The sharing of needles is a common route of transmission in developing countries because of insufficient supplies of sterile equipment for medical use. In poor countries, including Russia and some nations in Eastern Europe, medical personnel often use one syringe repeatedly for giving immunizations or injections of therapeutic drugs. If one of the patients is HIV positive, this practice may transmit the infection to everyone who later receives an injection with the same needle.
According to the World Health Organization, 40 percent of injections worldwide are given with unsterile needles. Transfusion with HIV-contaminated blood is no longer a significant source of HIV infection in the United States, but it still occurs in countries too poor to screen donated blood. Most of them had lived there during the years of the BSE outbreak among cattle.
Four cases have been reported in the United States, two of whom probably contracted the disease in the United Kingdom and one who probably contracted it in Saudi Arabia. The fourth case, confirmed after a patient died in Texas in 2014, occurred in a man who had traveled widely in Europe and the Middle East. Regulations on cattle feed have been tightened, and certain ruminant parts are prohibited from entering the food supply.