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Diagnosis of HIV infection / AIDS
Medical expert of the article
Last reviewed: 04.07.2025
Laboratory diagnostics in children with perinatal exposure to HIV infection
Most children born to HIV-infected mothers have HIV antibodies (maternal) in their blood. In this regard, serological methods of diagnosing HIV infection based on the determination of IgG antibodies (ELISA) are not diagnostically significant until 18 months of life, when maternal antibodies are completely destroyed.
Own specific antibodies appear in a child in 90-95% of cases within 3 months after infection, in 5-9% - after 6 months and in 0.5% - later. In children over 18 months, detection of serological markers is considered diagnostic.
Routine serological examinations are performed at birth, 6; 12 and 18 months of life. Obtaining two or more negative results at least 1 month apart in a child without hypogammaglobulinemia aged 12 months or older indicates against HIV infection.
In children 18 months and older, in the absence of HIV infection and hypogammaglobulinemia, a negative result of a serological test for HIV antibodies allows HIV infection to be excluded.
Molecular biological research methods allow for the reliable confirmation of HIV infection in the majority of infected newborns by the age of 1 month and in almost all infected children by the age of 6 months.
The preferred method for diagnosing HIV infection in young children is the detection of HIV DNA by PCR. Among perinatally infected children, 38% have a positive PCR result during the first 48 hours of life, and 93% of children at the age of 14 days. Chemoprophylaxis does not reduce the sensitivity of virological tests.
The first mandatory test is carried out at the age of 1-2 months, the second - after 1 month. If a repeated positive result is obtained, it is necessary to determine the viral load (i.e. the number of copies of HIV RNA in 1 ml of plasma) using a quantitative method, which allows assessing the risk of disease progression and the adequacy of antiretroviral therapy.
Children with negative test results at birth and at 1-2 months of age should be re-examined at 4-6 months of age.
One of the additional methods of examining an HIV-infected child is an assessment of the immune status, namely, determining the percentage and absolute number of CD4+ T-lymphocytes.
After receiving a positive HIV nucleic acid result in a child, it is necessary to conduct a quantitative study of CD4+ and CD8 lymphocytes, preferably by flow cytometry. The study should be carried out regularly every 3 months (2-3 immune category) or 6 months (1st immune category).
If a change in the immunological profile is detected (CD4+ cells <1900/mm3 and CD8- cells >850/mm3 ) in a child in the first 6 months of life, a rapidly progressing form of the disease is assumed.
Differential diagnostics
HIV infection in children must be differentiated primarily from primary immunodeficiencies, as well as from immunodeficiency states that arise in connection with the long-term use of glucocorticoids and chemotherapy.
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