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

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.

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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.