Trial Information

Validation of Self-Reported Needle Sharing Among Injection Drug Users

Needle sharing is a major cause of blood-borne diseases making understanding needle sharing
behavior imperative to devising strategies to reduce the disease burden. A DNA-based
method, using highly informative genetic markers of short tandem repeats (STRs) is being
proposed as a gold standard measure to identify single-use and multi-use syringes.
Self-reports of needle sharing, which have been the main source of sharing information for
research, will be compared to the genotypic results to validate the responses on such risk
behavior. Genotypic information from four autosomal STRs will be used to differentiate DNA
from a single versus multiple individuals in syringe exudates obtained from injection drug
users (IDUs) from the Baltimore needle exchange program (BNEP) studied by ALIVE II.
Detecting three or more distinct alleles at an autosomal STR in the syringe exudates
provides evidence that the syringe has been shared by at least two individuals. Matching
probabilities will be used to match the genotypic profile of the individual(s) checking in
and returning the syringe to allele(s) observed in the syringe exudates, and a mixture
discrimination probability will be used to measure the likelihood of single vs. multi genome
in the syringe samples. Behavioral surveillance to document the rapid spread of infectious
disease from needle sharing among high-risk sub-population such as IDUs are critical for
global public health along with the development and implementation of timely interventions.