Common questions about Диаскинтест (FAQ)
Q: Can the Diaskintest injection site get wet?
Official regulatory guidance advises that the injection site must remain undisturbed and unbandaged until the results are assessed, which occurs 72 hours after administration. While specific instructions on showering or water contact are often omitted, the guidance emphasizes protecting the area from any friction, rubbing, or excessive moisture that could interfere with the accurate reading of the immune response.
Q: What happens if I wash my hand or the test site after Diaskintest?
The official instruction is to keep the test site undisturbed and free of rubbing. While washing the hand is generally considered acceptable, regulatory guidance emphasizes that contact with the injection site on the forearm should be avoided to prevent friction or disturbance until the official measurement at 72 hours.
Q: Can I exercise after the test?
Regulatory instructions require the injection site to remain undisturbed until the final assessment. Activities that may cause significant friction, rubbing, or trauma to the injection site, such as heavy exercise or strenuous sports, are often discouraged to ensure the integrity of the test site is maintained until the result is read.
Q: How does Diaskintest differ from the Mantoux test?
Diaskintest is an immunological diagnostic agent that uses two specific recombinant proteins (ESAT-6 and CFP-10) to target a highly specific immune response. In contrast, the Mantoux (Tuberculin Skin Test) uses Purified Protein Derivative (PPD), which is less specific and can sometimes show a reaction due to prior BCG vaccination.
Q: Why is Diaskintest considered more specific/accurate?
The recombinant proteins used in Diaskintest (ESAT-6 and CFP-10) are specifically characteristic of virulent Mycobacterium tuberculosis but are absent in the BCG vaccine strain. This composition is intended to provide high diagnostic specificity, which aids in differentiation between a true infection and the immune response resulting from a prior BCG vaccination.
Q: Can Diaskintest give a false-positive result?
As with many diagnostic tests, there is a potential for inaccurate interpretation or an unexpected result. The specific antigens in Diaskintest are designed to reduce the false-positive rate compared to Mantoux in BCG-vaccinated individuals, but incorrect measurement or interpretation remains a potential cause of error.
Q: What reaction to Diaskintest is considered normal (negative)?
The 'normal' or negative reaction is the absence of a significant immunological response. Official guidelines define a negative result based on the size (in millimeters) of the resulting induration, which should fall below a defined threshold, as determined by a healthcare professional.
Q: What does a 'positive reaction' mean?
A positive reaction means the body’s immune system has recognized the recombinant proteins, resulting in a measurable induration (localized skin thickening and hardening) that exceeds the defined threshold. This result suggests the presence of a Mycobacterium tuberculosis infection.
Q: When is the best time to do Diaskintest?
The test must be performed when the individual is generally healthy and not experiencing an acute infectious disease or a flare-up of a chronic disease, as these can interfere with the results. It is also subject to specific timing requirements, such as waiting at least one month after any prophylactic vaccination.
Q: How often can Diaskintest be done?
The test is administered only when there is a clinical indication for screening or follow-up evaluation. There are no official recommendations for routine annual testing unless the individual belongs to a high-risk group or has had a recent exposure that requires re-assessment.
Q: What should I do if the injection site is itchy?
Itching (pruritus) at the injection site is listed in regulatory documentation as a common local adverse reaction. The site must remain undisturbed and should not be scratched or rubbed. Any persistent or unusually severe irritation should be reported to the healthcare professional performing the final assessment.
Q: Can Diaskintest cause a fever?
Yes, regulatory documents list systemic symptoms such as fever (pyrexia), weakness, and chills as possible adverse reactions following administration of the diagnostic agent.
Q: Can I eat certain foods before the test?
Official regulatory documentation for this diagnostic agent does not list any specific restrictions or requirements regarding food or fasting before the test procedure. Preparation is generally limited to timing relative to illness and other immunological interventions.
Q: Can Diaskintest be done during a cold?
No, the test is absolutely contraindicated (officially restricted) during acute infectious diseases, which includes the common cold (proстуда). The presence of a systemic infection can potentially interfere with the required immunological response and test validity.
Q: Does allergy affect the result of Diaskintest?
Yes, non-specific allergy can potentially interfere with the diagnostic result. Official instructions describe the use of desensitizing preparations, such as antihistamines, for a specified period around the test date for individuals with a known history of non-specific allergy, to manage potential interference.
Q: Can the test be done if a child has asthma?
The test is contraindicated if the individual has chronic diseases (such as asthma) that are currently in the stage of exacerbation (a flare-up). The test may be performed during stable, non-exacerbated periods of a chronic disease.
Q: How long after BCG vaccination can Diaskintest be done?
The official temporal restriction states that the test must be postponed if the individual is within one month of any prophylactic vaccination, including the BCG vaccine. This waiting period is necessary to ensure the vaccination does not interfere with the immunological response needed for an accurate test result.
Q: Do hormonal drugs affect the result?
The regulatory profile specifically cautions that the use of immunosuppressive agents can depress the immune response, which may affect the test outcome. This category of drugs includes high-dose or long-term systemic corticosteroids, which are hormonal preparations. Other hormonal drugs, such as birth control, are generally not listed as contraindications.
Q: How is the result checked—is it redness or only the papule/induration?
The official interpretation relies on measuring the diameter of the induration (the localized skin thickening and hardening), not the erythema (redness). The induration is the visible manifestation of the underlying cellular T-cell mediated response, which is the key diagnostic sign.
Q: What is a 'doubtful' result?
The result is officially classified as 'doubtful' when the induration measurement falls within a specific range defined in the regulatory guidelines. This result is neither clearly negative nor clearly positive, and it indicates the need for further clinical evaluation or follow-up testing.
Q: How long after administration does the result become invalid?
The skin reaction must be officially measured and evaluated exactly 72 hours after administration. If the reading is performed significantly later than the required time window, the diagnostic reaction may have subsided, potentially rendering the result uninterpretable and invalid.
Q: Why isn't Diaskintest given to everyone?
The test is not performed on everyone due to official regulatory Absolute Contraindications. These restrictions include, but are not limited to, acute infectious diseases, chronic diseases in the stage of exacerbation, epilepsy, widespread skin diseases, and known hypersensitivity to the components of the solution.
Q: Is it true that it is primarily done only in Russia?
Diaskintest is specifically manufactured in Russia and is primarily used under Russian regulatory guidelines. However, the core methodology, which uses ESAT-6 and CFP-10 recombinant antigens, is the foundation for internationally recognized diagnostic blood tests (Interferon-Gamma Release Assays or IGRA).
Q: Can I take antihistamines before the test?
Official regulatory instructions describe that for individuals with a history of non-specific allergy, the test is sometimes conducted while taking desensitizing preparations (antihistamines) for a specified period (typically 5 days before and 2 days after the test) to manage potential allergic interference.
Q: Can Diaskintest be done if there was recent contact with a sick person?
Yes, the test is specifically indicated for screening individuals who have had close contact with a known TB patient. This is a common and appropriate use case to aid in the detection of Latent Tuberculosis Infection (LTBI).
Q: What is the maximum period between administration and checking?
The reaction must be measured and evaluated between 48 and 72 hours, with 72 hours being the mandatory checkpoint. If a patient returns significantly later, the reaction may have subsided, and the test may need to be repeated because the result would be considered invalid.
Q: What should be done if the test is positive?
A positive result indicates a probable immune response to M. tuberculosis infection. This result is considered an indicator for further medical evaluation, which typically includes diagnostic steps such as a chest X-ray and clinical assessment to determine the status of the infection.
Q: Can there be a bruise at the injection site?
The regulatory profile lists hemorrhage (bleeding) as a possible adverse reaction. While a bruise (hematoma) is not explicitly listed, it may occur as a minor, expected consequence of any intradermal injection and should generally subside on its own.
Q: Is special preparation needed before the procedure?
Special preparation is required regarding the timing of the test relative to recent prophylactic vaccinations and for individuals with a history of allergy, as these can interfere with the results. Outside of these timing-related restrictions, no specific preparation (such as fasting or dietary changes) is noted.
Q: Can Diaskintest be done with chronic diseases?
Yes, the test can generally be performed if the chronic disease is not in the stage of exacerbation (a flare-up). The test is only absolutely contraindicated when the chronic disease is acute or worsening, as this could interfere with the body's immune response.
Q: Is a negative reaction related to immunity?
Yes, a negative reaction is directly related to the immune system. It indicates the absence of a T-cell mediated Delayed-Type Hypersensitivity response, meaning the immune cells (T-lymphocytes) were not previously sensitized to the specific recombinant proteins used in the diagnostic solution.
