Application of human immunodeficiency virus type 1 BED enzyme immunoassay on dried blood spots in India

Dried blood spots (DBSs) on filter paper are being used increasingly in population-based human immunodeficiency virus (HIV) studies. This study evaluated the application of a BED enzyme immunoassay (EIA) on DBSs to estimate HIV incidence in a population-based study in India. The Calypte HIV-1 BED Incidence EIA was performed on 224 HIV-1-positive DBS samples, after screening 12 617 individuals from a population-based sample in Guntur district in the southern Indian state of Andhra Pradesh. The number of recently infected HIV cases was identified using this BED assay and was used to estimate the annual HIV incidence rate based on calculations and adjustment formulae suggested by the Centers for Disease Control and Prevention (CDC). The updated BED data management software provided by the CDC was used for analyses. Of the 224 HIV-1 antibody-positive DBS samples, 29 (12.95 %) were estimated by the BED HIV-1 assay to have been infected within the past 155 days. After adjusting for age, gender and rural/urban distribution of the population, the annual incidence rate of HIV-1 infection was estimated to be 0.32 % (95 % confidence interval 0.20-0.44 %). This annual incidence was 18.6 % of the HIV prevalence of 1.72 % in this study. Thus, the BED assay revealed a higher incidence of HIV in this study than was expected from the prevalence. Correlation of the BED assay with panel testing and longitudinal incidence data in the Indian population is needed to calibrate it for use in India.