Chapter 8 explains how blood-borne viruses are transmitted through contaminated injections. Throughout the world, intravenous drug users are a high-risk population for HIV and the hepatitis C virus. Medical interventions that re-used unsterilised syringes and needles were also implicated in the transmission of blood-borne viruses. In Egypt, millions were infected with the hepatitis C virus through the mass treatment of schistosomiasis, a parasitic disease. Hundreds of thousands of American soldiers were infected with the hepatitis B virus during World War II through a contaminated yellow fever vaccine. In Romania, Libya, the former Soviet Union, and more recently in Cambodia and Pakistan, large outbreaks of iatrogenic HIV infection have been reported and continue to occur.