Early diagnosis of human immunodeficiency virus infection status in vertically exposed infants in a low resource setting.

Abstract

Sub-Saharan Africa is the eye of the HIV epidemic. This study was conducted when treatment for the majority of HIV-infected patients in low resource settings was considered unattainable and the risks of diagnosing HIV often outweighed the benefits. Coupled with the complexities of HIV diagnosis in infancy, children typically were only diagnosed once already ill or not at all. Key strategies to address the paediatric epidemic focused on preventing mother to child transmission and reducing mortality and morbidity of infected children predominantly with co-trimoxazole prophylaxis. Both strategies required early diagnosis of HIV infection in infancy for monitoring prevention programs and identifying infected children respectively. The diagnostic algorithm for resource limited settings recommended the use of inexpensive, technically simpler HIV antibody detection assays that are unsuitable for use in HIV-exposed children under 12-months of age. Paradoxically this algorithm provided a barrier to HIV diagnosis in children because of high loss to follow-up rates and death in the first year of life. The objective of this study was to establish an accurate, affordable diagnostic algorithm for early diagnosis of HIV infection that could be rapidly implemented in South Africa and benefit other resource limited settings. The HIV infection status of 300 vertically exposed infants was determined according to first world criteria in a prospective, cohort study at Coronation Hospital, Johannesburg over 21 months. This status was used to assess the accuracy of clinical examinations and HIV assays in diagnosing HIV at 6-weeks, 3-, 7- and 12-months of age. The average cost of determining an infant’s HIV infection status was measured. A single HIV DNA PCR test at 6-weeks of age proved highly accurate in determining HIV status at a marginally increased cost to government and was incorporated by the South African Department of Health into national policy. The ultrasensitive p24 antigen assay and HIV antibody detection assays on serum and oral fluid were identified as valuable candidates where PCR testing is unavailable. Dried blood spot samples from heelpricks are critical for policy to be translated into practice since skills to perform venesection in 6-week old babies are limited. The next challenge lies in operationalising these findings at a clinical and laboratory level to the benefit of the 300 000 South African children annually exposed to HIV at birth. The urgency of early diagnosis has been increased by the availability of highly effective antiretroviral therapy.