The most frequently posed question is ‘Is my child HIV negative?’
Unfortunately it is difficult to answer this in situations with no
facility for virological assays. The present guidelines
categorically state that rapid HIV antibody testing is not
recommended in HIV-exposed infants less than 18 months of age
because of persisting maternal antibodies. DNA PCR or RNA
qualitative tests are the recommended tests [1-4]. This
recommendation is focused on detecting HIV-infected infants, not the
HIV negative.
In our scenario, DNA PCR is expensive, not freely
available, needs repeated testing and has longer reporting time.
Rapid HIV antibody tests have the potential to detect negative
status and are underutilized due to ignorance in interpretation of
results. Early detection of negative status is useful to assess
effectiveness of PPTCT interventions, limit need for long-term
follow up and allay parental anxiety. National AIDS Control
Organization (NACO) has only recently introduced DNA PCR for infant
testing in a phased manner. They recommend DNA PCR in children <6
months, and rapid test for those >6 months with DNA PCR in this age
group only if rapid test is positive.
We assessed the utility of HIV rapid tests in
HIV-exposed infants less than 18 months of age to detect negative
status.
This was a retrospective, descriptive study,
between January 2006 to August 2010 at St. John’s Medical College
Hospital, Bangalore. We included all HIV-exposed infants less than
18 months, registered in our comprehensive PPTCT program. All
infants underwent rapid HIV antibody test and confirmatory DNA PCR
tests or repeat rapid tests at 18 months to confirm negative status.
In our study, all infants testing positive initially on rapid tests
tested negative on repeat testing at various ages. In all, 78
samples from 63 infants were tested. Each sample underwent two tests
with different kits (Combaids/ Capillus and Tridot) and the results
were categorized as positive result (not the same as HIV positive
status) if 2 tests positive, negative result if 2 tests negative
(same as negative status), and indeterminate if 1 positive and 1
negative test. Testing in breastfed group was repeated 6 weeks after
cessation of breast feeding. Of the total 78 samples, 62 tested
negative, 8 were tested positive and 8 indeterminate. We categorized
the infants into different age bands to assess the percentage
negatives with relation to age (Table I).
TABLE I HIV Rapid Test Results Across Age Bands
Age band |
Positive |
Negative |
Indeterminate |
(mo) |
n(%) |
n (%) |
n (%) |
1-3 |
3 (33) |
4 (45) |
2
(22) |
4-6 |
5 (13) |
27 (71) |
6
(16) |
7-9 |
0 |
9 (100) |
0 |
9-12 |
0 |
8 (100) |
0 |
> 12 |
0 |
14 (100) |
0 |
Total |
8 |
62 |
8 |
Studies reveal very limited durations of
follow-up of HIV-exposed infants, underscoring the need for
confirming HIV status as early as possible [5]. There was rapid
decay of maternally derived antibodies in 31 negative children by 6
months, with 100 % of them testing negative between 7–15 months [6].
In the absence of HIV PCR tests, rapid tests done early in infancy
are useful to detect negative status. In our study, a significant
percentage of infants tested negative by 6 months of age.
Infants can be offered HIV rapid antibody testing
even at <18 months of age to prevent a lost opportunity to detect
negative status. We suggest 3.5 – 6 months as ideal timing during
routine immunization visits. Retesting should be offered 6 weeks
after cessation of breast feeding in all infants to confirm results.
It is a useful supplement to PCR to detect negative status.
Contributors: CD: Concept, planning, data
collection and conduct of the study and guarantor of the study. AS,
CKI and DG: drafting and critical revision.
Funding: None; Competing interests:
None.
References
1. AAP Committee on Pediatric AIDS. HIV testing
and prophylaxis to prevent mother-to-child transmission in the
United States. Pediatrics. 2008;122:1127-34.
2. Kerr RJ, Player G, Fiscus SA, Nelson JA.
Qualitative HIV RNA analysis of DBS for diagnosis of infections in
infants. J Clin Microbiol. 2009;47:220-2.
3. Stevens WS, Noble L, Berrie L, Sarang S, Scott
LE. Ultra-high-throughput, automated nucleic acid detection of HIV
for infant infection diagnosis using the Gen-Probe Aptima HIV-1
screening assay. J Clin Microbiol. 2009;47:2465-9.
4. Walter J, Kuhn L, Semrau K, Decker DW, Sinkala
M, Kankasa C, et al. Detection of low levels of human
immunodeficiency virus (HIV) may be critical for early diagnosis of
pediatric HIV infection by use of dried blood spots. J Clin
Microbiol. 2009;47:2989-91.
5. Chilongozi D, Wang L,Brown L, Taha T,
Valentine M, Emel L, et al. Morbidity and mortality among a
cohort of human immunodeficiency virus type 1-infected and
uninfected pregnant women and their infants from Malawi, Zambia, and
Tanzania. Pediatr Infect Dis J. 2008;27:808-14.
6. Parekh BS, Shaffer N, Coughlin R, Hung CH,
Krasinski K, Abrams E, et al. Dynamics of maternal IgG
antibody decay and HIV-specific antibody synthesis in infants born
to seropositive mothers. The NYC Perinatal HIV Transmission Study
Group. AIDS Res Hum Retroviruses. 1993;9:907-12.