Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis (TB). It is named after its inventors Albert Calmette and Camille Guérin. In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as soon after birth as possible. In areas where tuberculosis is not common, only children at high risk are typically immunized, while suspected cases of tuberculosis are individually tested for and treated. Adults who do not have tuberculosis and have not been previously immunized, but are frequently exposed, may be immunized, as well. BCG also has some effectiveness against Buruli ulcer infection and other nontuberculous mycobacterial infections. Additionally, it is sometimes used as part of the treatment of bladder cancer.
Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is an infectious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in which case it is known as latent tuberculosis. Around 10% of latent infections progress to active disease which, if left untreated, kill about half of those affected. Typical symptoms of active TB are chronic cough with blood-containing mucus, fever, night sweats, and weight loss. Infection of other organs can cause a wide range of symptoms.
The Mantoux test or Mendel–Mantoux test is a tool for screening for tuberculosis (TB) and for tuberculosis diagnosis. It is one of the major tuberculin skin tests used around the world, largely replacing multiple-puncture tests such as the tine test. The Heaf test, a form of tine test, was used until 2005 in the UK, when it was replaced by the Mantoux test. The Mantoux test is endorsed by the American Thoracic Society and Centers for Disease Control and Prevention. It was also used in the USSR and is now prevalent in most of the post-Soviet states, although Soviet mantoux produced many false positives due to children's allergic reaction.
Pott's disease, or Pott disease, named for British surgeon Percivall Pott who first described the symptoms in 1799, is tuberculosis of the spine, usually due to haematogenous spread from other sites, often the lungs. The lower thoracic and upper lumbar vertebrae areas of the spine are most often affected.
Isoniazid, also known as isonicotinic acid hydrazide (INH), is an antibiotic used for the treatment of tuberculosis. For active tuberculosis, it is often used together with rifampicin, pyrazinamide, and either streptomycin or ethambutol. For latent tuberculosis, it is often used alone. It may also be used for atypical types of mycobacteria, such as M. avium, M. kansasii, and M. xenopi. It is usually taken by mouth, but may be used by injection into muscle.
The tine test is a multiple-puncture tuberculin skin test used to aid in the medical diagnosis of tuberculosis (TB). The tine test is similar to the Heaf test, although the Mantoux test is usually used instead. There are multiple forms of the tine tests which usually fall into two categories: the old tine test (OT) and the purified protein derivative (PPD) tine test. Common brand names of the test include Aplisol, Aplitest, Tuberculin PPD TINE TEST, and Tubersol.
Tuberculosis is diagnosed by finding Mycobacterium tuberculosis bacteria in a clinical specimen taken from the patient. While other investigations may strongly suggest tuberculosis as the diagnosis, they cannot confirm it.
The lepromin skin test is used to determine what type of leprosy a person is infected with. It involves the injection of a standardized extract of the inactivated "leprosy bacillus" under the skin. It is not recommended as a primary mode of diagnosis.
Tuberculin, also known as purified protein derivative, is a combination of proteins that are used in the diagnosis of tuberculosis. This use is referred to as the tuberculin skin test and is recommended only for those at high risk. Reliable administration of the skin test requires large amounts of training, supervision, and practice. Injection is done into the skin. After 48 to 72 hours, if there is more than a five to ten millimeter area of swelling, the test is considered positive.
Tuberculosis verrucosa cutis is a rash of small, red papules and nodules in the skin that may appear two to four weeks after inoculation by Mycobacterium tuberculosis in a previously infected and immunocompetent individual.
Lupus vulgaris are painful cutaneous tuberculosis skin lesions with nodular appearance, most often on the face around the nose, eyelids, lips, cheeks, ears and neck. It is the most common Mycobacterium tuberculosis skin infection. The lesions may ultimately develop into disfiguring skin ulcers if left untreated.
Latent tuberculosis (LTB), also called latent tuberculosis infection (LTBI) is when a person is infected with Mycobacterium tuberculosis, but does not have active tuberculosis (TB). Active tuberculosis can be contagious while latent tuberculosis is not, and it is therefore not possible to get TB from someone with latent tuberculosis. The main risk is that approximately 10% of these people will go on to develop active tuberculosis. This is particularly true, and there is added risk, in particular situations such as medication that suppresses the immune system or advancing age.
Interferon-γ release assays (IGRA) are medical tests used in the diagnosis of some infectious diseases, especially tuberculosis. Interferon-γ (IFN-γ) release assays rely on the fact that T-lymphocytes will release IFN-γ when exposed to specific antigens. These tests are mostly developed for the field of tuberculosis diagnosis, but in theory, may be used in the diagnosis of other diseases which rely on cell-mediated immunity, e.g. cytomegalovirus and leishmaniasis and COVID-19. For example, in patients with cutaneous adverse drug reactions, challenge of peripheral blood lymphocytes with the drug causing the reaction produced a positive test result for half of the drugs tested.
Interferon-gamma release assays (IGRAs) are diagnostic tools for latent tuberculosis infection (LTBI). They are surrogate markers of Mycobacterium tuberculosis infection and indicate a cellular immune response to M. tuberculosis if the latter is present.
T-SPOT.TB is a type of ELISpot assay used for tuberculosis diagnosis, which belongs to the group of interferon gamma release assays. The test is manufactured by Oxford Immunotec in the UK. It is available in most European countries, the United States as well as various other countries. It was developed by researchers at the University of Oxford in England.
The Fernandez reaction is a reaction that occurs to signal a positive result in the lepromin skin test for leprosy. The reaction occurs in the skin at the site of injection if the body possesses antibodies to the Dharmendra antigen, one of the antigens found in Mycobacterium leprae, the bacteria that causes leprosy. The reaction occurs via a delayed-type hypersensitivity mechanism. This reaction occurs within 48 hours of injection of lepromin and is seen in only tuberculoid forms of leprosy. This represents a delayed-type hypersensitivity reaction. In contrast, the Mitsuda reaction occurs 3–4 weeks after injection of lepromin and is only seen in patients with the tuberculoid form of leprosy. In terms of mechanism of action and appearance, the reaction is similar to the tuberculin reaction of a positive Mantoux test for tuberculosis.
Lichen scrofulosorum is a rare tuberculid that presents as a lichenoid eruption of minute papules in children and adolescents with tuberculosis. The lesions are usually asymptomatic, closely grouped, skin-colored to reddish-brown papules, often perifollicular and are mainly found on the abdomen, chest, back, and proximal parts of the limbs. The eruption is usually associated with a strongly positive tuberculin reaction. Of the three tuberculids, the incidence of lichen scrofulosorum was found to be the lowest (2%) in a large study conducted in Hong Kong. This highlights its rarity and significance as an important marker of undetected tuberculosis.
The antibodies from lymphocyte secretions (ALS) assay is an immunological assay to detect active diseases like tuberculosis, cholera, typhoid etc. Recently, ALS assay nods the scientific community as it is rapidly used for diagnosis of Tuberculosis. The principle is based on the secretion of antibody from in vivo activated plasma B cells found in blood circulation for a short period of time in response to TB-antigens during active TB infection rather than latent TB infection.
The National Tuberculosis Institute (NTIB) is a Government of India institute, under the Directorate General of Health Services, Ministry of Health and Family Welfare, dedicated to advanced research on Tuberculosis. The Institute is located along Bellary Road, in Bengaluru, Karnataka state, India.
Non-specific effects of vaccines are effects which go beyond the specific protective effects against the targeted diseases. Non-specific effects can be strongly beneficial by increasing protection against non-targeted infections. This has been shown with two live attenuated vaccines, BCG vaccine and measles vaccine, through multiple randomized controlled trials. Theoretically, non-specific effects of vaccines may be detrimental, increasing overall mortality despite providing protection against the target diseases. Although observational studies suggest that diphtheria-tetanus-pertussis vaccine (DTP) may be highly detrimental, these studies are at high risk of bias and have failed to replicate when conducted by independent groups.
