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PURPOSE: Music and memory are inextricably linked, and the recollection of music varies according to age. In order to create personalized music playlists tailored for people living with dementia, this study aimed to determine the age at which healthy individuals could best recall music that was popular at the time. METHODS: A survey was designed asking participants to identify the number of songs they recalled from a random selection of 10 from the 100 most popular songs from each year, presented in random order of years, from 1945 to 2015. Of the 311 individuals born between 1929 and 2002, who responded to the survey, 157 met the inclusion criteria. RESULTS: The median peak of recollection was between the ages of 13 and 19 across all age-cohorts, with participants recalling a maximum median number of 6-8 songs in all of the age-cohorts. There was no evidence of a difference in the peak age of recollection between those who recognized seven or more songs in at least 1 year and those who recognized fewer than seven songs in all years. CONCLUSION: The peak of recollection of popular music occurs in the teenage years, regardless of era of birth. Music from this "reminiscence bump" provides a rich source of retained music that should be tapped when creating playlists of meaningful music for people living with dementia.
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Randomized clinical trials are the most reliable approaches to evaluating the effects of new treatments and vaccines. During the 2014-2015 West African Ebola epidemic, many argued that such trials were neither ethical nor feasible in an environment of limited health infrastructure and severe disease with a high fatality rate. Consensus among the numerous organizations providing help to the affected areas was never achieved, resulting in fragmented collaboration, delayed study initiation, and ultimately failure to provide definitive evidence on the efficacy of treatments and vaccines. Randomized trials were in fact approved by local ethics boards and initiated, demonstrating that randomized trials, even in such difficult circumstances, are feasible. Improved planning and collaboration among research and humanitarian organizations, and affected communities, in the interepidemic periods are needed to ensure that questions regarding the efficacy of vaccines and treatments can be definitively answered during future public health emergencies.
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Brotes de Enfermedades , Urgencias Médicas , Ética en Investigación , Salud Pública , Ensayos Clínicos Controlados Aleatorios como Asunto/normas , Proyectos de Investigación/normas , África Occidental/epidemiología , Grupos Control , Fiebre Hemorrágica Ebola/tratamiento farmacológico , Fiebre Hemorrágica Ebola/epidemiología , HumanosRESUMEN
BACKGROUND: To increase access to antiretroviral therapy in resource-limited settings, several experts recommend "task shifting" from doctors to clinical officers, nurses and midwives. This study sought to identify task shifting that has already occurred and assess the antiretroviral therapy training needs among clinicians to whom tasks have shifted. METHODS: The Infectious Diseases Institute, in collaboration with the Ugandan Ministry of Health, surveyed health professionals and heads of antiretroviral therapy clinics at a stratified random sample of 44 health facilities accredited to provide this therapy. A sample of 265 doctors, clinical officers, nurses and midwives reported on tasks they performed, previous human immunodeficiency virus training, and self-assessment of knowledge of human immunodeficiency virus and antiretroviral therapy. Heads of the antiretroviral therapy clinics reported on clinic characteristics. RESULTS: Thirty of 33 doctors (91%), 24 of 40 clinical officers (60%), 16 of 114 nurses (14%) and 13 of 54 midwives (24%) who worked in accredited antiretroviral therapy clinics reported that they prescribed this therapy (p<0.001). Sixty-four percent of the people who prescribed antiretroviral therapy were not doctors. Among professionals who prescribed it, 76% of doctors, 62% of clinical officers, 62% of nurses and 51% of midwives were trained in initiating patients on antiretroviral therapy (p=0.457); 73%, 46%, 50% and 23%, respectively, were trained in monitoring patients on the therapy (p=0.017). Seven percent of doctors, 42% of clinical officers, 35% of nurses and 77% of midwives assessed that their overall knowledge of antiretroviral therapy was lower than good (p=0.001). CONCLUSION: Training initiatives should be an integral part of the support for task shifting and ensure that antiretroviral therapy is used correctly and that toxicity or drug resistance do not reverse accomplishments to date.
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BACKGROUND: There is considerable variability in the outcome of Mycobacterium tuberculosis infection. We hypothesized that Mycobacterium africanum was less likely than M. tuberculosis to transmit and progress to tuberculosis disease. METHODS: In a cohort study of patients with tuberculosis and their household contacts in The Gambia, we categorized 1808 HIV-negative tuberculosis contacts according to exposure to M. tuberculosis or M. africanum. Positive skin test results indicated transmission, and development of tuberculosis during 2 years of follow-up indicated progression to disease. RESULTS: Transmission rates were similar, but rates of progression to disease were significantly lower in contacts exposed to M. africanum than in those exposed to M. tuberculosis (1.0% vs. 2.9%; hazard ratio [HR], 3.1 [95% confidence interval {CI}, 1.1-8.7]). Within M. tuberculosis sensu stricto, contacts exposed to a Beijing family strain were most likely to progress to disease (5.6%; HR relative to M. africanum, 6.7 [95% CI, 2.0-22]). CONCLUSIONS: M. africanum and M. tuberculosis transmit equally well to household contacts, but contacts exposed to M. africanum are less likely to progress to tuberculosis disease than those exposed to M. tuberculosis. The variable rate of progression by lineage suggests that tuberculosis variability matters in clinical settings and should be accounted for in studies evaluating tuberculosis vaccines and treatment regimens for latent tuberculosis infection.
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Mycobacterium tuberculosis/patogenicidad , Mycobacterium/patogenicidad , Tuberculosis/transmisión , Adolescente , Adulto , Anciano , Antígenos Bacterianos/análisis , Proteínas Bacterianas/análisis , Niño , Preescolar , Estudios de Cohortes , Progresión de la Enfermedad , Femenino , Estudios de Seguimiento , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Especificidad de la Especie , Tuberculosis/microbiologíaRESUMEN
RATIONALE: Tuberculosis remains a major cause of morbidity and mortality in the developing world. A better understanding of the mechanisms of disease protection could allow novel strategies to disease management and control. OBJECTIVES: To identify human genomic loci with evidence of linkage to tuberculosis susceptibility and, within these loci, to identify individual genes influencing tuberculosis susceptibility. METHODS: Affected sibling pair analysis in South African and Malawian populations. Independent case-control study in West Africa. MEASUREMENTS AND MAIN RESULTS: Two novel putative loci for tuberculosis susceptibility are identified: chromosome 6p21-q23 and chromosome 20q13.31-33--the latter with the strongest evidence for any locus reported to date in human tuberculosis (single point LOD score of 3.1, P = 10(-4), with a maximum likelihood score [MLS] of 2.8). An independent, multistage genetic association study in West African populations mapped this latter region in detail, finding evidence that variation in the melanocortin 3 receptor (MC3R) and cathepsin Z (CTSZ) genes play a role in the pathogenesis of tuberculosis. CONCLUSIONS: These results demonstrate how a genomewide approach to the complex phenotype of human tuberculosis can identify novel targets for further research.
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Catepsinas/genética , Polimorfismo Genético , Receptor de Melanocortina Tipo 3/genética , Tuberculosis Pulmonar/etnología , Tuberculosis Pulmonar/genética , África Occidental/epidemiología , Población Negra/genética , Estudios de Casos y Controles , Catepsina K , Catepsina Z , Ligamiento Genético , Predisposición Genética a la Enfermedad/etnología , Predisposición Genética a la Enfermedad/genética , Humanos , Funciones de Verosimilitud , Malaui/epidemiología , Repeticiones de Microsatélite , Linaje , Análisis de Regresión , Hermanos , Sudáfrica/epidemiologíaRESUMEN
BACKGROUND: Studies of Tuberculosis (TB) case contacts are increasingly being utilised for understanding the relationship between M. tuberculosis and the human host and for assessing new interventions and diagnostic tests. We aimed to identify the incidence rate of new TB cases among TB contacts and to relate this to their initial Mantoux and ELISPOT test results. METHODS AND FINDINGS: After initial Mantoux and ELISPOT tests and exclusion of co-prevalent TB cases, we followed 2348 household contacts of sputum smear positive TB cases. We visited them at 3 months, 6 months, 12 months, 18 months and 24 months, and investigated those with symptoms consistent with TB. Those who were diagnosed separately at a government clinic had a chest x-ray. Twenty six contacts were diagnosed with definite TB over 4312 person years of follow-up (Incidence rate 603/100,000 person years; 95% Confidence Interval, 370-830). Nine index and secondary case pairs had cultured isolates available for genotyping. Of these, 6 pairs were concordant and 3 were discordant. 2.5% of non-progressors were HIV positive compared to 12% of progressors (HR 6.2; 95% CI 1.7-22.5; p = 0.010). 25 secondary cases had initial Mantoux results, 14 (56%) were positive ; 21 had initial ELISPOT results, 11 (52%) were positive; 15 (71%) of 21 tested were positive by one or the other test. Of the 6 contacts who had concordant isolates with their respective index case, 4 (67%) were Mantoux positive at recruitment, 3 (50%) were ELISPOT positive; 5 (83%) were positive by one or other of the two tests. ELISPOT positive contacts, and those with discordant results, had a similar rate of progression to those who were Mantoux positive. Those negative on either or both tests had the lowest rate of progression. CONCLUSIONS: The incidence rate of TB disease in Gambian TB case contacts, after screening for co-prevalent cases, was 603/100,000 person years. Since initial ELISPOT test and Mantoux tests were each positive in only just over half of cases, but 71% were positive by one or other test, positivity by either might be the best indication for preventive treatment. These data do not support the replacement of the Mantoux test by an ELISPOT test in The Gambia or similar settings.
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Ensayo de Inmunoadsorción Enzimática/métodos , Pruebas Cutáneas/métodos , Tuberculosis/epidemiología , Gambia/epidemiología , Humanos , Incidencia , Valor Predictivo de las Pruebas , Tuberculosis/diagnósticoRESUMEN
BACKGROUND: Tuberculosis causes significant morbidity and mortality worldwide, especially in sub-Saharan Africa. DC-SIGN, encoded by CD209, is a receptor capable of binding and internalizing Mycobacterium tuberculosis. Previous studies have reported that the CD209 promoter single nucleotide polymorphism (SNP)-336A/G exerts an effect on CD209 expression and is associated with human susceptibility to dengue, HIV-1 and tuberculosis in humans. The present study investigates the role of the CD209 -336A/G variant in susceptibility to tuberculosis in a large sample of individuals from sub-Saharan Africa. METHODS AND FINDINGS: A total of 2,176 individuals enrolled in tuberculosis case-control studies from four sub-Saharan Africa countries were genotyped for the CD209 -336A/G SNP (rs4804803). Significant overall protection against pulmonary tuberculosis was observed with the -336G allele when the study groups were combined (n = 914 controls vs. 1262 cases, Mantel-Haenszel 2 x 2 chi(2) = 7.47, P = 0.006, odds ratio = 0.86, 95%CI 0.77-0.96). In addition, the patients with -336GG were associated with a decreased risk of cavitory tuberculosis, a severe form of tuberculosis disease (n = 557, Pearson's 2x2 chi(2) = 17.34, P = 0.00003, odds ratio = 0.42, 95%CI 0.27-0.65). This direction of association is opposite to a previously observed result in a smaller study of susceptibility to tuberculosis in a South African Coloured population, but entirely in keeping with the previously observed protective effect of the -336G allele. CONCLUSION: This study finds that the CD209 -336G variant allele is associated with significant protection against tuberculosis in individuals from sub-Saharan Africa and, furthermore, cases with -336GG were significantly less likely to develop tuberculosis-induced lung cavitation. Previous in vitro work demonstrated that the promoter variant -336G allele causes down-regulation of CD209 mRNA expression. Our present work suggests that decreased levels of the DC-SIGN receptor may therefore be protective against both clinical tuberculosis in general and cavitory tuberculosis disease in particular. This is consistent with evidence that Mycobacteria can utilize DC-SIGN binding to suppress the protective pro-inflammatory immune response.
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Moléculas de Adhesión Celular/genética , Lectinas Tipo C/genética , Polimorfismo de Nucleótido Simple , Receptores de Superficie Celular/genética , Tuberculosis/genética , Alelos , Secuencia de Bases , Estudios de Casos y Controles , Cartilla de ADN , HumanosRESUMEN
This article describes immunological HIV progression, mortality, and its predictors in 974 Zambian adults. During 3138 person-years of follow-up, 281 deaths occurred, and the overall mortality rate was 9.0 per 100 person-years. Thirty-six percent of patients were dead within 5 years of enrollment. The median survival in patients with baseline CD4 count ≥500 cells/mm³ was 5.62 years, with CD4 count between 200 and 499 cells/mm³ 5.46 years, and with CD4 count <200 cells/mm³ 3.89 years. The mortality rate increased significantly with older age (6.9 in patients <25 years, 9.3 in individuals aged 25-39 years, 10.2 in patients ≥40 years) and was higher in women (rate ratio 1.29). The median annual change of progression markers was -29.6 cells/mm³ for CD4 count, -3.0% for CD4 count percentage, 1.2 nmol/L for neopterin, -1.9 g/L for hemoglobin, and -70 cells/mm³ for total lymphocyte count. Hemoglobin and neopterin were as accurate as CD4 count to predict mortality.
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Progresión de la Enfermedad , Infecciones por VIH/inmunología , Infecciones por VIH/mortalidad , Adulto , Distribución por Edad , Anemia/sangre , Biomarcadores , Recuento de Linfocito CD4 , Estudios de Cohortes , Femenino , Infecciones por VIH/diagnóstico , Humanos , Estimación de Kaplan-Meier , Masculino , Neopterin/sangre , Pronóstico , Distribución por Sexo , Zambia/epidemiologíaRESUMEN
BACKGROUND: Very little longitudinal information is available regarding the performance of T cell-based tests for Mycobacterium tuberculosis infection. To address this deficiency, we conducted a longitudinal assessment of the enzyme-linked immunosorbent spot test (ELISPOT) test in comparison to the standard tuberculin skin test (TST). METHODS AND FINDINGS: In tuberculosis (TB) contacts we repeated ELISPOT tests 3 mo (n = 341) and 18 mo (n = 210) after recruitment and TSTs at 18 mo (n = 130). We evaluated factors for association with conversion and reversion and investigated suspected cases of TB. Of 207 ELISPOT-negative contacts, 51 (24.6%) had 3-mo ELISPOT conversion, which was associated with a positive recruitment TST (odds ratio [OR] 2.2, 95% confidence interval [CI] 1.0-5.0, p = 0.048) and negatively associated with bacillus Calmette-Guérin (BCG) vaccination (OR 0.5, 95% CI 0.2-1.0, p = 0.06). Of 134 contacts, 54 (40.2%) underwent 3-mo ELISPOT reversion, which was less likely in those with a positive recruitment TST (OR 0.3, 95% CI 0.1-0.8, p = 0.014). Between 3 and 18 mo, 35/132 (26.5%) contacts underwent ELISPOT conversion and 28/78 (35.9%) underwent ELISPOT reversion. Of the 210 contacts with complete results, 73 (34.8%) were ELISPOT negative at all three time points; 36 (17.1%) were positive at all three time points. Between recruitment and 18 mo, 20 (27%) contacts had ELISPOT conversion; 37 (50%) had TST conversion, which was associated with a positive recruitment ELISPOT (OR 7.2, 95% CI 1.4-37.1, p = 0.019); 18 (32.7%) underwent ELISPOT reversion; and five (8.9%) underwent TST reversion. Results in 13 contacts diagnosed as having TB were mixed, but suggested higher TST sensitivity. CONCLUSIONS: Both ELISPOT conversion and reversion occur after M. tuberculosis exposure. Rapid ELISPOT reversion may reflect M. tuberculosis clearance or transition into dormancy and may contribute to the relatively low reported ELISPOT conversion rate. Therefore, a negative ELISPOT test for M. tuberculosis infection should be interpreted with caution.
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Ensayo de Inmunoadsorción Enzimática , Interferón gamma/análisis , Mycobacterium tuberculosis/aislamiento & purificación , Linfocitos T/metabolismo , Tuberculosis/diagnóstico , Adolescente , Adulto , Anciano , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Estudios de Cohortes , Trazado de Contacto , ADN Bacteriano/genética , Bases de Datos Factuales , Reacciones Falso Negativas , Femenino , Estudios de Seguimiento , Gambia/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/inmunología , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Esputo/microbiología , Linfocitos T/inmunología , Factores de Tiempo , Prueba de Tuberculina , Tuberculosis/epidemiología , Tuberculosis/inmunología , Tuberculosis/microbiologíaRESUMEN
Commercial tests measuring IFN-gamma responses to ESAT-6 and CFP-10 are available for diagnosing Mycobacterium tuberculosis infection. Measures that minimize cost and complexity will facilitate their application in less-developed countries. We investigated whether overlapping peptides representing both ESAT-6 and CFP-10 are required to detect M. tuberculosis infection in a high TB-burden country, and whether they can be combined in a single pool. ESAT-6 and CFP-10 peptides were compared in IFN-gamma enzyme-linked immunospot (ELISPOT) in 183 HIV-negative smear-positive TB cases and 1673 HIV-negative household contacts. Separate peptide pools for each antigen were compared with a combined pool in 498 contacts. Forty per cent of responsive contacts recognized both antigens, 51% only ESAT-6 and 10% only CFP-10, whereas 56% of responsive cases recognized both antigens, 30% only ESAT-6 and 13% only CFP-10. Accordingly, CFP-10 response rates were higher for TB cases (odds ratio 2.409, P<0.001). Low purified protein derivative response rates indicated that responses to CFP-10 only were non-specific in contacts. Agreement between peptides in separate versus combined pools was good (kappa=0.758, r=0.840). Therefore a combined ESAT-6/CFP-10 peptide pool provided maximum sensitivity and efficiency, but CFP-10 was mainly required to detect active disease.
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Antígenos Bacterianos/análisis , Proteínas Bacterianas/análisis , Ensayo de Inmunoadsorción Enzimática/métodos , Mycobacterium tuberculosis/inmunología , Tuberculosis Pulmonar/diagnóstico , Adolescente , Adulto , Niño , Femenino , Gambia , Humanos , Masculino , Sensibilidad y Especificidad , Prueba de Tuberculina , Tuberculosis Pulmonar/transmisiónRESUMEN
Contact investigation is a key component of tuberculosis (TB) control in developed, but not developing, countries. We aimed to measure the prevalence of TB among household contacts of sputum-smear-positive TB cases in The Gambia and to assess the sensitivity of an enzyme-linked immunospot (ELISPOT) assay in this regard. Household contacts of adult smear-positive TB patients were assessed by questionnaire, purified protein derivative (PPD) skin test, ELISPOT assay, physical examination, chest X-ray and sputum/gastric aspirate. Thirty-three TB cases were identified from 2174 of 2381 contacts of 317 adult smear-positive pulmonary TB patients, giving a prevalence of 1518/100000. The cases identified tended to have milder disease than those passively detected. The sensitivity of ESAT-6/CFP-10 ELISPOT test as a screening test for TB disease was estimated as 71%. Fifty-six per cent of contacts with a PPD skin test result >or=10mm induration had detectable responses to ESAT-6/CFP-10 by ELISPOT; 11% with a negative PPD skin test (<10mm) had a positive ESAT-6/CFP-10 response. Active screening for TB among contacts of TB patients may have a role in TB control in The Gambia. These individuals are a high-risk group, and the disease identified is less advanced than that found through passive case detection. An ELISPOT assay was relatively insensitive as a screening test for TB.
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Trazado de Contacto/métodos , Tuberculosis Pulmonar/epidemiología , Adolescente , Adulto , Anciano , Niño , Preescolar , Ensayo de Inmunoadsorción Enzimática/métodos , Ensayo de Inmunoadsorción Enzimática/normas , Composición Familiar , Femenino , Gambia/epidemiología , Humanos , Lactante , Masculino , Tamizaje Masivo/métodos , Persona de Mediana Edad , Prevalencia , Sensibilidad y Especificidad , Pruebas Cutáneas/métodos , Esputo/microbiología , Prueba de Tuberculina , Tuberculosis Pulmonar/diagnósticoRESUMEN
BACKGROUND: Repeat tuberculin skin tests may be false positive due to boosting of waned immunity to past mycobacterial exposure. We evaluated whether an ELISPOT test could identify tuberculosis (TB) contacts with boosting of immunity to non-tuberculous mycobacterial exposure. METHODOLOGY/PRINCIPAL FINDINGS: We conducted tuberculin and ELISPOT tests in 1665 TB contacts: 799 were tuberculin test negative and were offered a repeat test after three months. Those with tuberculin test conversion had an ELISPOT, chest X-ray and sputum analysis if appropriate. We compared converters with non-converters, assessed the probability of each of four combinations of ELISPOT results over the two time points and estimated boosting with adjustment for ELISPOT sensitivity and specificity. 704 (72%) contacts had a repeat tuberculin test; 176 (25%) had test conversion, which increased with exposure to a case (p = 0.002), increasing age (p = 0.0006) and BCG scar (p = 0.06). 114 tuberculin test converters had ELISPOT results: 16(14%) were recruitment positive/follow-up positive, 9 (8%) positive/negative, 34 (30%) negative/positive, and 55 (48%) were negative/negative. There was a significant non-linear effect of age for ELISPOT results in skin test converters (p = 0.038). Estimates of boosting ranged from 32%-41% of skin test converters with increasing age. Three converters were diagnosed with TB, two had ELISPOT results: both were positive, including one at recruitment. CONCLUSIONS/SIGNIFICANCE: We estimate that approximately one third of tuberculin skin test conversion in Gambian TB case contacts is due to boosting of immunity to non-tuberculous mycobacterial exposure. Further longitudinal studies are required to confirm whether ELISPOT can reliably identify case contacts with tuberculin test conversion that would benefit most from prophylactic treatment.
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Ensayo de Inmunoadsorción Enzimática/métodos , Reacciones Falso Positivas , Prueba de Tuberculina , Tuberculosis/diagnóstico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Vacuna BCG/inmunología , Niño , Preescolar , Etnicidad , Femenino , Gambia , Humanos , Lactante , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/inmunología , Sensibilidad y Especificidad , Esputo/microbiología , Tuberculosis/microbiología , Tuberculosis/prevención & control , Adulto JovenRESUMEN
BACKGROUND: Options for intervention against Mycobacterium tuberculosis infection are limited by the diagnostic tools available. The Purified Protein Derivative (PPD) skin test is thought to be non-specific, especially in tropical settings. We compared the PPD skin test with an ELISPOT test in The Gambia. METHODOLOGY/PRINCIPAL FINDINGS: Household contacts over six months of age of sputum smear positive TB cases and community controls were recruited. They underwent a PPD skin test and an ELISPOT test for the T cell response to PPD and ESAT-6/CFP10 antigens. Responsiveness to M. tuberculosis exposure was analysed according to sleeping proximity to an index case using logistic regression. 615 household contacts and 105 community controls were recruited. All three tests assessed increased significantly in positivity with increasing M. tuberculosis exposure, the PPD skin test most dramatically (OR 15.7; 95% CI 6.6-35.3). While the PPD skin test positivity continued to trend downwards in the community with increasing distance from a known case (61.9% to 14.3%), the PPD and ESAT-6/CFP-10 ELISPOT positivity did not. The PPD skin test was more in agreement with ESAT-6/CFP-10 ELISPOT (75%, p = 0.01) than the PPD ELISPOT (53%, p<0.0001). With increasing M. tuberculosis exposure, the proportion of ESAT-6/CFP-10 positive contacts who were PPD skin test positive increased (p<0.0001), and the proportion of ESAT-6/CFP-10 negative contacts that were PPD skin test negative decreased (p<0.0001); the converse did not occur. CONCLUSIONS/SIGNIFICANCE: The PPD skin test has surprisingly high specificity for M. tuberculosis infection from recent exposure in The Gambia. In this setting, anti-tuberculous prophylaxis in PPD skin test positive individuals should be revisited.
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Trazado de Contacto/métodos , Prueba de Tuberculina/estadística & datos numéricos , Tuberculosis Pulmonar/diagnóstico , Adolescente , Adulto , Anciano , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Estudios de Casos y Controles , Niño , Preescolar , Trazado de Contacto/estadística & datos numéricos , Ensayo de Inmunoadsorción Enzimática/métodos , Ensayo de Inmunoadsorción Enzimática/estadística & datos numéricos , Femenino , Gambia/epidemiología , Vivienda , Humanos , Lactante , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Linfocitos T/inmunología , Tuberculosis Pulmonar/epidemiología , Tuberculosis Pulmonar/prevención & control , Tuberculosis Pulmonar/transmisiónRESUMEN
The sst1 locus has been identified in a mouse model to control resistance and susceptibility of Mycobacterium tuberculosis infection. Subsequent studies have now identified Ipr1 (intracellular pathogen resistance 1) to be the gene responsible. Ipr1 is encoded within the sst1 locus and is expressed in the tuberculosis lung lesions and macrophages of sst1-resistant, but not sst1-susceptible mice. We have therefore examined the closest human homologue of Ipr1, SP110, for its ability to control susceptibility to M. tuberculosis infection in humans. In a study of families from The Gambia we have identified three polymorphisms that are associated with disease. On examination of additional families from Guinea-Bissau and the Republic of Guinea, two of these associations were independently replicated. These variants are in strong linkage disequilibrium with each other and lie within a 31-kb block of low haplotypic diversity, suggesting that a polymorphism within this region has a role in genetic susceptibility to tuberculosis in humans.
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Predisposición Genética a la Enfermedad/genética , Variación Genética/genética , Mycobacterium tuberculosis/fisiología , Proteínas Nucleares/genética , Tuberculosis/genética , África/epidemiología , Transmisión de Enfermedad Infecciosa , Haplotipos , Humanos , Antígenos de Histocompatibilidad Menor , Tuberculosis/epidemiología , Tuberculosis/microbiología , Tuberculosis/patologíaRESUMEN
RATIONALE: Interferon-gamma (IFN-gamma) is of central interest in the study of tuberculosis. A number of single-gene mutations have been identified in the IFN-gamma signaling pathway that predispose to severe mycobacterial disease, but the relevance of polymorphism within these genes to the common phenotype of tuberculosis remains unclear. METHODS: A total of 1,301 individuals were included in a large, detailed study of West African populations with pulmonary tuberculosis. We investigated disease association with the genes encoding IFN-gamma and its receptor subunits (IFNG, IFNGR1, and IFNGR2). RESULTS: Within the IFNG gene, two promoter variants showed evidence of novel disease association: -1616GG (odds ratio [OR], 1.49; 95% confidence interval [CI], 1.11-2.00; p = 0.008) and +3234TT (OR, 1.40; 95% CI, 1.09-1.80; p = 0.009). The +874AA genotype was not significantly more frequent among cases over control subjects (OR, 1.16; 95%CI, 0.89-1.51; p = 0.25). In addition, novel disease association was also found with the -56CC genotype of the IFNGR1 promoter (OR, 0.75; 95% CI, 0.57-0.99; p = 0.041). No disease association was seen with the IFNGR2 locus. CONCLUSIONS: These results provide evidence of a significant role for genetic variation at the IFNG locus and provide detailed understanding of the genetic mechanisms underlying this association. The disease association with IFNGR1 is novel, and together these findings support the hypothesis that genetically determined variation in both IFN-gamma production and responsiveness influences the risk of developing tuberculosis.
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Polimorfismo de Nucleótido Simple , Receptores de Interferón/genética , Tuberculosis Pulmonar/genética , Adulto , África Occidental , Alelos , Variación Genética , Genotipo , Humanos , Modelos Logísticos , Regiones Promotoras Genéticas , Receptor de Interferón gammaRESUMEN
OBJECTIVE: To compare the enzyme-linked immunospot (ELISPOT) assay with the tuberculin skin test (TST) in children for the diagnosis of Mycobacterium tuberculosis infection in the Gambia. METHODS: We divided child contacts of sputum smear-positive tuberculosis cases into 3 age categories (<5, 5-9, and 10-14 years) and assessed agreement between the 2 tests plus their relationship to prior Bacille Calmette-Guerin (BCG) vaccination. We categorized a child's level of M tuberculosis exposure according to where he/she slept relative to a case: the same room, same house, or a different house. The relationship between exposure and test result was assessed by multiple logistic regression. RESULTS: In child contacts of 287 cases, 225 (32.5%) of 693 were positive by TST and 232 (32.3%) of 718 by ELISPOT. The overall agreement between tests was 83% and the discordance was not significant. Both tests responded to the M tuberculosis exposure gradient in each age category. The percentage of those who were TST positive/ELISPOT negative increased with increasing exposure. At the lowest exposure level, the percentage of ELISPOT-positive children who were TST negative was increased compared with the highest exposure level. Neither test had evidence of false positive results because of BCG. CONCLUSIONS: In Gambian children, the ELISPOT is slightly less sensitive than the TST in the diagnosis of M tuberculosis infection from recent exposure, and neither test is confounded by prior BCG vaccination. Evidence of reduced TST sensitivity in subjects with the lowest known recent M tuberculosis exposure suggests that, when maximal sensitivity is important, the 2 tests may be best used together.
Asunto(s)
Ensayo de Inmunoadsorción Enzimática , Prueba de Tuberculina , Tuberculosis Pulmonar/diagnóstico , Adolescente , Antígenos Bacterianos/inmunología , Vacuna BCG , Niño , Preescolar , Salud de la Familia , Gambia , Humanos , Mycobacterium tuberculosis/inmunología , Tuberculosis Pulmonar/transmisiónRESUMEN
BACKGROUND: New tools are required to improve tuberculosis (TB) diagnosis and treatment, including enhanced ability to compare new treatment strategies. The ELISPOT assay uses Mycobacterium tuberculosis-specific antigens to produce a precise quantitative readout of the immune response to pathogen. We hypothesized that TB patients in The Gambia would have reduced ELISPOT counts after successful treatment. METHODS: We recruited Gambian adults with sputum smear and culture positive tuberculosis for ELISPOT assay and HIV test, and followed them up one year later to repeat testing and document treatment outcome. We used ESAT-6, CFP-10 and Purified Protein Derivative (PPD) as stimulatory antigens. We confirmed the reliability of our assay in 23 volunteers through 2 tests one week apart, comparing within and between subject variation. RESULTS: We performed an ELISPOT test at diagnosis and 12 months later in 89 patients. At recruitment, 70/85 HIV-negative patients (82%) were ESAT-6 or CFP-10 (EC) ELISPOT positive, 77 (90%) were PPD ELISPOT positive. Eighty-two cases (96%) successfully completed treatment: 44 (55%; p < 0.001) were EC ELISPOT negative at 12 months, 17 (21%; p = 0.051) were PPD ELISPOT negative. Sixty (73%) cured cases had a CFP-10 ELISPOT count decrease, 64 (78%) had an ESAT-6 ELISPOT count decrease, 58 (70%) had a PPD ELISPOT count decrease. There was a mean decline of 25, 44 and 47 SFU/2 x 105 cells for CFP-10, ESAT-6 and PPD respectively (p < 0.001 for all). Three of 4 HIV positive patients were cured, all 3 underwent ELISPOT reversion; all 4 not cured subjects (3 HIV-negative, 1 HIV positive) were ESAT-6, CFP-10 and PPD ELISPOT positive at 12 months. CONCLUSION: Successful tuberculosis treatment is accompanied by a significant reduction in the M. tuberculosis-specific antigen ELISPOT count. The ELISPOT has potential as a proxy measure of TB treatment outcome. Further investigation into the decay kinetics of T-cells with treatment is warranted.