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Infection tuberculosa entre trabajadores de combis en peru


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Infection tuberculosa entre trabajadores de combis en peru

  1. 1. Downloaded from on November 29, 2010 - Published by Pulmonary tuberculosis infection among workers in the informal public transport sector in Lima, Peru Olivia Janett Horna-Campos, Ezequiel Consiglio, Hector J Sánchez-Pérez, et al. Occup Environ Med published online November 23, 2010 doi: 10.1136/oem.2009.051128 Updated information and services can be found at: These include: References This article cites 11 articles, 4 of which can be accessed free at: P<P Published online November 23, 2010 in advance of the print journal. Email alerting Receive free email alerts when new articles cite this article. Sign up in the service box at the top right corner of the online article. NotesAdvance online articles have been peer reviewed and accepted for publication but have notyet appeared in the paper journal (edited, typeset versions may be posted when availableprior to final publication). Advance online articles are citable and establish publicationpriority; they are indexed by PubMed from initial publication. Citations to Advance onlinearticles must include the digital object identifier (DOIs) and date of initial publication.To request permissions go to: order reprints go to: subscribe to BMJ go to:
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Downloaded from on November 29, 2010 - Published by OEM Online First, published on November 23, 2010 as 10.1136/oem.2009.051128 Short report Pulmonary tuberculosis infection among workers in the informal public transport sector in Lima, Peru Olivia Janett Horna-Campos,1 Ezequiel Consiglio,2 Hector J Sanchez-Perez,3 ´ ´ 1 4 1 ` Albert Navarro, Joan A Cayla, Miguel Martı ´n-Mateo1 Unidad de Bioestadı´stica, ABSTRACTFacultad de Medicina, Background Because a strong association was observed What this paper adds ´Universidad Autonoma de between pulmonary tuberculosis (TB) and the use ofBarcelona, Barcelona, Spain2 ´ Escuela de Salud Publica, public transport, increasing with duration of journey, < An association between pulmonary tuberculosisFacultad de Medicina, a study was carried out to assess infection by and the use of public transport (minibus) hasUniversidad de Buenos Aires, Mycobacterium tuberculosis and working conditions previously been shown.Buenos Aires, Argentina among workers in this sector.3´ ´ Area Academica de Sociedad, < Moreover, the strength of this associationCultura y Salud, El Colegio de la Methods A cross-sectional study was conducted increases as trip duration increases.Frontera Sur, Chiapas, Mexico between June and September 2008. A total of 104 < We have observed an association between4 Servicio de Epidemiologı´a, workers from two public transport minibus (‘combi’) positive tuberculin skin test results and the poor ` ´Agencia de Salut Publica de cooperatives covering marginal areas of the Ate-VitarteBarcelona, CIBER de working conditions of minibus workers in district in Lima were interviewed. Demographic and a precarious occupational setting, characteristic ´a ´Epidemiologı y Salud Publica,Barcelona, Spain occupational details were collected as well as prior of low-income countries with high tuberculosis family and personal history of TB and BCG vaccination. prevalence.Correspondence to The tuberculin skin test (TST) was administered to each < Minibus workers in such countries shouldOlivia Janett Horna-Campos, study subject and an induration of $10 mm was therefore be included in occupational healthUnidad de Bioestadı´stica, GrupoGRAAL, Facultad de Medicina, considered positive. Statistical analysis was based on programs.Edificio M, Campus UAB, logistic models, ORs and their 95% CIs.Cerdanyola del Valles, 08193 Results TST results were obtained for 70.2% (n¼73), ofBarcelona, Spain; whom 76.6% (n¼56) were positive. Positivity significantly associated with those who had worked for The objective of this study was to evaluate theOJH-C, EC, HJS-P, AN and more than 2 years (crude OR 11.04; 95% CI 3.17 to risk of Mycobacterium tuberculosis infection in publicMM-M are members of GRAAL 38.43) and more than 60 h/week (crude OR 9.8; 95% CI transportation workers in the Ate-Vitarte district in `(Grups de Recerca d’America i 2.85 to 33.72). These associations remained significant Lima, a marginal area with high PTB prevalence.`Africa Llatines; http://www. in a multivariate model as Conclusion The association observed between years ofAccepted 23 June 2010 working and weekly work burden among minibus MATERIAL AND METHODS workers suggests an occupational risk in service jobs in Based on a previous study design in the trans- low-income countries with high TB prevalence. portation setting,2 two minibus cooperatives were Consequently, other types of users are at increased risk selected from 14 operating services to the study for TB infection, with a causal relationship between area. A total of 106 workers, 50 drivers and 56 fare- effect and duration of exposure. collectors over 15 years of age, volunteered and were included. They were fully informed of the objectives of the study and of the opportunity to enrol in a TB program when appropriate. Two INTRODUCTION workers undergoing active TB treatment were Smear-positive pulmonary tuberculosis (PTB) is excluded from the study and there were no refusals. a major public health problem due to its trans- The remaining 104 study participants were mission within the community. A person with interviewed at central bus stations. Demographic untreated smear-positive PTB can infect 10e15 and occupational data were collected, including age, people each year.1 Even when the transmission sex, years of employment in the transportation pattern is known, in most South American coun- sector, hours worked per day, number of days tries only household contacts are screened with no worked per week, and personal and family history screenings in work locations. Public transportation of TB. is a documented setting where people are exposed At the time of the interview, each subject was to TB infection and other airborne pathogens, administered the tuberculin skin test (TST) in particularly in countries with a high prevalence of accordance with the Peru Tuberculosis Program, PTB.2e4 The urban public transportation services in following the standard Mantoux technique1 Peru, as in other South American countries, have consisting of an intradermal injection of purified inadequate environmental conditions and a high protein derivative (PPD-RT 23 SSI 2UT (0.1 ml); risk of airborne pathogens. Vehicles are frequently Statens Serum Institut, Copenhagen, Denmark; over-crowded, regulations on the length of the obtained from the Peruvian National Institute of working day are ignored and break times are not Health).1 Indurations were measured 48e72 h after taken. Thus, overcrowding and increased worker administration and those $10 mm were considered exposure times represent an occupational risk. positive.5e8 Duration of employment was groupedHorna-Campos OJ, Consiglio E, author´(orHJ, et al. employer) 2010. Produced by BMJ Publishing ´ Copyright Article Sanchez-Perez their Occup Environ Med (2010). doi:10.1136/oem.2009.051128 Group Ltd under licence. 3 1 of
  3. 3. Downloaded from on November 29, 2010 - Published by Short reportinto 0e2 years and more than 2 years.5 Regarding exposure time, DISCUSSIONthe number of hours worked per week was calculated based on The validity of the TST is controversial because of its lowscheduled services and information from the Ministry of sensitivity and specificity, lack of reactivity due to immunolog-Transportation on vehicles, drivers and fare-collectors, and then ical depression, and cross-reactions with other mycobacterialcategorised into more or less than 60 h per week.9 It was esti- species.11 There are also some limitations to using it in adultmated that workers worked an average of 12 h per day, 5 days populations in countries with high TB prevalence, such as Peru.per week, exceeding the working hours officially established in However, it is still the most common technique for diagnosingPeru for all occupations (8 hours per day or 40 hours per week). TB infection,5 even among BCG-vaccinated populations,12 The study was approved by the Ethics Committee of Health because of its easy application and interpretation, and low cost.13Directorate IV (East Lima), Ministry of Health. The use of public transport was found to be a risk factor for PTB infection in a previous study conducted in the sameStatistical analysis geographical area,2 in which journey duration was used to assessA sample size was calculated to obtain 10% precision of the exposure. This theoretical framework led to our hypothesis thatestimated proportion of 60% of positive TSTs10 (n¼92) similar findings would be observed among subjects considered(a¼0.05). Subjects were chosen from only two companies so exposed to TB infection because they worked as minibusthat all workers in both companies could be studied (n¼104). (combi) drivers and fare-collectors.Subsequently, we included participants who returned within the Among the study population, 93.2% had arm scarsstipulated time for the TST reading. A sub-study of non- compatible with prior BCG vaccination. Given the character-responders was conducted using two-sided t tests for mean istics of the Peruvian TB Prevention Program and the mean agecontrasts and exact tests of proportions to detect possible biases. of the subjects, we calculated that they were vaccinated more Univariate and bivariate analyses, as well as a multivariate than 15 years ago (including those re-vaccinated after 6 years)logistic model, were preformed. ORs and 95% CIs were calcu- and thus it is unlikely prior vaccination influenced TSTlated. Data were analysed using SPSS v 15. results.13 Moreover, the association between occupational characteristics and M tuberculosis infection, adjusted for age,RESULTS provides a specific epidemiological profile given these workingA total of 104 workers were interviewed and administered a TST, conditions: an informal work setting, lack of a job contract,and of these 73 (70.2%) returned for the TST reading, of whom lack of fixed break times, no health insurance and no health56 (76.6%; 95% CI 66.9% to 86.3%) were TST positive. benefits. The mean (SD) age of the 73 who returned for the test reading In this context, the response rate obtained was optimal andwas 33.9 (9.1) years. None had a known history of TB, although perhaps linked to health concerns among these workers (datathree (4.1%) were uncertain. Nine (12.3%) stated they had not shown). The high rate of TST positivity of 76.6% (95% CIa close relative with TB. Arm scars compatible with prior BCG 66.9% to 86.3%) was higher than the results observed in contactvaccination were found in 68 (93.2%) subjects. tracing studies (55e61%)10 and suggests high exposure in this The 31 who did not return for the test reading were not setting.significantly different from responders with regard to age (mean Furthermore, the prolonged daily and weekly exposure30.1 years), BCG (87%), family history (9.7%), years in the job suggests that the association is not coincidental and that(64.5%) or hours worked per week (48.4%). a worker with active PTB is a transmission source for passengers. Fifty-one subjects (69.9%) had worked in public trans- Despite AFB+ TB presentation, some workers continueportation for more than 2 years and 50 (68.5%) worked more working, as shown by the two employees excluded from thethan 60 h per week. study, or may default from anti-TB treatment when signs and According to the bivariate analysis, no association was found symptoms have minimised14 or because of incompatibilitybetween a positive TST and a family history of TB (Fisher exact between their working hours and those of health centres.test, p¼0.105). A positive TST was found to be associated with Therefore, minibus workers and companies should be targetedmore than 2 years of employment (OR 11.04; 95% CI 3.17 to for specific and effective preventive interventions within occu-38.43) and with working more than 60 h per week (OR 9.8; 95% pational health programs.CI 2.85 to 33.72). When controlling for age using a logistic The characteristics revealed in our study show that there ismultivariate model, the following were associated with a posi- a risk of infection among urban transportation workers in citiestive TST result: more than 2 years of employment (adjusted OR with high TB prevalence. Furthermore, one must consider the15.6) and working more than 60 h per week (adjusted OR 12.7) repercussions for passengers. This association must be inter-(table 1). preted in the context of working and environmental conditions. Table 1 Predictive factors for tuberculin skin test positivity in workers in the informal public transport sector, Lima, Peru Variable TST+ n/N (%) Crude OR 95% CI Adjusted OR by age 95% CI Time in job #2 years 10/22 (45.5) 1 1 >2 years 46/51 (90.2) 11.04 3.17 to 38.43 15.66 3.25 to 75.35 Hours/week #60 h 11/23 (47.8) 1 1 >60 h 45/50 (90.0) 9.8 2.85 to 33.72 12.7 2.72 to 49.45 Age 1.02 0.96 to 1.08 1.06 0.98 to 1.15 Reference categories: #2 years in job and #60 h/week. TST, tuberculin skin test.2 of 3 ´ ´ Horna-Campos OJ, Consiglio E, Sanchez-Perez HJ, et al. Occup Environ Med (2010). doi:10.1136/oem.2009.051128
  4. 4. Downloaded from on November 29, 2010 - Published by Short report The transmission of TB in large cities in TB endemic countries 3. Riley RL, Mills CC, Nyka W, et al. Aerial dissemination of pulmonarywith increased circulation of resistant mycobacteria, such as tuberculosis. A two-years study of contagion in a tuberculosis ward. Am J Hyg 1959;70:185e96.Lima, Peru, makes the risk of infection even greater. Because all 4. Miller MA, Viboud C, Balinska M, et al. The signature features of influenzaanti-TB treatment is administered through outpatient facilities, pandemicsdimplications for policy. N Engl J Med 2009;360:2595e8.transmission in this setting can also include drug-resistant and 5. Quispe CV. High risk for tuberculosis in hospital physicians, Peru. Emerg Infect Dis [Letters]. (accessed 07 Julextremely drug-resistant TB strains.14 2002). In conclusion, a home-based directly observed treatment 6. Kang Young A, Won LH, Yoon H II, et al. Discrepancy between the tuberculin skinstrategy should be considered for confirmed TB patients to test and the whole-blood interferon? Assay for the diagnosis of latent tuberculosis infections in an indeterminate tuberculosis burden country. JAMAavoid exposure within the work place, such as the public 2005;293:2756e61.transportation sector. 7. Lee JY, Choi HJ, Park I-N, et al. Comparison of two commercial interferon? Assays for diagnosing Mycobacterium tuberculosis infection. Eur Respir JAcknowledgements We are grateful for the collaboration of the Epidemiology 2006;28:24e30.Office of East Lima Health Directorate, and to Dr Alfredo Bedoya, Dr Levi Flores and 8. Mori T, Mitsunori S, Yamagishi F, et al. Specific detection of tuberculosis infection.all personnel of the Santa Clara health micronetwork. Thanks also to Mr Juan An interferoneg based assay using new antigens. Am J Respir Crit Care MedHerrera Noblecilla, sub-director of transport regulation, Lima City Council. 2004;170:59e64. 9. ´ Relacion de unidades de transporte por ruta. Lima: Gerencia del Transporte Urbano. ´ ´Funding This work was funded partly by the Fundacion Autonoma Solidaria (FAS-UAB) partly by the Spanish Lung and Respiratory Diseases Society (SEPAR-Solidaria). asp (accessed 27 Mar 2009). 10. ´ ´ Fernandez Revuelta A, Arazo Garces P, Aguirre Errasti JM, et al. Estudio deCompeting interests None. contactos con enfermos tuberculosos. An Med Interna 1994;11:62e6.Ethics approval This study was conducted with the approval of the Ethics 11. Pai M, Zwerling A, Menzies D. Systematic review: T-cell-based assays for theCommittee of Health Directorate IV (East Lima), Ministry of Health. diagnosis of latent tuberculosis infection: an update. Ann Intern Med 2008;149:177e84.Provenance and peer review Not commissioned; externally peer reviewed. 12. Joos TJ, Miller WC, Murdoch DM. Tuberculin reactivity in bacille Calmette-Guerin´ vaccinated populations: a compilation of international data. Int J Tuberc Lung DisREFERENCES 2006;10:883e91. 1. ´ ´ Norma Tecnica de Salud para el Control de la Tuberculosis. Peru. NTS N 041/MINSA/ 13. Farhat M, Greenaway C, Pai M, et al. False-positive tuberculin skin tests: what is DGSP-V.01, 2006:12e13. /2008/ the absolute effect of BCG and non-tuberculous mycobacteria? Int J Tuberc Lung Dis en/index.htlm (accessed 10 Apr 2009). 2007;11:934e5. 2. ´ ´ ´ Horna-Campos OJ, Sanchez-Perez HJ, Sanchez I, et al. Public transportation and 14. Mendoza Ay, Gotuzo E. Tuberculosis extremadamente resistente (TB-XDR): historia pulmonary tuberculosis, Lima, Peru. Emerg Infect Dis 2007;13:1491e3. ´ ´ y situacion actual. Acta Medica Peruana 2008;25:236e46. ´ ´Horna-Campos OJ, Consiglio E, Sanchez-Perez HJ, et al. Occup Environ Med (2010). doi:10.1136/oem.2009.051128 3 of 3