledge, attitudes and practices of healthcare workers in the same clinics in order to have a broader picture, with different perspectives.
Contacts in Rio had a different perception and were less knowledgeable compared to those in the two other cities. At least in part, this is likely to reflect that the majority of contacts in Rio were interviewed at home. Contacts that do not go to the clinics may well be different from those who attend visits either with their index case or after responding to the request of a healthcare worker. Our study has other limitations. In-depth understanding of reasons for an observed phenomenon usually needs qualitative methods. We did not explore factors linked to knowledge, attitudes and beliefs based on theoretical models. This was outside the scope of the present research. In addition, in studies based on interviews, respondents may not feel confident about responding to questions they think could be disapproved by the interviewer or the clinic staff, a potential source of bias. However, interviewers in this study were not part of the clinic staff. Finally, the sample is small and does not include children, although the questionnaire contained questions regarding close contact children and families with and without children were included in the sample.
In summary, there is a very low rate of investigation for LTBI of TB contacts in three high burden cities in Brazil. Contacts’ knowledge, attitudes and service perceptions do not seem to be the main reason for this finding. On the contrary, their will to be treated should be better explored by the health team and TB programs. Contact and index case education would not be enough to overcome the barriers. We suggest that interventions should be tailored to local values and cultures, which may vary even in the same country. The findings of the present study will be presented to TB managers and clinic staff in each unit in order to collectively find reasonable, feasible and sustainable solutions.
S1 Table. Database of the contacts interviewed during the survey.
The project was funded by CNPq (456901/2013-2) and the Canadian Institutes of Health Research. MDSF, GGS and AT are CNPq´s grantees. AT is member of the Technical Advisory Committee of the National Tuberculosis Control Program from the Brazilian Ministry of Health. The results and statements in this manuscript are of entire responsibility of the authors and do not reflect opinions from funders or the Ministry of Health. The authors report no conflicts of interest.
- 1. Hopewell PC, Fair E, Miller C, World Health Organization. Recommendations for investigating contacts of persons with infectious tuberculosis in low- and middle-income countries. Geneva, Switzerland: World Health Organization; 2012.
- 2. World Health Organization. Global tuberculosis report 2016. WHO. World Health Organization; 2017.
- 3. Fox GJ, Barry SE, Britton WJ, Marks GB. Contact investigation for tuberculosis: a systematic review and meta-analysis. Eur Respir J. 2013;41: 140–156. pmid:22936710
- 4. Smieja MJ, Marchetti CA, Cook DJ, Smaill FM. Isoniazid for preventing tuberculosis in non-HIV infected persons. Cochrane database Syst Rev. 2000; CD001363. pmid:10796642
- 5. World Health Organization. Guidelines on the management of latent tuberculosis infection. World Health Organization; 2015.
- 6. Menzies D, Long R, Trajman A, Dion MJ, Yang J, Al Jahdali H, et al. Adverse events with 4 months of rifampin therapy or 9 months of isoniazid therapy for latent tuberculosis infection: A randomized trial. Ann Intern Med. 2008;149: 689–697. pmid:19017587
- 7. Fiske CT, Yan F-X, Hirsch-Moverman Y, Sterling TR, Reichler MR. Risk factors for treatment default in close contacts with latent tuberculous infection. Int J Tuberc Lung Dis. International Union Against Tuberculosis and Lung Disease; 2014;18: 421–7. pmid:24670696
- 8. Alsdurf H, Hill PC, Matteelli A, Getahun H, Menzies D, Cain K, et al. The cascade of care in diagnosis and treatment of latent tuberculosis infection: a systematic review and meta-analysis. Lancet Infect Dis. Elsevier; 2016;0: 75–79.
- 9. Jereb J, Etkind SC, Joglar OT, Moore M, Taylor Z. Tuberculosis contact investigations: outcomes in selected areas of the United States, 1999. Int J Tuberc Lung Dis. 2003;7: S384–90. pmid:14677827
- 10. Silva APB, Hill P, Belo MTCT, Rabelo SG, Menzies D, Trajman A. Non-completion of latent tuberculous infection treatment among children in Rio de Janeiro State, Brazil. Int J Tuberc Lung Dis. 2016;20: 479–86. pmid:26970157
- 11. Levesque JF, Dongier P, Brassard P, Allard R. Acceptance of screening and completion of treatment for latent tuberculosis infection among refugee claimants in Canada. Int J Tuberc Lung Dis. 2004;8: 711–7. pmid:15182140
- 12. Richards B, Kozak R, Brassard P, Menzies D, Schwartzman K. Tuberculosis surveillance among new immigrants in Montreal. Int J Tuberc Lung Dis. 2005;9: 858–64. pmid:16104631
- 13. Pathak V, Harrington Z, Dobler CC. Attitudes towards preventive tuberculosis treatment among hospital staff. PeerJ. 2016;4: e1738. pmid:26966667
- 14. Zhou F, Zhang L, Gao L, Hao Y, Zhao X, Liu J, et al. Latent tuberculosis infection and occupational protection among health care workers in two types of public hospitals in China. PLoS One. 2014;9: e104673. pmid:25157814
- 15. Gao J, Berry NS, Taylor D, Venners SA, Cook VJ, Mayhew M. Knowledge and Perceptions of Latent Tuberculosis Infection among Chinese Immigrants in a Canadian Urban Centre. Int J Family Med. 2015;2015: 546042. pmid:26690263
- 16. Nyamathi A, Sands H, Pattatucci-Aragón A, Berg J, Leake B. Tuberculosis knowledge, perceived risk and risk behaviors among homeless adults: effect of ethnicity and injection drug use. J Community Health. 2004;29: 483–97. pmid:15587347
- 17. Royce RA, Colson PW, Woodsong C, Swinson-Evans T, Walton W, Maiuri A, et al. Tuberculosis Knowledge, Awareness, and Stigma Among African-Americans in Three Southeastern Counties in the USA: a Qualitative Study of Community Perspectives. J racial Ethn Heal disparities. 2015; pmid:26715219
- 18. Kane M, Korn B, Saukkonen J, McDonald C, Walsh C, Waters R, et al. Barriers to accepting and completing latent tuberculosis infection treatment. Ir Med J. 106: 200–4. pmid:24218745
- 19. Rakotosamimanana S, Mandrosovololona V, Rakotonirina J, Ramamonjisoa J, Ranjalahy JR, Randremanana RV, et al. Spatial Analysis of Pulmonary Tuberculosis in Antananarivo Madagascar: Tuberculosis-Related Knowledge, Attitude and Practice. PLoS One. 2014;9: e110471. pmid:25386655
- 20. Ministério da Saúde. Secretaria de Vigilância em Saúde. Programa Nacional de Controle da Tuberculose. Manual de Recomendações para o Controle da Tuberculose. Brasília: Ministério da Saúde; 2010.
- 21. MFW Pereira, MDS Ferreira, R Ximenes, MFM Albuquerque, MC Santos, EG Teixeira, FlM Salame, J Silva, G Salgado, AB Melo, M Belo AT. Conhecimentos, percepções e práticas em tuberculose de profissionais de nível médio da saúde de três municípios com alta carga de tuberculose no Brasil. Macéio: 52o Congresso da Sociedade Brasileira de Medicina Tropical; p. Prevision Screen on August 2016.
- 22. MDS Ferreira, MC Santos, MFPM Albuquerque, MFW Pereira, AB Melo, G Salgado, DC Cordeiro, JS Pinheiro, JR Silva AT. Conhecimentos, atitudes e práticas de médicos e enfermeiros da atenção primária sobre infecção latente tuberculosa em três capitais brasileiras de alta taxa de incidência. Macéio: 52o Congresso da Sociedade Brasileira de Medicina Tropical; 2016.
- 23. Wysocki AD, Villa TCS, Arakawa T, Brunello MEF, Vendramini SHF, Monroe AA, et al. Latent Tuberculosis Infection Diagnostic and Treatment Cascade among Contacts in Primary Health Care in a City of Sao Paulo State, Brazil: Cross-Sectional Study. Caylà JA, editor. PLoS One. Public Library of Science; 2016;11: e0155348. pmid:27285720
- 24. Ministério da Saúde. Secretaria de Vigilância em Saúde. Programa Nacional de Controle da Tuberculose. Boletim epidemiológico: Perspectivas brasileiras para o fim da tuberculose como problema de saúde pública. 2016.
- 25. World Health Organization. A guide to developing knowledge, attitude and practice surveys. Switzerland: WHO Library Cataloguing-in-Publication Data; 2008.
- 26. Jullien FGCP. Knowledge, Attitudes and Practices for Risk Education: how to implement KAP surveys—Guideline for KAP survey managers. 2009. ISBN: 978-2-909064-21-5
- 27. Secretaria de Vigilância em Saúde. Boletim Epidemiológico: Indicadores prioritários para o monitoramento do Plano Nacional pelo Fim da Tuberculose como Problema de Saúde Pública no Brasil. Brazil; 2017.
- 28. World Bank Group. GINI index (World Bank estimate) | Data [Internet]. 2014 [cited 18 Mar 2017]. Available: http://data.worldbank.org/indicator/SI.POV.GINI?locations=BR
- 29. Rutherford M, Ruslami R, Anselmo M. Management of children exposed to Mycobacterium tuberculosis: a public health evaluation in West Java, Indonesia. Bull WHO Press. 2013; Article ID: BLT.13.118414.
- 30. World Health Organization. WHO | Process of translation and adaptation of instruments. In: WHO [Internet]. World Health Organization; 2010 [cited 13 Jul 2017]. Available: http://www.who.int/substance_abuse/research_tools/translation/en/
- 31. Stop TB Partnership Childhood TB Subgroup World Health Organization. Guidance for National Tuberculosis Programmes on the management of tuberculosis in children. Chapter 1: introduction and diagnosis of tuberculosis in children. Int J Tuberc Lung Dis. 2006;10: 1091–7. pmid:17044200
- 32. Arscott-Mills T, Masole L, Ncube R, Steenhoff AP. Survey of health care worker knowledge about childhood tuberculosis in high-burden centers in Botswana. Int J Tuberc Lung Dis. 2017;21: 586–591. pmid:28399975
- 33. Noé A, Ribeiro RM, Anselmo R, Maixenchs M, Sitole L, Munguambe K, et al. Knowledge, attitudes and practices regarding tuberculosis care among health workers in Southern Mozambique. BMC Pulm Med. BioMed Central; 2017;17: 2. pmid:28056943
- 34. Subbaraman R, Nathavitharana RR, Satyanarayana S, Pai M, Thomas BE, Chadha VK, et al. The Tuberculosis Cascade of Care in India’s Public Sector: A Systematic Review and Meta-analysis. Murray M, editor. PLOS Med. 2016;13: e1002149. pmid:27780217
- 35. Fox GJ, Barry SE, Britton WJ, Marks GB. Contact investigation for tuberculosis: a systematic review and meta-analysis. Eur Respir J. European Respiratory Society; 2013;41: 140–56. pmid:22936710
- 36. Trajman A, Ferreira MDS, Salgado G, Melo AB Wakoff-Pereira M, Carreira Belo MT Teixeira EG, Martins ABS, Cornelio SC, et al. A public health evaluation of contact tracing and management in Brazil. the International Union Against Tuberculosis and Lung Disease, editor. Int J Tuberc Lung Dis. Liverpool; 2016;20: 527. Available: http://www.abstractserver.com/union2016/abstractbook/index.html
- 37. Agho KE, Hall J, Ewald B. Determinants of the knowledge of and attitude towards tuberculosis in Nigeria. J Health Popul Nutr. 2014;32: 520–38. pmid:25395915
- 38. Kall MM, Coyne KM, Garrett NJ, Boyd AE, Ashcroft AT, Reeves I, et al. Latent and subclinical tuberculosis in HIV infected patients: a cross-sectional study. BMC Infect Dis. BioMed Central; 2012;12: 107. pmid:22558946