HIV diagnostic challenges in breast-fed infants of mothers on antiretroviral therapy

Abstract

Background: Prompt initiation of antiretroviral therapy (ART) for HIV-infected infants is strongly recommended but diagnostic confirmation is important as committing children to life-long ART carries serious health and social implications.

Methods: Two HIV-exposed infants in Johannesburg, South Africa were identified presenting with unusual trajectories of diagnostic nucleic acid amplification tests (NAAT) and viral load results.

Results: Case 1 had repeat indeterminate NAAT results during the first 3 weeks of life; repeat testing thereafter was negative with undetectable viral load including after daily nevirapine prophylaxis ended. ART was not initiated at this time. Case 2 had a single positive NAAT result at 1 month of age that prompted initiation of ART. Subsequent results were negative and ART was discontinued. Repeat negative NAAT with viral load below the limit of quantification or undetectable continued to be obtained. Shortly after and around weaning, positive NAAT results with high viral load (7.1 and 6.03 log10 copies/ml for Cases 1 and 2, respectively) were observed in both children. Both mothers were treated with tenofovir, emtricitabine and efavirenz during breastfeeding. Testing with ultrasensitive assays on early samples conclusively revealed HIV-1 proviral DNA in Case 1. Testing with ultrasensitive assays after the early period but prior to weaning did not detect HIV in either infant.

Conclusion: We hypothesize that breast milk from the mothers of these two rare cases had HIV-specific or nonspecific factors that led to the undetectable results in already infected infants until breastfeeding ended. Our results raise the importance of repeat testing of HIV-exposed breast-fed infants after complete cessation of all breastfeeding.

Figure 1:

Summary of infant and maternal tests and antiretroviral drug exposures in Case 1 and Case 2. Abbreviations: ddNVP – daily nevirapine prophylaxis; VL – Viral load; ART – Antiretroviral therapy; LPVR – lopinavir/ritonavir; 3TC – lamivudine; ABC – abacavir; PCR diagnosis N – negative, I – indeterminate, P – positive; EFV – efavirenz; FTC –emtricitabine; TDF – tenofovir; EBF – Exclusive breastfeeding; Non-EBF – breastfeeding continues but is not exclusive.

Figure 2.

A: Diagnostic HIV-1 PCR test results, viral load tests and samples tested using integrase-based nested PCR at different time points. B: Using the number of replicates that tested positive (as a percentage) divided by the average of the Ct values obtained from the positive replicates, a value representing the relative proviral burden of HIV-1 cell-associated DNA was calculated and plotted on a bar graph for the different time points tested for both cases. C: Quantitation of total cell-associated HIV-1 DNA plotted on a bar graph for the time points tested for both cases.