Demonstration of the Dynamic Hypothesis of Latent Tuberculosis Infection

Study Overview
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Brief Summary
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It is traditionally considered that the development of Latent Tuberculosis Infection (LTBI) is due to the M. tuberculosis ability to develop a dormancy state within well-structured lesions (granulomas), which can remain in the lung of the host even for life. A new original hypothesis has been developed in the Experimental Tuberculosis Unit based on scientific evidence that take into account the idea that a lesion cannot be held forever, because the host tends to remove any lesion in order to rebuild the original parenchyma, in a healing process. Even if M. tuberculosis can remain in a dormant/non-replicating state for a long period, this is an important but not sufficient factor to explain the LTBI. The Dynamic Hypothesis tries to explain the existence of LTBI in spite of the healing process that could remove it by a constant reinfection of the host's tissue. While the Static view defends the induction of active TB after the reactivation of the bacilli from and old lesion; while the Dynamic view wants to demonstrate that there is a constant induction of new granulomas. In case one of these new lesions takes place in the upper lobe privileged zone, the possibility to induce a cavity would appear, developing an active Tuberculosis (TB).

Official Title
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Demonstration of the Dynamic Hypothesis of Latent Tuberculosis Infection

Conditions
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Latent Tuberculosis Infection

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: being at least 18 years old to be M.tuberculosis infected (diagnosed by a positive TST with or without a positive result in the QuantiFeron-TB-Gold In tube assay) Exclusion Criteria: active TB individuals not willing to participate in the study and or not willing to sign the informed consent form individuals not able to decide their participation in the study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| 1<br>Patients with LTBI recently diagnosed under prophylactic chemotherapy treatment. | |
| 2<br>Patients with LTBI recently diagnosed not following any prophylactic chemotherapy treatment. | |
| 3<br>Patients with LTBI diagnosed time ago. | |
| 4<br>Positive control for the Exhaled Breath condensate assay only. Patients with active TB will conform this group. The n of this group is determined, as it will only be used as a positive control to prove the bacilli's DNA can be detected in the exhaled breath condensate. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| QuantiFeron-Gold-In Tube method assay |  | Every 6 months during 3 years | 
| Detection of M.tuberculosis DNA and RNA in the exhaled breath condensate |  | Once every year (every 6 months if possible), during 3 years |