Thesis (PhD) -- Stellenbosch University, 2002. / ENGLISH ABSTRACT: Children and adults may differ in their immune function. An adequate function of the individual's immune system is crucial to the risk for development of tuberculosis (TB) after infection with Mycobacterium tuberculosis (Mtb). Epidemiological evidence suggests an age-related incidence of TB. Furthermore, the prevailing clinical expression t ' of TB varies between age groups. -The aims of this study were to characterise the cellular immune response at different ages in TB patients and healthy individuals living in a region highly endemic for TB and to relate the findings to the clinical expression of TB in different age groups. A total of 150 persons of different ages were included in this study: 50 TB patients, (identified on the basis of clinical, radiological and microbiological characteristics), 49 healthy Mantoux positive (~15mm) and 51 healthy Mantoux negative (<15mm) subjects. All patients <12yrs were identified as having primary TB and postprimary TB was only diagnosed in patients ~12yrs. Haematologic indices were obtained from all the included subjects and found to be agerelated. With the exception of the absolute lymphocyte counts, all indices were significantly different in TB patients when compared to healthy controls. Whole blood was cultured and stimulated with PHA, PPD and ESAT -6 to measure lymphocyte proliferation and IFN-y, TNF-a, IL-2 and IL-10 production in the supernatants of the cultures. After stimulation with PHA, the production of IFN-y, TNF-a and IL-10 as well as lymphocyte proliferation were all age-related. After stimulation with PPD, age correlated positively with IFN-y production in healthy Mantoux positive subjects< 12yrs. In the age groups <20 yrs, patients produced similar amounts of IFN-y when compared to healthy age-related Mantoux positive controls. TNF-a and IL-2 production were not different between patients and controls. In this whole blood system, measuring any of these cytokines on their own did not differentiate patients from controls at all ages. The ratio of PPD stimulated IFN-y to TNF-a production was significantly less in patients with primary TB and postprimary TB when compared to Mantoux positive controls, irrespective of age. These findings indicate that calculated ratios between several cytokines may be useful markers of disease at all ages. ESA T -6 stimulated IFN -y production did not result in any significant correlation with age, but was significantly less in healthy Mantoux positive subjects ~12 yrs when compared to healthy Mantoux positive subjects <12 yrs and TB patients of all ages. This finding suggests that a positive immune response to ESAT -6 is indicative of recent immunological contact with Mtb. Total IgE was measured in serum. In children <12 yrs these values correlated with age and were highest in healthy Mantoux positive controls, thereby not confirming any inverse correlation between IgE and TB. Age should be recognised as a significant variable in quantitative measurements of cellular immune responses. / AFRIKAANSE OPSOMMING: Die immuunsisteem van kinders en volwassenes kan verskillend wees. Die mate van immuniteit van 'n individu is deurslaggewend vir die risiko om tuberkulose (TB) na infeksie met die Mycobacterium tuberculosis (M tb) te ontwikkel. Epidemiologiese bevindings suggereer dat die insidensie van TB ouderdomgebonde mag wees. V erder verskil die voorkomende kliniese beeld van TB ook tussen ouderdomsgroepe. Die doelstellings van hierdie studie was om die sellulere immuunrespons op verskillende ouderdomme by TB-pasiente en gesonde individue wat in 'n streek met hoogs endemiese TB-insidensie woon te vergelyk. Die doel was ook om vas te stel hoe hierdie bevindings by die kliniese beeld van TB by verskillende ouderdomsgroepe inpas. Daar is l50 persone van verskillende ouderdomme in hierdie studie ingesluit: 50 TBpasiente (geidentifiseer op grond van kliniese, radiologiese en mikrobiologiese karakteristieke), 49 gesonde Mantoux -positiewe (:2':l5mm) en 5l gesonde Mantouxnegatiewe (<l5mm) persone. Alle pasiente <l2 jaar is gediagnoseer met primere TB. Postprimere TB is alleenlik gediagnoseer in pasiente :2':l2 jaar. Daar is aangetoon dat. hematologiese indekse van al die persone in hierdie studie ouderdomsverwant was. Daar was n beduidende verskil in alle indekse van TB-pasiente in vergelyking met die gesonde kontroles met die uitsondering van die absolute limfosiettellings. Kulture van volbloed is gedoen en gestimuleer met behulp van PHA, PPD en ESAT -6 om limfosiet-proliferasie, IFN-y-, TNF-a-, IL-2- en IL-l0-produksie in die supematante van die kulture te meet. Na stimulasie met PHA was die produksie van IFN-y, TNF-a en IL-l0, asook die limfosiet-proliferasie ouderdomsverwant Na stimulasie met PPD het ouderdom positief gekorreleer met IFN-y produksie in gesonde Mantoux-positiewe persone <l2 jaar. In die ouderdomsgroep <20 jaar het pasiente dieselfde hoeveelhede IFN-y geproduseer as gesonde, ouderdomsverwante Mantoux-positiewe kontroles. Daar was geen verskil tussen die produksie van TNF -a. en IL-2 tussen pasiente en kontroles nie. In hierdie volbloed-sisteem het die meet van nie een van hierdie sitokiene op sigself 'n verskil getoon tussen pasiente en kontroles van aile ouderdomme nie. Die verhouding van PPD-gestimuleerde IFN-y- tot TNF-a.-produksie was betekenisvol minder in pasiente met primere TB en postprimere TB in vergelyking met Mantouxpositiewe kontroles, ongeag ouderdom. Hierdie bevindings toon dat berekende verhoudings tussen verskillende sitokiene waardevoile merkers van 'n siektetoestand {TB) by aile ouderdomme kan wees. ESAT-6 gestimuleerde IFN-y-produksie het geen betekenisvoile korrelasie met ouderdom getoon nie. Daar was egter betekenisvol minder produksie in gesonde Mantoux-positiewe persone ~l2 jaar as in gesonde Mantoux-positiewe persone <l2 jaar, asook in vergelyking met TB-pasiente van aile ouderdomme. Hierdie bevinding kan daarop dui dat 'n positiewe immuun respons op ESAT -6 'n aanduiding van onlangse immunologiese kontak met M tb is. Totale IgE was in serum bepaal. In kinders <l2 jaar het hierdie waardes gekorreleer met ouderdomme en die waardes was die hoogste in gesonde Mantoux-positiewe kontroles. Hierdeur is daar nie bevestig dat daar 'n omgekeerde korrelasie tussen IgE en TB is nie. Ouderdom behoort dus as 'n belangrike veranderlike gesien te word in die kwantitatiewe meting van die sellulere immuunrespons.

Background: In 2015, Swaziland had a tuberculosis (TB) prevalence of 733 per 100 000 population and HIV prevalence of 27.5%. Baylor College of Medicine Children’s Foundation Swaziland (BCMCFSD) reported 83% prevalence of malnutrition amongst children in 2014. No study has described the association between malnutrition and childhood TB in Swaziland. Purpose: To examine the association between malnutrition and diagnosed drug susceptible tuberculosis (TB) amongst children aged zero to fifteen years old in Swaziland. Method: The Mixed Method approach was used to conduct the study. A total of 306 children’s electronic records were extracted, then 12 children’s caregivers interviewed. Extracted data were cleaned and exported to an excel database, then analysed using STATA version 14 by a statistician. Qualitative data were analysed using NVIVO version 11 post the analysis of the quantitative data. Triangulation of quantitative and qualitative results was conducted to obtain a comprehensive picture of the study. Validity, reliability, trustworthiness and adherence to ethical considerations were maintained. Results: History of previous TB treatment, HIV status and age were strongly associated with poor TB outcome (<0.001) and severe malnutrition (<0.002). Sex, regions and TB type were statistically insignificant. Nutritional situation at home and nutritional support from the health care facility, emerged as themes. Conclusion: TB and Malnutrition are significant predictors of children mortality, thus the children caregivers need consistent health education and support. / Health Studies / M. P. H

Tuberculosis (TB) has re-emerged as a major worldwide public health challenge in the last decade with an increasing incidence amongst children. The diagnosis of TB in children is difficult as the presentation is not always classical and available diagnostic modalities are imperfect. Diagnosis is, especially complex in developing countries where resources and access to sophisticated diagnostic facilities are limited. Thus practical score charts combining a number of complementary clinical characteristics with affordable special investigations have been developed to aid diagnosis. The new South African primary health care (PHC) nurse-driven system demands that first line nurses be equipped to suspect, diagnose, confirm the diagnosis and treat children with TB. Very little is known about the ability of PHC nurses to diagnose TB in children. In Mpumalanga province relatively low rates of notified paediatric TB prompted an investigation to determine the ability of local PHC nurses to diagnose TB in children and explore whether the PHC setting allowed this. Within method triangulation was used in this quantitative descriptive study by combining a self-completed knowledge survey with clinic visits to audit records and assess access to diagnostic aids and tests. Important deficiencies in knowledge and limited access to certain diagnostic modalities found in this study must be addressed if appropriate management of TB in children is to be assured. / Health Studies / M. A. (Public Health)

Thesis (MScMedSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Important steps towards the global control of Tuberculosis include the improvement of diagnosis, the development of effective vaccines and the identification of correlates of protection/protective immunity to Mycobacterium tuberculosis. This study has of three objectives: 1. To validate the findings of a previous study that showed increased levels of IL-1β and decreased levels of IL-17 in children who are exposed to tuberculosis but remain uninfected compared to those who are exposed/infected and unexposed/uninfected. 2. To define the protective immunological phenotype in children with negative IGRA’s and TST following exposure to Mycobacterium tuberculosis. 3. To evaluate a number of cytokines in both serum and saliva samples of identified tuberculosis cases and controls for their diagnostic potential and to evaluate saliva as a possible new diagnostic sample type. The study designs were as follows: Objectives1, and 2: Children with documented tuberculosis exposure and with Mycobacterium tuberculosis infection as assessed through interferon gamma release assays, children with exposure but no infection and a control group with no exposure nor infection were investigated. These participants were selected according to their exposure and infection phenotypes from a larger TB household contact study that was conducted in communities in Cape Town. Whole blood was stimulated in QuantiFeron tubes overnight and ten cytokines were measured in antigen stimulated and unstimulated supernatants by Luminex multiplex Immunoassay. Differential production of cytokines in the three groups was evaluated. Objective 3. Saliva and serum samples were collected from thirty eight adults with suspected tuberculosis who were recruited from a community health centre in Cape Town, after which the levels of thirty three host markers were evaluated in the samples using the Luminex platform. The main findings of the studies included: 1. Increased levels of IL-1β and decreased levels of IL-17 in children who are tuberculosis exposed but remain uninfected compared to those who are exposed/infected and unexposed/uninfected could not be confirmed. 2. Immune responses other than IFN-γ are different in children with different exposure and infection phenotypes. Higher IL-23 and IL-33 levels in children with tuberculosis exposure without subsequent Mycobacterium tuberculosis infection compared to children with no exposure were shown. 3. In both the tuberculosis cases and controls, the levels of most markers were above the minimum detectable limit in both serum and saliva, but marker levels were not consistently higher in one sample type. The levels of fractalkine , IL-17, IL-6, IL-9, MIP-1β, CRP, VEGF and IL-5 in saliva, and those of IL-6, IL-2, SAP and SAA in serum, were significantly higher in tuberculosis patients, in comparison to the levels obtained in those without active tuberculosis (p<0.05). The area under the ROC curve was ≥ 0.70 for most of these markers, thereby confirming their diagnostic potential for TB disease. The work presented in this thesis has identified markers that may grant an improved understanding on the mechanisms that are associated with protection against Mycobacterium tuberculosis in children. The preliminary results presented show that the identification of host markers in saliva is possible and the utility of saliva for the development of rapid immune-based tests for active tuberculosis is promising. / AFRIKAANSE OPSOMMING: Noemenswaardige vooruitgang in die globale beheer van Tuberkulose is onderworpe aan verbeterde diagnose, die ontwikkeling van doeltreffende vaksienes en die identifikasie van aanwysers van immuniteit teen Mycobacterium tuberculosis. Die doel van hierdie studie is: 1. Om die bevindinge van ‘n vorige studie te bevestig, waar verhoogde vlakke van IL-1β en verlaagde vlakke van IL-17 waargeneem is in kinders wat aan tuberkulose blootgestel is, maar nie geïnfekteer is nie. Hierdie bevindinge was in vergelyking met geïnfekteerde en nie-blootgestelde kinders. 2. Om ‘n beskermende immunologiese fenotipe te definieer in kinders met negatiewe IGRA’s en TST, na blootstelling aan Mycobacterium tuberculosis. 3. Om sekere sitokines, in beide serum en speeksel monsters van tuberkulose gevalle en kontroles, te evalueer as potensiële diagnosemiddels, asook die moontlikheid dat speeksel kan dien as ‘n nuwe diagnostiese monstertipe. Die studieraamwerk was as volg: Doel 1 &2:Die volgende groepe was onder meer ondersoek – Kinders blootgestel aan tuberkulose en wat gevolglik geïnfekteer is, soos vasgestel deur interferon gamma vrystellingstoetse; kinders wat wel blootgestel is maar nie geïnfekteer is nie en ‘n kontrolegroep wat geen blootstelling aan Mycobacterium tuberculosis gehad het nie. Hierdie individue is geselekteer volgens hul blootstellingsprofiel en infeksiefenotipes, uit ‘n groter blootstellingstudie op Kaapse huishoudings. Heelbloed is oornag gestimuleer en tien sitokiene is gemeet in antigeen-gestimuleerde en ongestimuleerde supernatante, deur middel van Luminex multipleks Immunotoetse. Differensiële produksie van sitokienes in hierdie groepe is gevolglik geëvalueer Doel 3: Speeksel en serummonsters van 38 volwassenes met vermeende tuberkulose, is versamel en die vlakke van drie en dertig gasheermerkers is gemeet deur middel van die Luminex platvorm. Die hoof bevindinge van hierdie studie sluit in: 1.Vehoogde vlakke van IL-1β en verlaagde vlakke van IL-17 kon nie bevestig word in die verskeie kindergroepe (Sien doel 1) nie. 2. Die immuunrespons, uitsluitend die IFN- γ respons, is veskillend in kinders met uiteenlopende blootstelling en infeksiefenotipes. Hoër vlakke van IL-23 en IL-33 is gevind in kinders wat blootgestel is aan tuberkulose, maar nie geïnfekteer is nie, in teenstelling met nie-blootgestelde kinders.. 3. In beide die pasiënte en kontroles was die meeste sitokienvlakke hoër as die minimum meetbare limiet in beide speeksel en serummonsters, hoewel merkervlakke nie konstant hoër was in enige van die twee monstertipes nie. Die vlakke van fractalkine, IL-17, IL-6, IL-9, MIP-1β, CRP, VEGF en IL-5 in speeksel en IL-6, IL-2, SAP en SAA in serum, was merkbaar hoër in tuberkulosepasiënte, in vergelyking met vasgestelde vlakke in individue sonder aktiewe tuberkulose. (p<0.05). Die oppervlak onder die ROC kurwe was ≥ 0.70 vir die meerderheid van die merkers. Dit is ‘n sterk aanduiding dat hierdie merkers potensiaal het as diagnostiese merkers vir tuberkulose. Hierdie navorsing het merkers geïdentifiseer wat die begrip van die megansime waarmee beskerming teen Mycobacterium tuberculosis gebied word in kinders, verbreed. Hierdie voorlopige resultate dui aan dat die identifikasie van gasheermerkers in speeksel moontlik is en dat speeksel moontlik kan dien as ‘n proefkonyn vir die ontwikkeling van immuungebaseerde sneltoetse vir die diagnose van aktiewe tuberkulose. / The EDCTP through the African European Tuberculosis Consortium (AE-TBC, grant number IP_2009_32040) / Trials of Excellence in Southern Africa (TESA, project code CG_cb_07_41700)

Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Childhood tuberculosis is an infectious disease that can cause serious illness and mortality in especially young children. Following contact with an infectious adult tuberculosis case, the disease is easily preventable through preventive isoniazid treatment, yet very few exposed and at-risk children currently access this healthcare service in most high-burden settings. Previous research pointed out the multifactorial and complex nature of the barriers to accessing preventive care. Specifically, the lack of a formalised recording and reporting tool, such as the universally used tuberculosis treatment registers, possibly contribute to the operational barriers of preventive care delivery to these children. The purpose of this research was to evaluate the cost-effectiveness of an isoniazid preventive treatment register tool used at community level. The study utilised previously reported data from the study population and other high-burden settings to construct a decision analysis model that included varying probabilities of isoniazid preventive treatment across three high risk age groups (<1 year of age, 1 – 2 years of age, 3 – 5 years of age), coupled with disease probabilities and associated treatment costs. The scenarios simulated included 1) the routine isoniazid preventive treatment service (3% started on treatment, 17% identified as eligible); and 2) an isoniazid preventive treatment service supported by a recording register (15% (adherent to six months of treatment) and 38% (started on IPT treatment)). In addition, two hypothetical simulations were included for 76% and 100% isoniazid preventive treatment uptake; these hypothetical simulations required additional community based healthcare worker resources in addition to the register tool. The observations from the literature indicated that more children were identified (24(17%) vs. 54(38%)) and started (4(3%, base case) vs. 54) on isoniazid preventive treatment following the implementation of the register. As expected, the mean number of tuberculosis cases prevented, increased as the proportion of eligible children that received isoniazid preventive treatment, improved; the change in the number of cases prevented per simulation showed incremental improvements which were all significantly better (p<0.01) than the base case.. The incremental cost-effectiveness ratios incurred savings for each of the scenarios simulated since the mean costs for each of the simulations were significantly less (p<0.01) than the costs associated with the base case. The current evidence suggests that the proposed isoniazid preventive treatment register tool is a cost-effective alternative to the current standard of care in place at community level for at-risk children exposed to tuberculosis. It is therefore recommended that the tool be used incrementally on a bigger scale, until such time that sufficient evidence has been generated to support widespread implementation.

Tuberculosis (TB) has re-emerged as a major worldwide public health challenge in the last decade with an increasing incidence amongst children. The diagnosis of TB in children is difficult as the presentation is not always classical and available diagnostic modalities are imperfect. Diagnosis is, especially complex in developing countries where resources and access to sophisticated diagnostic facilities are limited. Thus practical score charts combining a number of complementary clinical characteristics with affordable special investigations have been developed to aid diagnosis. The new South African primary health care (PHC) nurse-driven system demands that first line nurses be equipped to suspect, diagnose, confirm the diagnosis and treat children with TB. Very little is known about the ability of PHC nurses to diagnose TB in children. In Mpumalanga province relatively low rates of notified paediatric TB prompted an investigation to determine the ability of local PHC nurses to diagnose TB in children and explore whether the PHC setting allowed this. Within method triangulation was used in this quantitative descriptive study by combining a self-completed knowledge survey with clinic visits to audit records and assess access to diagnostic aids and tests. Important deficiencies in knowledge and limited access to certain diagnostic modalities found in this study must be addressed if appropriate management of TB in children is to be assured. / Health Studies / M. A. (Public Health)

Depuis peu, un intérêt croissant est manifesté pour l’étude de la tuberculose pédiatrique ;les enfants constituent, en effet, une grande partie du réservoir des futurs cas de tuberculose active (TBA) maladie. Selon les estimations de l’Organisation Mondiale de la Santé (OMS), ce réservoir est constitué par 2 milliards de personnes porteuses d’une forme latente de tuberculose (LTBI). La LTBI est définie par l’existence d’une réponse immunitaire adaptative aux antigènes de Mycobacterium tuberculosis (M.tuberculosis) en l’absence de signes cliniques de maladie. A partir de ce réservoir, 8,7 millions de nouveaux cas de TBA et 1,4 millions de décès liés à ces TBA ont été déclarés par l’OMS en 2011. On estime que la TBA pédiatrique, dont l’ampleur réelle est probablement sous-estimée, représente 9 à 12 % de tous les cas incidents. <p>Une meilleure coordination des efforts et leur augmentation à l’échelle mondiale, au cours de ces dernières années, a permis de réduire l’incidence de la TB en diagnostiquant, traitant rapidement et plus efficacement les TBA. Cette stratégie est insuffisante si l’objectif, comme défini par l’OMS à l’horizon de 2050, est d’éradiquer la TB. Il faudrait, pour cela, développer de nouvelles stratégies vaccinales pour améliorer l’efficacité du bacille Calmette et Guérin (BCG), mais également s’attaquer au réservoir de M. tuberculosis. <p>Le seul vaccin disponible, le BCG, confère une protection variable et souvent faible contre la TB pulmonaire. La stratégie, dans le développement de vaccins contre la tuberculose, est de mimer les réponses immunitaires naturelles développées par les sujets avec une LTBI puisque 90% d’entre eux sont définitivement protégés contre la maladie. Il apparaît donc important de caractériser ces réponses de l’immunité adaptative qui apparaissent lors d’une primo-infection par M. tuberculosis (avant l’état de latence) chez l’homme. L’étude de ces réponses immunitaires primaires est difficilement réalisable chez les adultes car, chez la majorité d’entre eux, les cas de TBA résultent soit d’une réactivation, soit d’une réinfection. Dans un pays à faible prévalence comme la Belgique où, par ailleurs, la vaccination par le BCG n’est pas administrée en routine, l’étude d’un « groupe modèle » constitué d’enfants exposés à M. tuberculosis est une opportunité inespérée pour caractériser la réponse immunitaire primaire spécifique. La comparaison des réponses immunitaires de primo-infection aux réponses immunitaires secondaires (enfants exposés à M. tuberculosis et précédemment vaccinés par le BCG) présente également un intérêt pour l’établissement de nouvelles stratégies vaccinales telles que le « prime-boost ». De plus, les approches vaccinales actuelles incluent préférentiellement les antigènes de la phase réplicative alors que l’ajout d’un antigène de latence pourrait induire une réponse immunitaire plus protectrice et plus complète.<p>Les réponses de l’immunité adaptative primaires ou secondaires des jeunes enfants dirigées contre les antigènes de M. tuberculosis sont relativement peu caractérisées si bien que les facteurs responsables de la grande susceptibilité des enfants à développer une infection sévère sont loin d’être complétement identifiés. Par ailleurs, au vu des difficultés diagnostiques de l’infection par M. tuberculosis chez l’enfant et, en particulier, de différentier les TBA des formes latentes, de nombreuses recherches sont menées pour tenter d’identifier des biomarqueurs qui pourraient aider à séparer ces deux phénotypes. En effet, la TBA pédiatrique est pauci-bacillaire, ce qui rend les moyens diagnostiques classiques comme la microbiologie et/ou la biologie moléculaire, tous deux dépendant de la charge mycobactérienne, peu sensibles. De plus, le diagnostic de la LTBI par le test cutané à la tuberculine (TCT)et les tests in vitro aujourd’hui commercialisés mesurant les sécrétions d’interféron-gamma (IFN-γ), les IGRA, ne sont pas suffisamment sensibles et spécifiques, surtout chez les enfants de moins de 5 ans.<p>L’étude des réponses immunitaires induites par la « Heparin-Binding Haemagglutinin » (HBHA) a été menée dans l’objectif d’améliorer la performance des techniques de laboratoire. La HBHA est une adhésine exprimée par le complexe M. tuberculosis. Elle est impliquée dans la dissémination extrapulmonaire du bacille et constitue donc un facteur de virulence. Par ailleurs, dans un modèle murin, le caractère protecteur d’une vaccination avec la HBHA contre l’infection par M. tuberculosis a également pu être démontré ;l’efficacité était comparable à celle du vaccin BCG. Si l’effet d’une telle vaccination n’a pas encore été évalué chez l’homme, l’immunogénicité de cet antigène a, par contre, pu être établie en clinique humaine. En effet, les lymphocytes circulants, isolés chez des adultes infectés par M. tuberculosis de façon latente, sécrètent plus d’IFN-γ en réponse à la HBHA que les lymphocytes des patients présen-tant une TBA non traitée. La HBHA est donc un antigène de latence puisqu’il induit une réponse immunitaire principalement pendant cette phase. De plus, la HBHA est une protéine méthylée et la méthylation s’avère essentielle pour garantir ses propriétés immuno-protectrices. <p>Nos travaux ont été orientés selon deux axes :d’une part, l’analyse des réponses immunitaires primaires et secondaires dirigées contre la HBHA comparées à celles induites par des antigènes spécifiques de M.tuberculosis connus et, d’autre part, l’exploitation de la réponse immunitaire à la HBHA ainsi qu’à d’autres antigènes spécifiques de M. tuberculosis dans le but de définir des biomarqueurs de susceptibilité et proposer de nouveaux moyens immuno-diagnostiques. <p>L’évaluation de la réponse immunitaire primaire, chez les enfants de moins de 5 ans et non vaccinés par le BCG, aux antigènes mycobactériens spécifiques démontre que la réponse IFN-γ primaire induite par la HBHA est peu élevée quantitativement chez les enfants infectés par M. tuberculosis contrairement aux réponses IFN-γ induites par les antigènes de la phase réplicative, l’ESAT-6 et le CFP-10. Cette faiblesse de la réponse immunitaire, de type TH1, vis–à-vis de la HBHA, n’est pas due à une immaturité du système immunitaire des jeunes enfants ni à un shift des réponses vers un profil cytokinique de type TH2. Elle reflète pro-bablement le phénotype clinique de l’infection affiché par ces jeunes enfants récemment infectés par M. tuberculosis qui ne sont pas encore parvenus au stade de latence. Cette faible réponse pourrait, néanmoins, constituer un biomarqueur de susceptibilité accrue à la TB des jeunes enfants. De plus, si la réponse primaire HBHA-spécifique n’est quantitativement pas différente de celle des enfants présentent une TBA ou une LTBI, elle l’est cependant qualitativement si l’on compare ces deux phénotypes cliniques. En effet, seuls les enfants «protégés» (avec une LTBI ou une TBA traitée) présentent des réponses envers des épitopes protecteurs de la forme méthylée de la HBHA. La mise en évidence de réponses contre ces épitopes de la forme méthylée pourrait donc être évaluée en tant que biomarqueur de protection. Parallèlement, l’absence ou la présence d’une telle réponse dirigée contre les épitopes de cette forme méthylée de la HBHA pourrait également permettre de différentier un enfant avec une TBA d’un enfant avec une LTBI. <p>La caractérisation de la réponse immunitaire se-condaire à la HBHA, chez les enfants infectés par M. tuberculosis et préalablement vaccinés par le BCG, a permis de démontrer que cette réponse est quantitativement plus importante si on la compare aux réponses de type primaire. <p>Puisque le caractère protecteur du BCG adminis-tré à la naissance est bien reconnu, il semblerait logique d’utiliser en priorité la HBHA dans une approche vaccinale «prime-boost », c’est-à-dire une amplification par la HBHA d’une immunité «protectrice» déjà acquise lors de l’administration du vaccin BCG dans l’enfance.<p>L’exploitation de l’analyse des réponses immuni-taires induites par les antigènes spécifiques de M. tuberculosis, l’ESAT-6, le CFP-10 et la HBHA, a ensuite permis d’établir que la réponse IFN-γ induite par la HBHA est faible chez l’enfant et non discriminante entre une TBA et une LTBI, ce qui limite l’intérêt diagnostique de la HBHA chez l’enfant contrairement à ce qui a pu être observé chez les adultes. Par contre, les résultats des tests IGRA à longue durée d’incubation utilisant l’ESAT-6 et surtout le CFP-10 comme antigènes, peuvent apporter des arguments en faveur d’une infection par M. tuberculosis chez l’enfant et être ainsi intégrés dans la triade diagnostique utilisée par les pédiatres. En effet, la mise en évidence d’une réponse IFN-γ induite par le CFP-10 très élevée est plus souvent associée à une TBA et, en combinaison avec le TCT ou la PPD-IGRA, elle a permis d’identifier, au sein du groupe d’enfants que nous avons étudié, ceux qui présentaient une TBA. <p>Les tests immuno-diagnostiques in vitro et in vivo manquent de sensibilité pour le diagnostic des TBA extra-pulmonaires. Dans ces cas particuliers, l’analyse de la réponse IFN-γ par les lymphocytes isolés directement au niveau du site d’infection apparait prometteuse chez l’enfant. Parmi les TB extra-pulmonaires, l’adénite tuberculeuse est une présentation fréquente difficile à différentier cliniquement ou radiologiquement d’une lymphadénopathie causée par une autre mycobactérie non tuberculeuse comme M.avium. Souvent, le recours à une technique d’investigation plus invasive (biopsie) est nécessaire. Nous avons développé au sein du laboratoire des tests in vitro comparant la réponse IFN-γ induite par la PPD-tuberculosis et la PPD-avium. Le ratio entre ces deux réponses permet d’orienter le clinicien dans le diagnostic différentiel entre des infections induites par l’une ou l’autre de ces deux mycobactéries et permettra peut-être à l’avenir de ne pas imposer aux patients la pratique de manœuvres chirurgicales.<p><p>En conclusion, ce travail confirme que la suscepti-bilité des jeunes enfants aux formes sévères de tuberculose n’est pas la conséquence d’un « état d’immunodéficience ». Par ailleurs, ils sont ca-pables de développer une réponse immunitaire contre la HBHA, candidat pour le développement d’un nouveau vaccin ou d’une nouvelle stratégie vaccinale contre la tuberculose. Enfin, nous avons identifié de nouveaux biomarqueurs susceptibles d’aider les pédiatres à diagnostiquer et à différencier les différentes formes que peut prendre l’infection tuberculeuse chez leurs jeunes patients. <p> / Doctorat en sciences médicales / info:eu-repo/semantics/nonPublished

Thesis (MScMedSc) -- Stellenbosch University, 1998. / Bibliography / ENGLISH ABSTRACT: There is a progressive maturation of the immune system from infancy to adulthood. The immature immune system in early life is characterised by impaired macrophage function and antigen presentation as well as a higher naIve to memory T cell ratio with subsequent diminished IFN-y production. Children with tuberculosis often present with lymphadenopathy, the complications thereof or with systemic spread of the organisms. Adults generally manifest with pronounced systemic effects (such as weight loss and high fever) and immunopathology (such as cavitation and fibrosis). We hypothesised that the immunopathology in adults may be due to enhanced cytokine production in comparison to children. The first aim of this study was therefore to measure cytokine responses in healthy children and adults. Cytokine responses in patients with tuberculosis will be examined in future studies. Peripheral blood mononuclear cells (PBMC) were isolated from whole blood obtained from 9 healthy children and 9 healthy adults. The cells were cultured in serum-free medium, unstimulated or polyclonally stimulated with Phytohaemagglutinin (PHA). Supernatants were harvested after which IFN-y, IL-2, TNF-a., IL-4 and IL-IO production was determined by means of ELISA analysis. Ri'J"A was ~ubsequently extracted from the cells followed by RT-PCR analysis for the semiquantitative determination of mRNA levels of these cytokines. PBMC isolated from healthy children produced significantly less IFN-y protein than adults. Futhermore, IFN-y production in the adults seemed to be trimodally distributed. No significant differences could be found in the production of IL-2, TNF-a, IL-4 and IL-] O. Although children produced low levels of IFN-y protein, their IFN-y, TNF-a, IL-2, IL-4 and IL-IO mRNA levels were comparable to that of adults. Tuberculosis is a major cause of mortality and morbidity, particularly in the third world. Ravensmead and Uitsig, two adjacent suburbs in the Western Cape, have a tuberculosis incidence of> I 000/100000 population. Also, up to 90 % of the children in the Western Cape have been reported to be infested by intestinal parasites such as Ascaris lumbricoides and Trichurius trichl/ria. Infection with M tuberculosis indut:es a Th 1 Stellenbosch University http://scholar.sun.ac.za iv In:.,c response, while intestinal parasites elicit a Th2 immune response. Th2 dominance induced by intestinal parasite infestations could predispose individuals to an enhanced susceptibility to M. tuberculosis. The second aim of this study was to investigate serum IgE levels, surrogate markers for Th2 activation, in the community. The serum 19B levels were subsequently correlated to the tuberculosis incidence per enumerator sub-district (ESD), crowding, female literacy and socio-economic levels. Similarly, the tuberculosis incidence per ESD was correlated with the above mentioned parameters. A significant positive correlation was found between tuberculosis incidence and the serum 19E levels in the community. However, further studies are needed to determine if intestinal parasites are the main cause of the high 19B levels in the community and to dCh111ine if parasite loads or Th2 dominance are causally linked to the incidence of tuberculosis. Correlation between serum 19E levels and tuberculosis incidence with the other parameters were significant, except in the case of crowding. The third aim of this study was to measure serum IgE and specific 19E levels against Ascaris and common allergens on presentation of tuberculosis and again after completion of successful treatment. Significant declines in serum 19B and Ascaris specific 19B levels were observed after completion of tuberculosis treatment. This down regulation of IgE levels may be due to an up regulation of ThI responses in patients following successful treatment for tuberculosis. / AFRIKAANSE OPSOMMING: Die immuunsisteem matureer toenemend vanaf kinderjare tot en met volwassewording. Die onvolwasse immuunsisteem van jong kinders word gekenmerk deur verswakte makrofaag-funksionering en antigeenpresentering, sowe) as 'n verhoogde naiwe tot geheue T-sel verhouding met gevolglikc verminderde IFN-y produksie. Kinders met tuberkulose presenteer gewoonlik met Iimfadenopatie, komplikasies daarvan of met gedissemineerde siekte. Volwassenes presenteer met sistemiese gevolge (soos gewigsverlies en hoe koors) en immunopatologie (soos kavitasie en fibrose). Ons hipotese is dat die immunopatologie in volwassenes die gevolg is van 'n verhoogde sitokienproduksie in vergelyking met kinders. Die eerste doelwit van die studie was om sitokienproduksie in gesonde kinders en volwassenes te meet. Sitokienproduksie in tuberkulose pasiente sal in 'n opvolgstudie bepaal word. Perifere bloed mononukleere selle was geisoleer vanuit heel bloed verkry vanaf 9 gesonde kinders en 9 gesonde volwassenes. Die selle was gekweek, ongestimuleer of gestimuleer met Phytohaemagglutinien (PHA). Supernatante was geoes vir die bepaling van IFN-y, IL-2, IL-4, IL-I0 en TNF-a. produksie, deur gebruik te maak van ELISA analise. RNA was gevolglik vanaf die selle ge-ekstraheer vir die tru-transkriptase polimeerketting reaksie analise, waartydens sitokien mRNA vlakke op 'n semi-kwantitatiewe wyse bepaal was. Perifere bloed mononukleere selle geisoleer vanaf die kinders het minder IFN-y geproduseer as die van volwassenes. Hierdie verminderde produksie was hoogs betekenisvol. Dit wou voorkom asof die IFN-y produksie deur volwassenes trimodaal versprei was. Geen betekenisvolle verskille tussen kinders en volwassenes kon gevind word in die produksie van IL-2, IL-4, IL-IO en TNF-a nie. Alhoewel kinders minder IFN-y proteien geproduseer het, het hulle IFN-y, IL-2, IL-4, IL-JO en TNF-a mRNA produksie met vlakke van volwassenes ooreengestem. Tuberkulose speel 'n groat rol in morbiditeit en mortaliteit in veral die derde wereld. Ravensmead en Uitsig, twee aangrensende voorstede in die Wes-Kaap, het 'n tuberkulose voorkomssyfer van> 1 000/1 00000 populasie. Verder, is tot 90 % van die kinders in die Stellenbosch University http://scholar.sun.ac.za VI Wes-Kaap gei'nfesteer met intestinale parasiete soos Ascaris Ilimbricoides en Trichllrills trichllria. M. tuberculosis infeksie induseer 'n Thl immuunrespons, terwyl intestinale parasiete 'n Th2 immuunrespons uitlok. 'n Dominante Th2 respons mag moontlik individue predisponeer tot 'n verhoogde vatbaarheid vir M. tuberculosis. Gevolglik was die tweede doelwit van die studie om serum IgE vlakke as surrogaat merkers vir Th2 aktivering in die gemeenskap bestudeer. Die serum IgE vlakke was gevolglik gekorreleer met die tuberkulose voorkoms per opnemerssensusgebied (OSG), saamdringing, vroulike geletterdheid en sosio-ekonomiese vlakke. Die tuberkulose voorkoms per OSG, is op dieselfde wyse gekorreleer met die bogenoemde parameters. 'n Betekenisvolle positiewe korrelasie is gevind tussen tuberkulose voorkoms en serum IgE vlakke in die gemeenskap. Verdere stuciies is egter nodig om te bepaal of intestinale parasiete weI die oorsaak van die hoe IgE vlakke in die gemeenskap is en of parasiet ladings of Th2 dominansie oorsaaklik verbind kan word aan die tuberkulose voorkoms. Die derde doelwit van die studie was om serum 19E en spesifieke IgE vlakke teen Ascaris en algemene allergene te meet met presentering van tuberkulose en weer na voltooing van suksesvolle behandeling. 'n Betekenisvolle afname in serum 19E en Ascaris spesifieke 19E vlakke is waargeneem na vohooing van tuberkulose behandeling. Die afregulering van 19E vlakke kan moontlik toegeskryf word aan die opregulering van Th1 response in pasi"ente na voltooing van suksesvolle behandeling van tuberkulose.

M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / Background: There are critical unmet needs for improved strategies in the detection and diagnosis of M.tuberculosis infection in children, and for prevention of tuberculosis disease in children. Bacillus Calmette-Guérin (BCG) vaccination has limited the utility of tuberculin skin testing (TST) in areas with high vaccine coverage. Objectives: The aim of this study was to estimate the prevalence of M.tuberculosis infection in children with household tuberculosis contacts, using QFT-GIT testing in comparison with TST. Methods: This study was a cross-sectional design to assess the performance of a new T-cell based blood test, namely QuantiFERON-TB Gold In Tube (QFT-GIT), for diagnosis of tuberculosis infection in the children (n=182) of adults (n=124) with pulmonary tuberculosis, additionally to determine the prevalence of M.tuberculosis infection in children with household tuberculosis contacts, using QFT-GIT testing in comparison with TST. The study was carried out at Chris Hani Hospital. For children involved in the study, tuberculosis exposure information was obtained, together with TST, QFT-GIT, and HIV testing. Data obtained from both experiments was statistically analysed using SPSS version 24 to determine whether there was a significant agreement between QFT-GIT and TST on the detection of M.tuberculosis prevalence in children with house hold contacts with confirmed M.tuberculosis infection. Results: This study examined the sensitivity and specificity of the QFT-GIT tests compared with the standard TST for diagnosing latent tuberculosis disease in paediatric contacts. Because of the lack of a latent tuberculosis “gold standard”, the specificity and sensitivity of QFT-GIT was calculated with a two-by-two table method. The specificity of the QFT-GIT was 84% and the sensitivity was 85%. There was a good correlation between QFT-GIT and TST (Cohen’s kappa of 0.705). Seventeen percent (17%) of the 182 children tested by QFT-GIT yielded indeterminate results. Age was associated with indeterminate QFT-GIT results in paediatric tuberculosis contacts. Point prevalence for QFT-GIT was recorded as 31% at baseline and 39.5% after six months indicating variability between QFT-GIT results at baseline and after six months. Conclusion: It was concluded that the prevalence of tuberculosis infection was common among South African children who live with an adult with active tuberculosis. The agreement between QFT-GIT assay and TST for the diagnosis of latent tuberculosis in children was high. Although TST and QFT-GIT assays appeared comparable, QFT-GIT showed higher positivity rate amongst those contacts with reported household tuberculosis exposure compared to TST. The QFTGIT assay was a better indicator of the risk of M.tuberculosis infection than TST in a BCG-vaccinated population.

Thesis (Mnutr)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Problem Definition: In the context of HIV/AIDS malnutrition is almost universal among children, and of the adverse effects of Protein Energy Malnutrition, the most frequent seems to be the occurrence of opportunistic infections with micro-organisms such as oral Candida. Objective: The aim of this study was to determine the nutritional status of children with oral complications in relation to HIV/AIDS as well as the effects of the oral lesions on nutritional status. Subjects/setting: The subjects of study were 24 children co-infected with TB and HIV who were admitted consecutively to the paediatric ward of Brooklyn Chest Hospital in Cape Town, South Africa. The nutritional status of the children was assessed over a maximum period of six months by nutrient intake, anthropometric status, and by biochemical parameters and clinical and oral examination on admission and at discharge from hospital. Results: Children with HIVand TB infection presenting with or without oral lesions were similarly malnourished throughout the period of hospitalization. There was no improvement in the nutritional status as indicated by height and weight measurements. Throughout the time of hospitalization, 7% of the children had a combination of stunting, underweight and wasting. Average nutrient intake was not found to be higher than the Recommended Dietary Allowance (RDA) in any of the children. At the time of admission to hospital and at discharge, carbohydrate intake provided most of the daily energy (36% and 42%, the difference not being statistically significant). There was a significant increase in the intake of energy (p=O.04) and a decrease in total fat intake (p=O.03) at discharge. Although not significant, mean protein intake at admission was higher than at time of discharge. Selected sub-optimal biochemical values were prevalent among the children studied, with 45% and 41% showing low serum albumin values «2.9g/dL) at the time of admission and at discharge respectively. Both on admission and at discharge, 38% of the children had Haemoglobin levels below normal values. Serum ferritin levels below normal values were present in almost all the children and the trend was similar for the prevalence of low zinc values. Sub-normal plasma retinol was present in 79% of the children at time of admission, while only 21% had deficient values at time of discharge (p=O.03). On admission, 29% of the children had vitamin evalues below the normal range whereas at time of discharge 17% of the children had values below normal (p=O.04). A total of 29% children presented with oral complications on admission. These included oral herpes, oral thrush, reflux, bleeding gums and stomatitis/angular cheilosis. Two children were asymptomatically colonized with Candida of the oral cavity. Mean total protein intake was higher (p=O.057) among the children who were not diagnosed with oral complications. Conclusions: This study confirmed that malnutrition is not only a common and serious problem associated with HIVand AIDS, but also that nutritional problems cannot be dealt with in isolation where Opportunistic Infections are present. The severity of malnutrition depends on various factors including oral complications. Additionally, appropriate management and treatment of tuberculosis did not appear to affect the nutritional status significantly. Recommendations: On the basis of these findings, and because of the increased risk of growth failure and developmental delays, children should be referred for full nutritional evaluation as soon as possible after diagnosis of HIV -infection. In addition, there is a need for intervention programmes to identify the immediate underlying causes of malnutrition and the ways in which such causes interact, in order to ensure that such interventions increase the resistance of HIV infected infants and children to the disease. / AFRIKAANSE OPSOMMING: Probleemdefiniëring: Binne die konteks van MIVNIGS is wanvoeding bykans universeelonder kinders en van die nadelige effekte van proteïen energie wanvoeding is die voorkoms van opportunistiese infeksies (Ol) met mikro-organismes soos orale candida die algemeenste. Doelwit: Die doel van dié studie was om die voedingstatus van kinders met orale komplikasies in verhouding tot MIVNIGS en die effek van orale letsels op voedingstatus, te bepaal. Proefpersone/omgewing: 'n Groep van 24 kinders, met beide tuberkulose en MIVNIGSinfeksie, wat agtereenvolgend in die kindersaal van Brooklyn Bors-Hospitaal in Kaapstad, Suid- Afrika opgeneem is, is bestudeer. Vir 'n periode van ses maande is die kinders se voedingstatus geassesseer deur middel van voedingstofinname, antropometriese status en biochemiese parameters met opname in en ontslag uit die hospitaal. Kliniese en orale ondersoeke was op elke kind uitgevoer met opname sowel as ontslag. Resultate: Kindres met HIV en tuberkulose, met of sonder orale letsels, het soortgelyke wanvoeding tydens hospitalisering ervaar het. Volgens antropometriese metings was daar geen verbetering in die voedingstatus nie. 'n Kombinasie van belemmerde groei, ondergewig en uittering het in 7% van die kinders tydens hospitalisering voorgekom. Nie een van die gemiddeldes van die voedingstowwe was hoër as die Aanbevole daaglikse toelatings (ADT) in enige van die kinders wat bestudeer is nie. Met opname sowel as ontslag, was koolhidraatinname die grootste energieverskaffer met onderskeidelik 36% en 42% (alhoewel die verskil nie statisties beduidend was nie). Daar was 'n beduidende toename in energie-inname (p=O.04) en 'n afname in totale vetinname (p=O.03) met ontslag. Alhoewel nie beduidend nie, was die gemiddelde proteïeninname hoër met ontslag. Die voorkoms van geselekteerde sub-optimale biochemiese waardes met toelating en ontslag wys dat onderskeidelik 45% en 41% van die kinders lae serum albumienwaardes «2.9g/dL) getoon het. Subnormale plasma retinol het in 79% van die kinders met toelating voorgekom, terwyl slegs 21% gebrekkige waardes (p=O.03) met ontslag getoon het. Tydens opname, sowel as met ontslag, was 38% van die kinders se hemoglobienvlakke laer as die normale. Serum ferritienvlakke was amper by al die kinders laer as die normale vlakke te bespeur, met sinkvlakke wat op soortgelyke lae vlakke voorkom. Met toelating was 29% van die kinders se Vitamien C-waardes laer as normaal en met ontslag was sowat 17% se waardes steeds laer as die normaal (p=O.04). Met toelating het 29% van die kinders orale komplikasies getoon. Ingeslote hierby was orale herpes, orale sproei, refluks, bloeiende tandvleise en stomatis/ angulêre cheilose. Slegs twee kinders was asimptomaties met orale Candida van die mondholte gediagnoseer. Die gemiddelde proteïeninname was hoër (p=O.057) onder die kindres wat nie orale komplikasies getoon het nie. Gevolgtrekking: Hierdie studie bevestig dat wanvoeding me net 'n algemene en ernstige probleem is wat met MIV en VIGS geassosieer word nie, maar ook in die teenwoordigheid van opportunistiese infeksies, die voedingsprobleem nie in isolasie gehanteer kan word nie. Die graad van wanvoeding hang af van ander faktore, insluitende orale komplikasies. Voldoende behandeling van TB het ook nie 'n beduidende effek op voedingstatus gehad nie. Aanbevelings: Op hierdie bevindings gebaseer, en as gevolg van die verhoogde risiko VIr belemmerde groei en vertraagde ontwikkeling wat al die liggaamstelsels van MIV -positiewe kinders affekteer, moet kinders so gou as moontlik nadat die MIV-infeksie gediagnoseer is, vir volle voedingsevaluasies verwys word. Daarmee gepaardgaande is daar 'n behoefte aan programme wat die onmiddellike onderliggende oorsake van wanvoeding identifiseer, asook om interaksie van hierdie oorsake met HIV vas te stel, ten einde intervensies wat weerstand van HIVkinders en-babas verbeter, positieftoe te pas.