title: Symptomatic HIV infection in infancy--clinical and laboratory markers of infection.
abstract: OBJECTIVE
  To investigate the usefulness of immunological tests in the diagnosis of HIV infection in young symptomatic children (< 15 months of age).
  
  
  METHODS
  Tests were evaluated in HIV-infected (HIV antibody- and PCR-positive) patients and non-infected individuals.
  
  
  METHODS
  Hospitalised patients in a referral centre (Red Cross War Memorial Children's Hospital, Cape Town).
  
  
  METHODS
  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.
authors.affiliation: Department of Paediatrics, Groote Schuur Hospital, Cape Town.
authors.forename: M P
authors.initials: MP
authors.lastname: Meyer
authors.forename: Z
authors.initials: Z
authors.lastname: Latief
authors.forename: C
authors.initials: C
authors.lastname: Haworth
authors.forename: S
authors.initials: S
authors.lastname: Salie
authors.forename: A
authors.initials: A
authors.lastname: van Dyk
mesh_terms: D015415:Biomarkers / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D015483:HIV Antibodies / Q000097:blood; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis*; D006679:HIV Seropositivity / Q000097:blood / Q000175:diagnosis; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D012217:Rheumatoid Factor / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D015483:HIV Antibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012217:Rheumatoid Factor