Diagnostic value of the reaction at the bacillus calmette-guérin vaccination site in kawasaki disease / Utilidade diagnóstica da reação do sítio de vacinação bacillus calmette-guérin na doença de kawasaki

ABSTRACT Objective: To describe the case of an infant - diagnosed with incomplete Kawasaki disease - who developed BCG scar reactivation. Case description: A 6-month-old patient was admitted to hospital with fever associated with ocular hyperemia, cervical lymphadenopathy, and hyperemic lips, and remained hospitalized for 12 days. The physical examination revealed an inflammatory reaction at the site of the BCG scar, leading to the diagnosis of incomplete Kawasaki disease. The patient was treated with venous immunoglobulin, but presented recurrence of Kawasaki disease, with subsequent onset of coronary artery disease. Comments: BCG scar reactivation is an important finding in countries where the vaccine is routinely given and may be a useful marker for early diagnosis of Kawasaki disease, especially in its incomplete form.

RESUMO Objetivo: Descrever o caso de um lactente - com diagnóstico de Doença de Kawasaki incompleta - que desenvolveu reativação da cicatriz da vacina BCG. Descrição do caso: Um paciente de 6 meses de idade foi admitido no hospital com febre, associada à hiperemia ocular, linfadenomegalia cervical e fissuras labiais, permanecendo hospitalizado por 12 dias. Apresentava, no exame físico, reação inflamatória no local da cicatriz da vacina BCG, tendo sido feito o diagnóstico de Kawasaki incompleto. O paciente foi tratado com imunoglobulina venosa, mas apresentou recorrência da doença, com posterior surgimento de coronariopatia. Comentários: A reativação da BCG é um achado importante na doença de Kawasaki em países onde a vacina é aplicada de forma rotineira e pode ser um marcador útil para o diagnóstico precoce da doença de Kawasaki, principalmente em sua forma incompleta.

Characterisation of alternative expression vectors for recombinant Bacillus Calmette-Guérin as live bacterial delivery systems

BACKGROUND Bacillus Calmette-Guérin (BCG) is considered a promising live bacterial delivery system. However, several proposals for rBCG vaccines have not progressed, mainly due to the limitations of the available expression systems. OBJECTIVES To obtain a set of mycobacterial vectors using a range of promoters with different strengths based on a standard backbone, previously shown to be stable. METHODS Mycobacterial expression vectors based on the pLA71 vector as backbone, were obtained inserting different promoters (PAN, PαAg, PHsp60, PBlaF* and PL5) and the green fluorescence protein (GFP) as reporter gene, to evaluate features such as their relative strengths, and the in vitro (inside macrophages) and in vivo stability. FINDINGS The relative fluorescence observed with the different vectors showed increasing strength of the promoters: PAN was the weakest in both Mycobacterium smegmatis and BCG and PBlaF* was higher than PHsp60 in BCG. The relative fluorescence observed in a macrophage cell line showed that PBlaF* and PHsp60 were comparable. It was not possible to obtain strains transformed with the extrachromosomal expression vector containing the PL5 in either species. MAIN CONCLUSION We have obtained a set of potentially stable mycobacterial vectors with a arrange of expression levels, to be used in the development of rBCG vaccines.

Impact of Bacille Calmette-Guérin revaccination on serum IgE levels in a randomized controlled trial

Abstract INTRODUCTION: Bacille Calmette-Guérin (BCG) downmodulates allergen-specific IgE levels and prevents other atopic responses in experimental models but fails to protect against respiratory allergies. Human responsiveness to BCG is variable and may interfere with protection. METHODS: Multivariate models were evaluated to test the possible effect of responsiveness (assessed by IFN-γ production) to BCG revaccination on the modulation of total and allergen-specific serum IgE levels in healthy volunteers participating in a randomized controlled trial. RESULTS: Serum total or Derp-specific IgE levels did not change regardless of the increase in IFN-γ levels. CONCLUSIONS: BCG responsiveness does not affect protection against atopy.

Stable expression of Mycobacterium bovis antigen 85B in auxotrophic M. bovis bacillus Calmette-Guérin

BACKGROUND Bovine tuberculosis (TB) is a zoonotic disease caused by Mycobacterium bovis, responsible for causing major losses in livestock. A cost effective alternative to control the disease could be herd vaccination. The bacillus Calmette-Guérin (BCG) vaccine has a limited efficacy against bovine TB, but can improved by over-expression of protective antigens. The M. bovis antigen 85B demonstrates ability to induce protective immune response against bovine TB in animal models. However, current systems for the construction of recombinant BCG expressing multiple copies of the gene result in strains of low genetic stability that rapidly lose the plasmid in vivo. Employing antibiotic resistance as selective markers, these systems also compromise vaccine safety. We previously reported the construction of a stable BCG expression system using auxotrophic complementation as a selectable marker. OBJECTIVES The fundamental aim of this study was to construct strains of M. bovis BCG Pasteur and the auxotrophic M. bovis BCG ΔleuD expressing Ag85B and determine their stability in vivo. METHODS Employing the auxotrophic system, we constructed rBCG strains that expressed M. bovis Ag85B and compared their stability with a conventional BCG strain in mice. Stability was measured in terms of bacterial growth on the selective medium and retention of antigen expression. FINDINGS The auxotrophic complementation system was highly stable after 18 weeks, even during in vivo growth, as the selective pressure and expression of antigen were maintained comparing to the conventional vector. MAIN CONCLUSION The Ag85B continuous expression within the host may generate a stronger and long-lasting immune response compared to conventional systems.

The mc2-CMX vaccine induces an enhanced immune response against Mycobacterium tuberculosis compared to Bacillus Calmette-Guérin but with similar lung inflammatory effects

Although the attenuated Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccine has been used since 1921, tuberculosis (TB) control still proceeds at a slow pace. The main reason is the variable efficacy of BCG protection against TB among adults, which ranges from 0-80%. Subsequently, the mc2-CMX vaccine was developed with promising results. Nonetheless, this recombinant vaccine needs to be compared to the standard BCG vaccine. The objective of this study was to evaluate the immune response induced by mc2-CMX and compare it to the response generated by BCG. BALB/c mice were immunised with both vaccines and challenged withMycobacterium tuberculosis (Mtb). The immune and inflammatory responses were evaluated by ELISA, flow cytometry, and histopathology. Mice vaccinated with mc2-CMX and challenged with Mtb induced an increase in the IgG1 and IgG2 levels against CMX as well as recalled specific CD4+ T-cells that produced T-helper 1 cytokines in the lungs and spleen compared with BCG vaccinated and challenged mice. Both vaccines reduced the lung inflammatory pathology induced by the Mtb infection. The mc2-CMX vaccine induces a humoral and cellular response that is superior to BCG and is efficiently recalled after challenge with Mtb, although both vaccines induced similar inflammatory reductions.

Risk-benefit assessment of Bacillus Calmette-Guérin vaccination, anti-phenolic glycolipid I serology, and Mitsuda test response: 10-year follow-up of household contacts of leprosy patients

Abstract: INTRODUCTION: Despite multidrug therapy, leprosy remains a public health issue. The intradermal Bacillus Calmette-Guérin (BCG) vaccine, Mitsuda test (lepromin skin test), and anti-phenolic glycolipid I (PGL-I) serology are widely used in leprosy studies and have shown great epidemiological value. METHODS: This longitudinal study evaluated the relative risks and benefits of these three tools by comparing results observed in household contacts (HHCs) of leprosy patients who developed leprosy with those of HHCs who did not in a population of 2,992 individuals monitored during a 10-year period. RESULTS : Seventy-five (2.5%) new leprosy cases were diagnosed, including 28 (0.9%) co-prevalent cases. Therefore, for the risk-benefit assessment, 47 (1.6%) HHCs were considered as truly diagnosed during follow-up. The comparison between healthy and affected contacts demonstrated that not only did BCG vaccination increase protection, but boosters also increased to 95% relative risk (RR) reduction when results for having two or more scars were compared with having no scars [RR, 0.0459; 95% confidence interval (CI), 0.006-0.338]. Similarly, Mitsuda reactions >7mm in induration presented 7-fold greater protection against disease development compared to reactions of 0-3mm (RR, 0.1446; 95% CI, 0.0566-0.3696). In contrast, anti-PGL-I ELISA seropositivity indicated a 5-fold RR increase for disease outcome (RR, 5.688; 95% CI, 3.2412-9.9824). The combined effect of no BCG scars, Mitsuda reaction of <7mm, and seropositivity to anti-PGL-I increased the risk for leprosy onset 8-fold (RR, 8.109; 95% CI, 5.1167-12.8511). CONCLUSIONS: The adoption of these combined assays may impose measures for leprosy control strategies.

Oral bacillus Calmette-Guérin vaccine against tuberculosis: why not?

The bacillus Calmette-Guérin (BCG) vaccine is the only licensed vaccine for human use against tuberculosis (TB). Although controversy exists about its efficacy, the BCG vaccine is able to protect newborns and children against disseminated forms of TB, but fails to protect adults against active forms of TB. In the last few years, interest in the mucosal delivery route for the vaccine has been increasing owing to its increased capacity to induce protective immune responses both in the mucosal and the systemic immune compartments. Here, we show the importance of this route of vaccination in newly developed vaccines, especially for vaccines against TB.

Active search for leprosy cases in Midwestern Brazil: a serological evaluation of asymptomatic household contacts before and after prophylaxis with bacillus Calmette-Guérin / Busca ativa por casos de hanseníase no Centro-Oeste do Brasil: avaliação sorológica dos contatos domiciliares assintomáticos antes e após a profilaxia com Bacillus Calmette-Guérin

Leprosy is a disease caused by Mycobacterium leprae that carries a high risk of disability, making early diagnosis mandatory. This study aimed to determine the applicability of anti-PGL-1 IgM antibody detection, using the ML FLOW technique, as an assistant tool for the detection of leprosy infection in asymptomatic household contacts (AHHC) of multibacillary leprosy index cases from Midwest Brazil. Serological changes induced by the prophylaxis of these household contacts with Bacillus Calmette-Guérin (BCG) were also verified. A total of 91 AHHC were assessed, among which, 18.68% (n = 17) presented both positive bacilloscopy and positive anti-PGL-1 IgM serology. Positivity concordance between these two laboratorial exams (Kappa Index = 1; p < 0.001) was indicated, however, one case did not demonstrate concordance between the semiquantitative assessment of anti-PGL-1 IgM and the bacilloscopy index (Kappa Index = 0.96; p < 0.001). Among the 17 AHHC with positive bacilloscopy, eight were reassessed after prophylaxis with BCG and two of them presented negative anti-PGL-1 IgM serology, being these patients who had presented a bacilloscopy index of < 2[+] in the initial assessment. This study shows that anti-PGL-1 IgM detection may be used as a tool to determine the bacillary load in AHHC and to detect immune changes related to prophylaxis by nonspecific vaccination.

A hanseníase é doença causada pelo Mycobacterium leprae, apresentando elevado potencial incapacitante, o que torna indispensável seu diagnóstico precoce. O estudo visa determinar a aplicabilidade da detecção de anticorpos anti-PGL1-IgM por meio da técnica do ML FLOW como ferramenta adjuvante ao diagnóstico de hanseníase em contatos domiciliares assintomáticos (AHHC) de pacientes multibacilares procedentes da região Centro-Oeste do Brasil, bem como, documentar o comportamento sorológico após a profilaxia com a vacina Bacillus Calmette-Guérin (BCG). Foram avaliados 91 AHHC atendidos no Hospital Universitário de Brasília - Brasil, dos quais 18,68% (n = 17) apresentaram positividade para baciloscopia e anti-PGL1-IgM, totalizando uma concordância completa entre os dois grupos (Índice Kappa = 1; p < 0,001). Em apenas um dos casos não observou-se concordância entre a avaliação semi-quantitativa do anti-PGL1-IgM e índice baciloscópico (Índice Kappa = 0,96; p < 0,001). Oito dos 17 AHHC com baciloscopia positiva foram reavaliados após profilaxia com BCG e apenas dois apresentaram negativação dos títulos anti-PGL1-IgM, sendo tais casos correspondentes aos que haviam apresentado índice baciloscópico menor do que 2[+] na avaliação inicial. O estudo corrobora o potencial do anti-PGL1-IgM como ferramenta de predição da carga bacilar em AHHC da região Centro-Oeste do Brasil, e surpreende alterações imunes relacionadas à profilaxia obtida pela vacinação não específica com BCG.

Rational design of diagnostic and vaccination strategies for tuberculosis

The development of diagnostic tests which can readily differentiate between vaccinated and tuberculosis-infected individuals is crucial for the wider utilization of bacillus Calmette-Guérin (BCG) as vaccine in humans and animals. BCG_0092 is an antigen that elicits specific delayed type hypersensitivity reactions similar in size and morphological aspects to that elicited by purified protein derivative, in both animals and humans infected with the tubercle bacilli. We carried out bioinformatics analyses of the BCG_0092 and designed a diagnostic test by using the predicted MHC class I epitopes. In addition, we performed a knockout of this gene by homologous recombination in the BCG vaccine strain to allow differentiation of vaccinated from infected individuals. For that, the flanking sequences of the target gene (BCG_0092)were cloned into a suicide vector. Spontaneous double crossovers, which result in wild type revertants or knockouts were selected using SacB. BCG_0092 is present only in members of the Mycobacterium tuberculosis complex. Eight predicted MHC class I epitopes with potential for immunological diagnosis were defined, allowing the design of a specific diagnostic test. The strategy used to delete the (BCG_0092) gene from BCG was successful. The knockout genotype was confirmed by PCR and by Southern blot. The mutant BCG strain has the potential of inducing protection against tuberculosis without interfering with the diagnostic test based on the use of selected epitopes from BCG_0092.

Ausência de efeito da memória imunológica e antígenos micobacterianos sobre a produção de IgE e citocinas em resposta a Dermatophagoides pteronyssinus / No effect of mycobacterial antigens and immunological memory on the production of cytokines and IgE in response to Dermatophagoides pteronyssinus

Introdução: As doenças respiratórias alérgicas, tais como rinite e asma, afetam elevada proporção da população brasileira. Estima-se que mais de 58 mil pessoas foram afetadas por alguma destas condições no Brasil em 2002-2003. Estudos realizados em humanos e animais sugerem que a exposição ambiental ao Mycobacterium tuberculosis ou imunização com o M. bovis (vacina BCG), podem estar relacionadas à proteção contra doenças alérgicas. Objetivo: Investigar a influência da resposta Th1 a antígenos micobacterianos sobre a modulação da resposta do tipo Th2 ao ácaro Dermatophagoides pteronyssinus (Derp). Métodos: O estudo compreendeu duas fases. Para avaliar o efeito da resposta à revacinação com o BCG sobre a modulação de uma resposta do tipo Th2 ao Derp, foi realizado um estudo de intervenção randomizado com coorte prospectiva, e os voluntários que participaram compuseram a Amostra 1. Para avaliar o efeito da resposta à infecção latente com M. tuberculosis sobre a modulação de uma resposta do tipo Th2 ao Derp, foi feito um estudo de caso-controle e os voluntários que participaram compuseram a Amostra 2. A população foi composta por adultos jovens com idade entre 19 a 33 anos. Todos responderam ao questionáro ISAAC...

Introduction: Allergic respiratory diseases such as asthma and rhinitis, affecting a high proportion of the Brazilian population. More than 58.000 people have been affected by some of these conditions in Brazil in 2002-2003. Studies in humans and animals suggest that environmental exposure to Mycobacterium tuberculosis or immunization with Mycobacterium bovis (BCG), may be related to protection against allergic diseases. Objective: To investigate the influence of Th1 response to mycobacterial antigens on the modulation of Th2-type response to aeroallergen Dermatophagoides pteronyssinus (Derp). Methods: The study comprised two phases. To evaluate the effect of the response to revaccination with BCG on the modulation of a Th2-type response to Derp, we conducted a randomized intervention study with prospective cohort, and the volunteers composed the Sample 1. To evaluate the effect of latent response to infection with M. tuberculosis on the modulation of a Th2-type response to Derp, a study was made of case-control and the volunteers composed the Sample 2. The population consisted of young adults aged 19 to 33 years. All responded to questionnaire ISAAC...

Co-Immunization of Plasmid DNA Encoding IL-12 and IL-18 with Bacillus Calmette-Guerin Vaccine against Progressive Tuberculosis

PURPOSE: Bacillus Calmette-Guerin (BCG) vaccine has widely been used to immunize against tuberculosis, but its protective efficacy is variable in adult pulmonary tuberculosis, while it is not efficiently protective against progressive infection of virulent Mycobacterium tuberculosis strains. In this study, the protective effects of plasmid DNA vaccine constructs encoding IL-12 or IL-18 with the BCG vaccine were evaluated against progressive infection of M. tuberculosis, using mouse aerosol challenge model. MATERIALS AND METHODS: Plasmid DNA vaccine constructs encoding IL-12 or IL-18 were constructed and mice were immunized with the BCG vaccine or with IL-12 DNA or IL-18 DNA vaccine constructs together with the BCG vaccine. RESULTS: The BCG vaccine induced high level of interferon gamma (IFN-gamma) but co-immunization of IL-12 or IL-18 DNA vaccine constructs with the BCG vaccine induced significantly higher level of IFN-gamma than a single BCG vaccine. The BCG vaccine was highly protective at early stage of M. tuberculosis infection, but its protective efficacy was reduced at later stage of infection. The co-immunization of IL-12 DNA vaccine constructs with the BCG vaccine was slightly more protective at early stage of infection and was significantly more protective at later stage infection than a single BCG vaccine. CONCLUSION: Co-immunization of IL-12 DNA vaccine with the BCG vaccine induced more protective immunity and was more effective for protection against progressive infection of M. tuberculosis.

Leukotrienes are not essential for the efficacy of a heterologous vaccine against Mycobacterium tuberculosis infection

Leukotrienes are reported to be potent proinflammatory mediators that play a role in the development of several inflammatory diseases such as asthma, rheumatoid arthritis and periodontal disease. Leukotrienes have also been associated with protection against infectious diseases. However, the role of leukotrienes in Mycobacterium tuberculosis infection is not understood. To answer this question, we studied the role of leukotrienes in the protective immune response conferred by prime-boost heterologous immunization against tuberculosis. We immunized BALB/c mice (4-11/group) with subcutaneous BCG vaccine (1 x 10(5) M. bovis BCG) (prime) followed by intramuscular DNA-HSP65 vaccine (100 µg) (boost). During the 30 days following the challenge, the animals were treated by gavage daily with MK-886 (5 mg·kg-1·day-1) to inhibit leukotriene synthesis. We showed that MK-886-treated mice were more susceptible to M. tuberculosis infection by counting the number of M. tuberculosis colony-forming units in lungs. The histopathological analysis showed an impaired influx of leukocytes to the lungs of MK-886-treated mice after infection, confirming the involvement of leukotrienes in the protective immune response against experimental tuberculosis. However, prime-boost-immunized mice treated with MK-886 remained protected after challenge with M. tuberculosis, suggesting that leukotrienes are not required for the protective effect elicited by immunization. Protection against M. tuberculosis challenge achieved by prime-boost immunization in the absence of leukotrienes was accompanied by an increase in IL-17 production in the lungs of these animals, as measured by ELISA. Therefore, these data suggest that the production of IL-17 in MK-886-treated, immunized mice could contribute to the generation of a protective immune response after infection with M. tuberculosis.

Preparation of a working seed lot of BCG and quality control by PCR genotyping / Preparación de un lote semilla de trabajo de BCG y control de calidad por genotipificación por PCR

The bacillus Calmette-Guérin (BCG) was obtained in 1920 after successive passages leading to the attenuation of a Mycobacterium bovis strain. For the following 40 years, BCG had been replicated, resulting in substrains with genotypic and phenotypic differences. Several genomic studies have compared two BCG strains, M. bovis and Mycobacterium tuberculosis, and observed that deleted regions in the different strains could be related to differences in antigenic properties. In this work, a working seed lot was obtained from a lyophilized secondary seed lot from the BCG Pasteur strain 1173 P2 and genetically characterized. The genome was analyzed by PCR directed to five regions (RD1, RD2, RD14, RD15, DU2), using the seed lot and different available strains as templates. No genetic differences were found in the fragments studied as compared to the Pasteur strain. A total of 20 passages were carried out and no differences were found in the size of the fragments amplified by PCR. In conclusion, this method allows to control a working seed lot genotypically and to assess the stability of the BCG genome.

El bacilo de Calmette-Guérin (BCG) se obtuvo en 1920, después de sucesivos pasajes que llevaron a la atenuación de una cepa de Mycobacterium bovis. A lo largo de los 40 años subsiguientes la cepa BCG fue replicada y surgieron subcepas con diferencias fenotípicas y genotípicas. Se realizaron varios estudios de comparación genómica de diferentes cepas de BCG, M. bovis y Mycobacterium tuberculosis, y se observó que las deleciones de regiones en las diferentes cepas podrían estar relacionadas con diferencias en las propiedades antigénicas. En este trabajo se describe la preparación y caracterización genética de un lote semilla de trabajo obtenido a partir de un lote semilla secundaria liofilizado de la cepa BCG Pasteur 1173 P2. Se analizaron por PCR cinco regiones (RD1, RD2, RD14, RD15, DU2) en el lote semilla de trabajo utilizando como control las diferentes cepas disponibles. No se hallaron diferencias genéticas en los fragmentos estudiados al comparar el lote semilla de trabajo con la cepa BCG Pasteur 1173 P2. Asimismo, se efectuaron hasta 20 pasajes y no se encontraron diferencias en el tamaño de los fragmentos amplificados por PCR. En conclusión, se ha puesto a punto un método que permite controlar el genotipo de un lote semilla de trabajo y evaluar la estabilidad del genoma del BCG.

Stable expression of Leptospira interrogans antigens in auxotrophic Mycobacterium bovis BCG

Mycobacterium bovis BCG has been proposed as an effective live vector for multivalent vaccines. The development of mycobacterial genetic systems to express foreign antigens and the adjuvanticity of BCG are the basis for the potential use of this attenuated mycobacterium as a recombinant vaccine vector. Stable plasmid vectors without antibiotic resistance markers are needed for heterologous antigen expression in BCG. Our group recently described the construction of a BCG expression system using auxotrophic complementation as a selectable marker. In this work, LipL32 and LigAni antigens of Leptospira interrogans were cloned and expressed in M. bovis BCG Pasteur and in the auxotrophic M. bovis BCG ΔleuD strains under the control of the M. leprae 18kDa promoter. Stability of the plasmids during in vitro growth and after inoculation of the recombinant BCG strains in hamsters was compared. The auxotrophic complementation system was highly stable, even during in vivo growth, as the selective pressure was maintained, whereas the conventional vector was unstable in the absence of selective pressure. These results confirm the usefulness of the new expression system, which represents a huge improvement over previously described expression systems for the development of BCG into an effective vaccine vector.

¿Es suficiente la prueba tuberculínica para el diagnóstico de la infección tuberculosa? / Is the tuberculin skin test still suitable to diagnose tuberculosis infection?

La infección tuberculosa (TB) se determina por la prueba tuberculínica (PTC) con PPD, un extracto de proteínas/péptidos de Mycobacterium tuberculosis, algunos compartidos con otras micobacterias como BCG, lo cual origina falsos resultados positivos en vacunados/no infectados. La nuevas pruebas ex vivo miden el interferón ? (IFN- ?) liberado en sangre, o la cantidad de células que lo producen, en presencia de los péptidos ESAT-6 y CFP-10 de M. tuberculosis. Como estos antígenos no existirían en BCG, las pruebas IFN-? diferenciarían infección TB de vacunación. Numerosos estudios han comparado estas pruebas con la PTC con resultados aún no concluyentes. Las pruebas IFN-? tendrían menor sensibilidad que la PTC, aunque su menor positividad en poblaciones vacunadas podría interpretarse como mayor especificidad. Por otra parte, la vacunación BCG, si no es reciente, no es causa de falsos positivos a la PTC: reacciones =10 mm o =15 mm indican infección TB con altísima probabilidad. Donde la incidencia de TB es mediana o alta, la PTC aventaja en costo-eficiencia a las pruebas IFN-?, siempre que se emplee PPD de calidad garantizada, disponible en todos los centros de salud del país, con aplicación, lectura e interpretación estandarizadas. Como existen en la Argentina problemas de abastecimiento de PPD importado, es preciso producirlo localmente y asegurar su control de calidad. También es necesaria la investigación aplicada al desarrollo de nuevos métodos y la evaluación de su capacidad de predecir la evolución de infección a TB activa, es decir, de identificar las personas que más se beneficiarían con quimioprofilaxis.

Tuberculosis (TB) infection is currently being diagnosed by the tuberculin skin test (TST) with PPD. Some Mycobacterium tuberculosis PPD components are present in BCG, which can be the cause of false positive TST results in BCG vaccinated persons. New IFN-? release assays (IGRAs) are based on the ex vivo release of IFN-? by peripheral blood cells in presence of M. tuberculosis antigens ESAT-6 and CFP-10, which should be absent in BCG. These assays consist in either quantifying released IFN-? or enumerating IFN-? producing cells. In principle, IGRAs should differentiate true TB infection from vaccination and results of several studies suggest that these assays display lower positivity than TST. Whether the lower positivity could be attributed to higher specificity or to lower sensitivity as compared with PPD is still unclear. BCG vaccination, if not recently applied, cannot be blamed for false positive TST reactions. Strong TST reactions (=10 mm or =15 mm) are highly correlated with TB infection. In settings where TB continues being a serious health problem, cost-effectiveness evaluations would privilege TST under certain conditions: supply of quality-assured PPD reagent, standardized criteria for TST application, reading and interpretation, and regular availability in health centers countrywide. In view of current limitations in the supply of imported PPD in Argentina, its production/quality assurance should be considered a public health priority. Still, key questions remain to be addressed concerning the role of IGRAs and TST in predicting risk of TB disease, in other words, in identifying persons who will benefit most from chemoprophylaxis.

Prevalence of tuberculous infection among school children in Kerala.

BACKGROUND: There is paucity of information on epidemiological situation of Tuberculosis (TB) in the State of Kerala. The DOTS strategy under the Revised National Tuberculosis Control Programme (RNTCP) was introduced in the year 1998 to cover the entire State by 2002. OBJECTIVE: To estimate the prevalence of tuberculous infection among children attending 1-4th standard in a sample of selected schools in Kerala. METHODS: A cluster-sample school-based tuberculin survey was carried out in 70 schools selected by a two-stage sampling procedure. A total of 4821 children (including those with and without BCG scar) in the age group of 5-9 years were tuberculin tested using 1 TU PPD RT23 with Tween 80 and the maximum transverse diameter of induration was measured about 72 hours later. About 81% of the children were found to have BCG scars. Analysis was also undertaken by mixture model. RESULTS: While 67% of children without BCG scar and 62% with scar did not elicit any induration at the test site, the mode or anti-mode of reactions due to infection with tubercle bacilli could not be identified from the distribution graphs. Analysis by mixture model also did not provide the best fit thus precluding estimation of prevalence of infection. About 5% of children had reactions > or =10 mm, 3% had reactions > or =12 mm and 2% had reactions > or =14 mm. CONCLUSION: Low proportion of reactors indicated a low level of transmission of infection in Kerala. Considering the problems in interpretation of tuberculin survey data, it may not be feasible to use ARTI as an epidemiological parameter to monitor future trends of TB situation in the state.

Factors associated with treatment failure in childhood tuberculosis.

We retrospectively reviewed records of 541 children (315 boys) suffering from tuberculosis, median age 95 (range 2-180) months, to determine factors associated with treatment failure. 256 (47.3%) children had pulmonary tuberculosis (PTB) while 285 (52.7%) had extrapulmonary tuberculosis (EPTB). 459 (84.8%) children were cured and 82 (15.5%) had treatment failure. On bivariate analysis, AFB positivity [OR= 2.13 (95% CI 1.18- 3.85)], non-receipt of BCG vaccination during infancy [OR=1.73 (1.02- 2.91)] and EPTB [1.9 (1.16- 3.11)] were associated with treatment failure. On multivariate analysis, only extrapulmonary tuberculosis was significantly associated with treatment failure.

Bacille Calmette-Guérin lymphadenitis and immune reconstitution syndrome in HIV-infected children on antiretroviral therapy in Jamaica / Linfadenitis por Calmette-Guérin y síndrome de reconstitución inmune en niños infectados con el VIH bajo terapia antiretroviral en Jamaica

The immune reconstitution inflammatory syndrome (IRIS) is a recognized complication associated with opportunistic infections occurring in HIV-infected individuals after the initiation of highly active antiretroviral therapy (HAART). We report on three HIV-infected infants with rapid progressor HIV disease who present with IRIS due to the BCG vaccine and occurring 3-6 weeks after initiation of HAART.

El síndrome inflamatorio de la reconstitución inmune (SIRI) es una complicación reconocida asociada con infecciones oportunistas que ocurren en individuos infectados por el VIH, luego de su iniciación en la terapia antiretroviral altamente activa (TARAA). Se reporta el caso de tres infantes infectados por VIH con enfermedad VIH de progresión rápida, que se presentan con SIRI debido a la vacuna BCG, 3-6 semanas después de la iniciación de TARAA.