Blood-Borne Pathogens: Infectious organisms in the BLOOD, of which the predominant medical interest is their contamination of blood-soiled linens, towels, gowns, BANDAGES, other items from individuals in risk categories, NEEDLES and other sharp objects, MEDICAL WASTE and DENTAL WASTE, all of which health workers are exposed to. This concept is differentiated from the clinical conditions of BACTEREMIA; VIREMIA; and FUNGEMIA where the organism is present in the blood of a patient as the result of a natural infectious process.Needlestick Injuries: Penetrating stab wounds caused by needles. They are of special concern to health care workers since such injuries put them at risk for developing infectious disease.Universal Precautions: Prudent standard preventive measures to be taken by professional and other health personnel in contact with persons afflicted with a communicable disease, to avoid contracting the disease by contagion or infection. Precautions are especially applicable in the diagnosis and care of AIDS patients.Infectious Disease Transmission, Patient-to-Professional: The transmission of infectious disease or pathogens from patients to health professionals or health care workers. It includes transmission via direct or indirect exposure to bacterial, fungal, parasitic, or viral agents.