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Symptomatic HIV infection in infancy--clinical and laboratory markers of infection
Insights
Elevated immunoglobulin G (IgG) levels combined with HIV antibody tests can accurately diagnose HIV infection in symptomatic infants under 15 months. This simple, cost-effective method aids diagnosis in resource-limited settings.
Area of Science:
- Pediatric Infectious Diseases
- Clinical Immunology
- Diagnostic Microbiology
Background:
- Early diagnosis of Human Immunodeficiency Virus (HIV) infection in infants is crucial for timely intervention and improved outcomes.
- Immunological markers offer potential for non-invasive and accessible diagnostic tools.
Purpose of the Study:
- To evaluate the utility of various immunological tests for diagnosing HIV infection in symptomatic infants younger than 15 months.
- To identify reliable immunological markers that can aid in the early detection of pediatric HIV.
Main Methods:
- A cohort of hospitalized infants (<15 months) with symptomatic presentations were assessed.
- Immunological tests including total IgG, IgM, IgA, and rheumatoid factors were evaluated.
- Results were correlated with HIV antibody status and HIV viral product detection via PCR.
Main Results:
- Elevated total IgG levels (≥18 g/L) demonstrated the highest diagnostic utility among the evaluated immunological markers.
- The radial immunodiffusion method for IgG measurement showed excellent reproducibility.
- The combination of elevated IgG and positive HIV antibody test achieved 100% positive predictive value for HIV infection.
Conclusions:
- Elevated total IgG levels, particularly when combined with HIV antibody detection, serve as a valuable diagnostic indicator for HIV infection in symptomatic infants.
- Measurement of total IgG via radial immunodiffusion is a simple, cost-effective, and reproducible method suitable for resource-limited settings.
- While oral thrush was associated with HIV, clinical signs alone were not highly predictive; immunological markers are essential for accurate diagnosis.
Objective:
To investigate the usefulness of immunological tests in the diagnosis of HIV infection in young symptomatic children (< 15 months of age).
Design:
Tests were evaluated in HIV-infected (HIV antibody- and PCR-positive) patients and non-infected individuals.
Setting:
Hospitalised patients in a referral centre (Red Cross War Memorial Children's Hospital, Cape Town).
Patients:
All admissions under 15 months of age who had HIV antibody requested were eligible, provided there was sufficient serum (150 microliter) for further study. Overall, there were 201 symptomatic cases and 49 healthy controls. Twenty of the symptomatic cases were HIV antibody-positive and 19 of these were HIV-infected on the basis of a positive PCR for HIV viral product.
Results:
Of the tests we evaluated (total IgG, IgM, IgA and rheumatoid factors of the same classes), raised total IgG level (cut-off 18 g/I or above) was the most useful. We used a commercial radial immunodiffusion plate which was found to have excellent reproducibility (inter-assay coefficient of variation 3.2%). The test detected 16 of 19 infected infants (sensitivity 84%, negative predictive value 98%). With the exception of the finding of oral thrush (odds ratio 7; P < 0.001), the clinical signs at presentation did not distinguish those who were HIV antibody-positive from those who were negative.
Conclusions:
In our study of hospital admissions, the finding of elevated IgG and HIV antibody was diagnostic of HIV infection. (The positive predictive value of the combination was 100%.) Likewise, the presence of raised IgG levels and oral candidosis had a high specificity for HIV infection (98%) but the sensitivity was low (37%). Measurement of total IgG levels by radial immunodiffusion is simple, relatively inexpensive (< 10% of the cost of PCR), helpful in diagnosing HIV infection in symptomatic infants and able to be performed in areas with minimal laboratory back-up.