How does TB spread?
Transmission of TB is by inhalation of infectious droplet nuclei containing viable bacilli (aerosol spread). Mycobacteria-laden droplet nuclei are formed when a patient with active pulmonary TB coughs and can remain suspended in the air for several hours. Sneezing or singing may also expel bacilli.
What is the role of T cells in mycobacteria?
The crucial role of T-cells in immunity to mycobacteria is evidenced by the dramatically increased susceptibility of individuals with HIV infection.
Does vitamin D help with tuberculosis?
The role of vitamin D in susceptibility to tuberculosis also an area which has seen a resurgence of interest and new evidence emerging that targeted vitamin D therapy may have a role in improving TB outcomes. In this section the different phases of infection with Mycobacterium tuberculosis will be reviewed.
What is the role of dendritic cells in the immune system?
Dendritic cells are an important mediator between the innate and adaptive immune response which in addition to phagocytosis, present live mycobacteria to naïve T cells after migrating to regional lymph nodes. After antigen presentation in lymph nodes, CD4+ T cells are activated, and migrate to the lungs to impede mycobacterial progressive growth. ...
What is the role of T cells in immunity?
The crucial role of T-cells in immunity to mycobacteria is evidenced by the dramatically increased susceptibility of individuals with HIV infection. Susceptibility to TB increases as the CD4 cell count decreases. IFN-γ, produced by activated T-cells, has a crucial role in protection against TB.
What is the role of TNF- in macrophages?
TNF-α is another key cytokine produced by macrophages, dendritic cells and T cells and plays a central role in granuloma formation, macrophage induction and has immunoregulatory properties . Patients using TNF suppressing agent are at increased risk of infection and reactivation.
Which cell recognizes mycobacterial structures?
Macrophages, dendritic cells and other immune cells recognize mycobacterial structures, pathogen associated molecular patterns (PAMPs) with membrane associated pattern recognition receptors (PRRs), of which the most studied are the Toll-like receptors (TLR2, TLR4, TLR9).
What is the classification system for TB?
The current clinical classification system for TB used in the United States is based on the pathogenesis of the disease (Table 2.8). It is intended mainly as an operational framework for public health programs. This classification system provides clinicians the opportunity to track the development of TB in their patients. Health-care providers should comply with state and local laws and regulations requiring the reporting of TB disease. All persons with Class 3 (clinically active) or Class 5 (TB suspected) TB should be reported promptly to the local or state health department. A patient should not have a Class 5 classification for more than 3 months.
Where does TB occur?
Extrapulmonary TB disease occurs in places other than the lungs, including the larynx, the lymph nodes, the pleura, the brain, the kidneys, or the bones and joints. In HIV-infected persons, extrapulmonary TB disease is often accompanied by pulmonary TB. Persons with extrapulmonary TB disease usually are not infectious unless they have 1) pulmonary disease in addition to extrapulmonary disease; 2) extrapulmonary disease located in the oral cavity or the larynx; or 3) extrapulmonary disease that includes an open abscess or lesion in which the concentration of organisms is high, especially if drainage from the abscess or lesion is extensive, or if drainage fluid is aerosolized. Persons with TB pleural effusions may have underlying pulmonary TB that is masked on chest radiograph because the effusion fluid compresses the lung. These patients should be considered infectious until pulmonary TB disease is excluded.
How is M. tuberculosis transmitted?
Infectious droplet nuclei are generated when persons who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing. Depending on the environment, these tiny particles can remain suspended in the air for several hours. M. tuberculosis is transmitted through the air , not by surface contact. Transmission occurs when a person inhales droplet nuclei containing M. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli of the lungs (Figure 2.2).
Where do tuberculosis bacilli spread?
A small number of tubercle bacilli enter the bloodstream and spread throughout the body. The tubercle bacilli may reach any part of the body,including areas where TB disease is more likely to develop (such as the brain, larynx, lymph node, lung, spine, bone, or kidney).
How many people with TB will develop TB?
Without treatment, approximately 5% of persons who have been infected with M. tuberculosis will develop disease in the first year or 2 after infection, and another 5% will develop disease sometime later in life. Thus, without treatment, approximately 10% of persons with normal immune systems who are infected with M. tuberculosis will develop TB disease at some point in their lives.
Is TB pulmonary or pulmonary?
TB disease most commonly affects the lungs; this is referred to as pulmonary TB. In 2011, 67% of TB cases in the United States were exclusively pulmonary. Patients with pulmonary TB usually have a cough and an abnormal chest radiograph, and may be infectious. Although the majority of TB cases are pulmonary, TB can occur in almost any anatomical site or as disseminated disease.
Where does extrapulmonary TB occur?
Extrapulmonary TB disease occurs in places other than the lungs, including the larynx, the lymph nodes, the pleura, the brain, the kidneys, or the bones and joints. In HIV-infected persons, extrapulmonary TB disease is often accompanied by pulmonary TB. Persons with extrapulmonary TB disease usually are not infectious unless they have 1) pulmonary disease in addition to extrapulmonary disease; 2) extrapulmonary disease located in the oral cavity or the larynx; or 3) extrapulmonary disease that includes an open abscess or lesion in which the concentration of organisms is high, especially if drainage from the abscess or lesion is extensive, or if drainage fluid is aerosolized. Persons with TB pleural effusions may have underlying pulmonary TB that is masked on chest radiograph because the effusion fluid compresses the lung. These patients should be considered infectious until pulmonary TB disease is excluded.
Is tuberculosis a disease?
Tuberculosis (TB) is an infectious bacterial disease caused by Mycobacterium tuberculosis. Despite global TB eradication efforts, it is still a global public health concern, especially in low- and middle-income countries. Most of the active TB infections are curable with early diagnosis and appropriate treatment, but drug-resistant TB is difficult and expensive to treat in immunocompetent as well as immunocompromised individuals. Thus, rapid, economic, and accurate point-of care tools for TB diagnosis are required urgently. This review describes the history of M. tuberculosis detection methods up to date and the recent advances using nanotechnology for point-of-care testing of TB diagnosis.
What is MPDS TB?
Molecular Property Diagnostic Suite (MPDS TB ) is a web tool (http://mpds.osdd.net) designed to assist the in silico drug discovery attempts towards Mycobacterium tuberculosis (Mtb). MPDS TB tool has nine modules which are classified into data library (1–3), data processing (4–5) and data analysis (6–9). Module 1 is a repository of literature and related information available on the Mtb. Module 2 deals with the protein target analysis of the chosen disease area. Module 3 is the compound library consisting of 110.31 million unique molecules generated from public domain databases and custom designed search tools. Module 4 contains tools for chemical file format conversions and 2D to 3D coordinate conversions. Module 5 helps in calculating the molecular descriptors. Module 6 specifically handles QSAR model development tools using descriptors generated in the Module 5. Module 7 integrates the AutoDock Vina algorithm for docking, while module 8 provides screening filters. Module 9 provides the necessary visualization tools for both small and large molecules. The workflow-based open source web portal, MPDS TB 1.0.1 can be a potential enabler for scientists engaged in drug discovery in general and in anti-TB research in particular.
What is the hallmark of tuberculosis?
Here, monocytes from nearby blood vessels form the beginning of a granuloma, as the immune system attempts to ward off the disease. This is a hallmark characteristic of tuberculosis. Within the granuloma, a core of infected macrophages is surrounded by foamy macrophages, mononuclear phagocytes, and lymphocytes.
How long does it take for TB to show up on a skin test?
After three to eight weeks , despite widespread infection, there are no immediate symptoms or signs other than a positive TB skin test (TST). In children, the elderly, non-white races, and AIDS patients, the disease progresses quickly to pneumonia from hilar or mediastinal lymph nodes to cavitation in the bronchi.
How long does it take for a skin test to show a latent infection?
In general, hypersensitivity develops during the three-to-eight week period after infection, signaling the action of cellular immunity and control of the infection. At this time, a skin test reaction will be positive indicating latent infection exists.
