Active clinical trials for "Latent Tuberculosis"

Hypothesis: a combined strategy of tuberculin skin test (TST) followed by QuantiFERON-TB Gold In-Tube (QFT-IT) to confirm positivity (tuberculosis infection,in contact-tracing study will allow avoiding unnecessary preventive treatment without increasing rates of tuberculosis cases among contacts screened. Aim of the study: to compare a combined strategy of the TST and the QFT-IT with TST alone for the diagnosis of tuberculosis infection and for therapeutic decision in contact tracing study. Design and setting: Prospective, multicentre, comparative study in 12 hospitals in Spain. Study population: 870 subjects, household contacts of patients with culture positive pulmonary and/or laryngeal tuberculosis will be randomized to one of two strategies: Arm A (standard practice), in which treatment decisions will be based on the TST result, and Arm B (experimental), in which treatment decisions will be based on the QFT result. Interventions: participants in arm A will undergo TST; participants in arm B will undergo TST, and, in case of a positive result, QFT-IT as well. Participants with positive TST (arm A) and positive QFT-IT (arm B) will be diagnosed with tuberculosis infection and will be treated with isoniazid for 6 months. All participants will be followed for two years. End-points of evaluation: development of tuberculosis and proportion of subjects for whom treatment is prescribed in each arm.

The purpose of this study is to evaluate whether isoniazid can safely (and further) reduce the risk of tuberculosis in HIV infected people receiving HAART.

In populations with high prevalence of latent tuberculosis infection (LTBI), malnutrition (PEM) may influence incident rates of TB. PEM and specific micronutrient deficiencies compromise cell mediated immunity (CMI) and increase susceptibility to, or severity of infections. Vitamin A supplementation significantly reduces all-cause child mortality. The mechanism of the benefits of supplementation on clinical outcomes is largely unknown, but is likely to be related to an influence on the immune system. Vitamin A supplementation promotes lymphogenesis and induces a higher proportion of CD4 naïve T-cells in children. Most cases of LTBI that progress to active disease are vitamin A deficient. Vitamin A deficiency is common in most TB endemic countries. At the MRC, 32% of TBCC contacts were vitamin A deficient. Hypothesis: The investigators plan to test the hypotheses: that supplementation with vitamin A will affect the magnitude and quality of immune responses to mycobacterial antigens and progression to clinical disease.

Dose comparison study of tuberculin purified protein derivative (PPD)Aplisol with the standard tuberculin purified derivative (PPD-S2).

Tuberculosis burden in Vietnam increasing with contribution from low detection rates and increased drug resistance. There is a need to identify MDR-TB (MultiDrug Resistant Tuberculosis) among both notified TB cases and their contacts in the community. Traditional contact tracing often focuses on household contacts while strains of TB circulate in homes, schools, workplaces, and beyond. Social network Analysis (SNA) is a comprehensive approach which includes a set of persons and the connections among them used for analysis of structure of disease transmission. In this study, SNA will be used to collect network data from 60 newly detected Rifampicin resistant TB patients including an expected 50 MDR-TB patients living in Hanoi, and to identify and test potential MDR-TB cases.

Primary Objective: 1. To evaluate the performance of the new T-SPOT.TB test and the conventional TST for screening of Latent Tuberculosis infections in patients with cancer and those undergoing Hematopoietic Stem Cell Transplant. Secondary Objectives: To examine the factors associated with positive response to T-SPOT.TB and the TST (tuberculin skin test) in patients with anergy. To determine the impact of immunosuppressive and antineoplastic therapy on the screening performance of T-SPOT.TB and the TST in cancer patients.

Detection of M. tuberculosis in clinical specimens of children has a low sensitivity because specimens are either difficult to collect or contain low levels of M. tuberculosis. Diagnostic criteria are non-specific and culture confirmation is challenging, as sputum samples are not often obtainable from small children and specimens typically have low yield. Although children are typically thought to have paucibacillary disease, they are at greater risk for dissemination of TB. This may allow for detection of Mycobacterium tuberculosis from other bodily fluids than sputum or gastric aspirate, including blood and urine. Unfortunately, little is known about the overall yield from these various specimens. From pilot data collected among adults and children in Tugela Ferry, we know that it is feasible to collect and test various bodily fluid specimens for TB culture. This study aim to test the hypothesis that blood and urine cultures will detect Mycobacterium tuberculosis from children suspected of disseminated TB, and that a proportion of these non-sputum bodily fluids will detect both drug-susceptible and drug-resistant tuberculosis when sputum or gastric culture does not.

This study will examine how the immune system responds to infection with Mycobacterium tuberculosis bacteria (bacteria that cause tuberculosis) in order to better understand how the germ produces infection and how the immune response might work to control the infection. Only about one in 10 people infected by M. tuberculosis become sick, sometimes years or even decades after exposure. It is not known why some people become sick and most do not, but the immune system of people who never develop disease may be better able to control the bacteria. This study will evaluate the latent form of M. tuberculosis infection to further the understanding of the immune mechanisms - particularly the role of certain white blood cells - involved in the disease process. Healthy volunteers 18 years of age and older may be eligible for this study. Candidates are screened with a medical history, family history of medical conditions, sexual history, history of drug use, physical examination and blood tests, including a test for HIV. People in Mali, West Africa, and in local health clinics in the United States may participate. At the start of the study, participants have blood tests and a tuberculin skin test (PPD test), which indicates whether a person has been exposed to tuberculosis bacteria. For the PPD, a tiny amount of liquid containing dead tuberculosis antigen is put under the skin of the forearm with a needle. The antigen cannot cause infection or disease. After 3 days, participants have another blood test and the site of the tuberculin test is examined for swelling that would indicate a positive result. Participants with a positive PPD have a chest x-ray to check for tuberculosis disease. Those whose x-ray is also positive are withdrawn from the study and referred to their doctor for evaluation and treatment. Those whose x-ray is negative return to the clinic within 3 weeks of the tuberculin test to give another blood sample. Participants whose PPD is negative have a second tuberculin test 10 to 21 days later and return 3 days after the test to determine if it is still negative or if it is positive. (Some people who are negative after the first test may test positive after the second procedure.) Those whose test is still negative end their participation in the study at that time. Participants whose second PPD is positive have a chest x-ray as described above, and those with a negative chest x-ray return in 3 weeks to donate one last blood sample. The purpose of the present study is to evaluate the latent form of this infection, the prevalence of which worldwide exceeds that of active disease. Our hypothesis is that in latent tuberculosis antigen specific effector memory CD4+ T cells are responsible for the generation of clinically measurable delayed type hypersensitivity and that central memory CD4+T cells are not directly involved in this process. We base this idea on the assumption that latent tuberculosis is a state of antigen persistence and that effector memory T cells should be maintained as long as antigen/infection is present. We propose to conduct this study in Mali, West Africa and local clinics in the U.S. Tuberculosis affects 593/100,000(2) individuals in Mali and most have been exposed to the disease. Additionally it would be important to evaluate the same parameters locally as latent infection is one of the major factors for reactivation tuberculosis in this country. Patients would be enrolled in 4 major groups: HIV-/TST- (Group A), HIV-/TST+ (Group B), HIV+/TST+(G roup C) and HIV+/TST- (Group D). To evaluate this hypothesis we plan to enroll between 100 - 300 patients over the course of 2 years from both countries. Blood samples before and at predetermined time points after the application of Purified Protein Derivative (PPD) will be obtained to determine the fraction of CD4+ T cells which produce interferon gamma in response to stimulation with PPD with a 16hr antigen stimulation assay. Appropriate staining will be done to ascertain the phenotype as well as cytokine production (Interferon gamma,( IFN gamma), Interleukin 2 (IL2) and Tumour Necrosis Factor ( TNF)). Additionally lymphocyte proliferation will be studied using 5-(and-6)-carboxyflouorescein diacetate succinimidyl ester (CFSE.) In conducting this study we hope to further the understanding of the immune mechanisms involved, particularly mechanisms of T cell memory, which would provide insights into TB and HIV pathogenesis. We also believe that understanding these mechanisms could lead towards establishment of surrogates for immunity in TB vaccine studies, which could enhance vaccine trial design. It might also help in understanding better the immunological dynamics of tuberculosis co-infection in individuals with HIV infection.

Study Design: Stratified, matched, cluster-randomized, controlled trial Unit of Randomization: Healthcare facility Study Duration: 3 years; prevalence of latent Tuberculosis infection (LTBI) in healthcare workers (HCWs) will be at measured at baseline, and LTBI incidence will be measured among susceptible HCWs at 12 and 24 months. Secondary outcomes will be measures at 0 (pre-intervention) 6, 12, 18, and 24 months. In year three, results will be analyzed and disseminated. Study Components: Assessment of institutional safety culture; observations/audits of Tuberculosis (TB) patient flow (wait times) and HCW TB infection control (IC) practices; documentation of time intervals for processing sputum smears and initiation of TB treatment; facility assessments; random allocation and implementation of enhanced Tuberculosis infection control (TB IC) package; testing of HCWs to determine LTBI at 0, 12, 24 months; cost evaluation of intervention. Sample Size: For the cluster randomized design, we estimate that 11 clusters per group will allow for 77 percent (%) power to identify a 30% reduction in LTBI incidence in the intervention vs. control clusters. This assumes LTBI incidence 5% per year in the control group, design effect for clustering of 2.0, and cluster size of 300 (average 600 HCW per cluster with 50% LTBI prevalence at baseline).

Background: The TB and HIV epidemics are closely linked in developing countries, where 450,000 children die from HIV annually. TB is a major cause of death in HIV-infected children and is reversing gains made in child survival. The traditional tuberculin skin test (TST) has limited diagnostic accuracy for detecting TB infection. Adult studies suggest that new blood-based diagnostic TB testing offers a quicker, more accurate way to diagnose TB infection. Such diagnostic testing may directly guide clinical management and preventive strategies in immune-suppressed HIV-infected children, who are at high risk of becoming TB diseased following infection. Data regarding the usefulness of these tests in children is currently limited. Objective(s) and Hypothesis(es): The investigators hypothesize that blood-based TB diagnostic testing can accurately identify children with TB infection. In a community with high rates of TB and HIV infection, the following specific aims will be investigated in HIV-infected and uninfected children: assess the agreement between the TST and blood-based diagnostic testing, compare the performance of the TST and blood-based diagnostic testing to a standardized history of TB exposure, measure the impact of age, nutritional and immune status on children's response to blood-based testing, describe factors that might modify children's response to testing over time, and 5) examine the effect of environmental exposures and previous vaccination on the TST, blood-based testing and other measures of immune responses to TB. Potential Impact: The benefits of an accurate, rapid diagnostic test of TB infection in children include 1) timely institution of treatment for TB infection to prevent severe disease and mortality, and 2) preclusion of over diagnosis and treatment. Treatment of childhood TB infection also prevents future contagious adult disease, thus decreasing community transmission. Blood-based diagnostic testing may also be able to identify children that are more likely to become ill following TB infection. Therefore, blood-based diagnostic testing has great potential to improve TB control and the health of HIV-infected and uninfected children, their households and communities.