Laboratory diagnostics in children with perinatal contact for HIV infection
Most children born to HIV-infected mothers have antibodies to HIV in their blood (mothers). In this regard, serological methods of diagnosing HIV infection, based on the definition of IgG antibodies (ELISA), are not diagnostically significant up to 18 months of life, when the maternal antibodies are completely destroyed.
Own specific antibodies appear in the child in 90-95% of cases within 3 months after infection, in 5-9% - after 6 months and in 0,5% - later. In children older than 18 months, the detection of serological markers is considered diagnostic.
Planned serological tests are performed at birth, at 6; 12 and 18 months of life. Getting two or more negative results at intervals of at least 1 month in a child without hypogammaglobulinemia at the age of 12 months and older is indicative of HIV infection.
In children 18 months and older, in the absence of HIV infection and hypogammaglobulinemia, a negative serological test for antibodies to HIV can eliminate HIV infection.
Molecular biological methods allow to reliably confirm HIV infection in the majority of infected newborns by the age of 1 month and practically in all infected children by the age of 6 months.
The detection of HIV DNA by PCR is the preferred method for diagnosing HIV infection in young children. Among the perinatally infected positive result of PCR, 38% of children are in the first 48 hours of life, and at the age of 14 days - 93% of children. Chemoprophylaxis does not reduce the sensitivity of virological tests.
The first mandatory examination is carried out at the age of 1-2 months, the second - after 1 month. When receiving a second positive result, it is necessary to determine the viral load (i.e., the number of copies of HIV RNA in 1 ml of plasma) in a quantitative manner, which makes it possible to assess the risk of disease progression and the adequacy of antiretroviral therapy.
Children with negative results at birth and at the age of 1-2 months should be examined again at the age of 4-6 months.
One of the additional methods of examining an HIV-infected child is the evaluation of the immune status, namely, the determination of the percentage and the absolute number of CD4 + T-lymphocytes.
After obtaining a positive result of HIV nucleic acids, a quantitative study of CD4 + and CD8-lymphocytes in a child is necessary, preferably by flow cytometry. The study should be carried out regularly every 3 months (2-3th immune category) or 6 months (1st immune category).
When a change in the immunological profile is detected (CD4 + cells <1900 / mm 3 and CD8-cells> 850 / mm 3 ), the child of the first 6 months of life assumes a rapidly progressive form of the disease.
HIV infection in children must be differentiated first of all with primary immunodeficiencies, as well as with immunodeficient conditions arising in connection with prolonged use of glucocorticoids and chemotherapy.
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