Knowledge of risk factors for HIV transmission in high-risk population plays a critical role in averting the risk of HIV transmission. In Pakistan, injection drug users (IDUs) constitute the core risk group of HIV prevalence, where the epidemic has transitioned to a "concentrated level." Still nothing is known about the role of knowledge in HIV transmission and HIV sero-conversion among IDUs in Pakistan.

From 2009 to 2011, a nested case–control study was conducted in a cohort of 636 IDUs receiving harm reduction services in the mega city of Karachi.

In multivariable regression analysis, 3 factors, namely HIV does not spread through unprotected sex (adjusted odds ratio [AOR]: 3.1, 95% confidence interval [CI] 1.39-6.90, P value .01), HIV does not transmit by sharing syringes (AOR: 3.5, 95% CI 1.97-6.40, P value <.00), and the risk of HIV cannot be minimized by using new syringe every time (AOR: 2.0, 95% CI 1.16-3.60, P value .01), were significantly associated with the incident cases of HIV.

The study findings suggest the association between knowledge of HIV transmission and HIV sero-incident cases.