Contact investigation Tuberculosis contacts are people who have close contact with patients with infectious TB.
Untreated fibrotic lesions suggesting previous TB in chest X-ray Some patients have no obvious predisposing factors and may just be naturally susceptible to progression.
First, a unique cell wall structure with high lipid content protects the bacterium from the highly acidic pH of the phagosome. Second, it is able to arrest phagosome—lysosome fusion.
Host Factors As described above, the human immune response against the MTC includes both the innate defense system macrophage and natural killer cells, complement activation, ciliary clearance, and secretions of the main airways and the adaptive response, comprising both cellular and humoral immunity.
T cells are the main component of the cellular response that provides protection against TB and promotes memory response and granuloma formation.
Although historically B cells and humoral immunity were not considered to offer any protection, some studies have shown they do contribute to immunological control Gupta et al. The main benefit of the adaptive response is the presence of immunological memory, so that a copy of each antigen found is stored in memory T cells and will lead to a rapid and enhanced response to subsequent encounters with that same antigen.
This is the basis for the TST, a delayed-type hypersensitivity reaction caused by cytokines released from previously sensitized T cells when they are exposed to PPD antigens. Although hypersensitivity is linked to protective immunity, protection is not complete.
Different studies have shown that TST-positive reactors are less likely to be reinfected than nonresponders, but there is no way to prevent reactivation without specific treatment.
From 2 to 4 wk after the first encounter between bacteria of the MTC and macrophages, the human host prepares two types of responses.
The first one is delayed-type hypersensitivity to tubercle bacilli, which is tissue damaging as it promotes destruction of nonactivated macrophages containing proliferating mycobacterium.
The second is a cell-mediated response, which activates macrophages to kill bacteria. There is a dynamic equilibrium between these two responses, which can lead to either TB progression or containment of MTC.
The disease, preventable and treatable, has been grossly neglected and no country is immune to it. Subsequent steps include screening for clinically asymptomatic LTBI in high-risk populations.
In addition to effective active TB control, the post WHO global TB strategy recognizes that elimination requires a focus on reducing the pool of latently infected individuals from which future TB cases would be generated.
These include recently infected persons, immunocompromised individuals such as HIV human immunodeficiency virus patients, anti-TNF and transplant candidates, and household contacts of pulmonary TB cases.
Additionally, health-care workers and migrants from high-incidence countries to low-incidence settings may be tested and given preventive treatment. Although a variety of approaches have been used, the Mantoux technique, which is administered on the inner surface of the forearm, is one of the most widely used globally.
The standard doses are 5 PPD units 0. Both types of tuberculins contain a complex mixture of antigens, including those of M.
Tuberculin will stimulate a delayed-type hypersensitivity response via T lymphocytes. A positive TST can be detected by an induration on the site of injection after 48—72 h. The result is the transverse diameter of the induration, which is usually recorded in millimeters.
The interpretation of the result should take into account immunosuppression as well as the prevalence of TB in the setting in question—5 mm is considered positive if the patient is immunosuppressed, but it will be considered negative in healthy patients living in high-prevalence areas, for whom a mm cutoff will apply.
In some settings, a uniform cutoff of 10 mm is applied. These different and subjective considerations make it difficult to compare TST properties between studies in different countries and populations. There are also other drawbacks in this apparently simple test. In subjects with chronic debilitating conditions or immunosuppression, TST may have a lower sensitivity than in healthy people.
It must be administrated and read by trained professionals so as to avoid variability of the results. It also requires two clinical visits, and a positive reaction may interfere with confidentiality issues.
Two IGRAs have been developed: QFT also includes a third antigen, TB7.Tuberculosis (TB) poses a serious threat to public health throughout the world but disproportionately afflicts low-income nations.
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If a person is found to be infected with TB bacteria, other tests are needed to see if the person has latent TB infection or TB disease.
DIAGNOSIS AND MANAGEMENT OF TUBERCULOSIS IN THE Tuberculosis could be transmitted antepartum. Chapter 5 Diagnosis and Management of Tuberculosis Tuberculosis and its Diagnosis: A Review Abdul Jabbar Assistant Professor, Department of Medical Lab Technology, University of Haripur, Haripur.
Tuberculosis: Clinical Diagnosis and Management of Tuberculosis, and Measures for Its Prevention and Control. National Collaborating Centre for Chronic Conditions (UK); Centre for Clinical Practice at NICE (UK).