Millions of people in the world, according to WHO, suffer from tuberculosis. At the same time, it often has a latent, that is, a latent course, due to which a person easily spreads the infection without knowing it. And therefore, it is extremely important to detect pathology in time, especially since todayin world there are many different systems and tests that help determine the presence of Koch’s bacillus in humans. Moreover, one of them – the recombinant tuberculosis allergen – was included in the WHO recommendations for the world medical community. How is tuberculosis determined today, told Head of the Department of Pediatric and Adolescent Tuberculosis of the National Research Center for Phthisiopulmonology and Infectious Diseases of the Ministry of Health of Russia, Doctor of Medical Sciences, Professor, Honored Doctor , Chief Freelance Pediatric TB Specialist of the Ministry of Health of Russia Valentina Aksenova.
Types of tests
Today, both skin and laboratory tests are used to detect infection early. The first include the well-known Mantoux test and Diaskintest. The second group includes T-SPOT.TB and the quantiferon test, explains Valentina Aksenova. Such tests are used strictly according to the regulations approved by the Russian Ministry of Health. “In children under the age of seven, the Mantoux test is used as a screening for tuberculosis, in children older than this age, Diaskintest. For those children who have a weakened immune system or have certain contraindications for skin tests, the use of a laboratory test is provided, for example, using T-SPOT.TB,” says Valentina Aksenova.
What is the difference?
The Mantoux test, also known as the tuberculin test, has been known for a long time – it has been used in the world for more than 100 years. Until recently, mass diagnostics of such a plan was the only way to test for tuberculosis among children. But at the same time, it has a certain disadvantage. “A positive Mantoux test can be assessed as a sign of a tuberculosis infection that requires immediate treatment, but it can also be a reaction to the BCG vaccination made in the maternity hospital and the developed post-vaccination immunity. At the same time, she cannot determine exactly the immune response to Mycobacterium tuberculosis,” says Valentina Aksenova.
Since 2009, when a fundamentally new diagnostic drug Diaskintest was developedin world, such testing has also been carried out for children. This is a diagnostic system that generates a delayed-type hypersensitivity reaction. At the injection site, a papule (seal on the skin) is formed if the body has an immune response to Mycobacterium tuberculosis. The infectious agent has two antigen proteins in its structure, which are not present in vaccine mycobacteria (from BCG vaccination) and non-tuberculous pathogens. “A papule can be used to assess whether a person has tuberculosis in both the active and latent phases. If it is, a thorough examination is required. If there are no reliable signs of the disease, then such a papule is regarded as an indication of a latent form of tuberculosis, which risks becoming active in the near future. This means that it is necessary to carry out special treatment with a preventive purpose, ”explains Valentina Aksenova.
T-SPOT.TB is another modern diagnostic method. With its help, the presence of a latent infection is checked by blood. If it contains cells that produce interferon-gamma in response to the presence of a pathogen in the body, then it is worth conducting an in-depth examination and starting prevention.
“The Mantoux test today is mainly used to check the child’s reaction to the BCG vaccine and the need to vaccinate him again. Modern tests determine the immune response to the bacillus and help assess the need for additional examinations and treatment,” emphasizes Valentina Aksenova.
Modern tests are unique in that they show a reaction only when the infection is present in the body, that is, they are highly sensitive. “The sample will become positive with a probability of almost 100% and is highly specific, due to which its positive indicators are more likely to indicate tuberculosis, and not something else. Due to the use of such modern test systems, it was possible to reduce by dozens of those who received anti-tuberculosis drugs unreasonably,” says Valentina Aksenova.
The rule “Do not wet your hand if there is Mantu” is well remembered by everyone whose childhood was spent in the USSR. And what recommendations are relevant today and is it really not necessary to wet your hand until the result of the test is evaluated?
“Skin tests are carried out only after examining the child. This should be done by a health worker who has access to conduct such tests. Testing for the Mantoux reaction should be carried out only in completely healthy children, that is, symptoms of malaise are a reason to postpone diagnosis.
After setting Diaskintest, it is necessary to ensure that irritating substances do not get into the place of the sample – this is both sea water and water from the pool. This is due to the fact that itching may begin due to irritants, and the child will simply comb everything. All this can affect the interpretation of the result,” says Valentina Aksenova.
As for the ingress of water drops on the skin test area, they will not affect the result in any way. You can wash, but you can not rub and comb.
“For children who suffer from allergies, it is recommended to perform a test using allergy medications,” notes Professor Aksenova.
Immunological tests are recommended to be carried out at least once a year. However, there are certain risk groups that require more frequent examinations. These include:
- children not vaccinated at the maternity hospital;
- children with reduced immunity, that is, those who have autoimmune conditions and those who receive long-term hormonal and immunosuppressive (immune suppressive) therapy, children born to HIV-infected mothers;
- those with long-term illnesses.
The risk group is recommended to be tested for tuberculosis twice a year, warns Valentina Aksenova.