A blood-borne disease is a disease that can be spread through contamination by blood and other body fluids. Blood can contain pathogens of various types, chief among which are microorganisms, like bacteria and parasites, and non-living infectious agents such as viruses. Three blood-borne pathogens in particular, all viruses, are cited as of primary concern to health workers by the CDC-NIOSH: HIV, hepatitis B (HVB), & hepatitis C (HVC). Diseases that are not usually transmitted directly by blood contact, but rather by insect or other vector, are more usefully classified as vector-borne disease, even though the causative agent can be found in blood. Vector-borne diseases include West Nile virus, zika fever and malaria. Many blood-borne diseases can also be contracted by other means, including high-risk sexual behavior or intravenous drug use. These diseases have also been identified in sports medicine. Since it is difficult to determine what pathogens any given sample of blood contains, and some blood-borne diseases are lethal, standard medical practice regards all blood (and any body fluid) as potentially infectious. "Blood and body fluid precautions" are a type of infection control practice that seeks to minimize this sort of disease transmission. Occupational exposure Blood poses the greatest threat to health in a laboratory or clinical setting due to needlestick injuries (e.g., lack of proper needle disposal techniques and/or safety syringes). These risks are greatest among healthcare workers, including: nurses, surgeons, laboratory assistants, doctors, phlebotomists, and laboratory technicians. These roles often require the use of syringes for blood draws or to administer medications. The Occupational Safety and Health Administration (OSHA) prescribes 5 rules that are required for a healthcare facility to follow in order to reduce the risk of employee exposure to blood-borne pathogens. They are: Written exposure control plan Engineering controls (Sharps containers, detachable and retractable needles, syringe caps, etc.) Safe work practices and safety devices Hepatitis B vaccine available to employees Education and post-exposure follow up These controls, while general, serve to greatly reduce the incidence of blood-borne disease transmission in occupational settings of healthcare workers. There are 26 different viruses that have been shown to present in healthcare workers as a result of occupational exposure. The most common blood-borne diseases are hepatitis B (HBV), hepatitis C (HCV), and human immunodeficiency virus (HIV). Exposure is possible through blood of an infected patient splashing onto mucous membranes; however, the greatest exposure risk was shown to occur during percutaneous