AIDS blood sampling. Gloved hand of a healthcare worker using a vacutainer to take a blood sample from an AIDS patient. A vacutainer is a tube at low pressure that automatically draws blood into itself when a vein is punctured. AIDS (acquired immune deficiency syndrome) is a contagious disease caused by the human immunodeficiency virus (HIV). It can be spread through contact with contaminated blood, so precautions such as wearing sterile protective clothing must be taken when dealing with AIDS patients. This photograph was taken in Africa, where a lack of access to drugs and information makes AIDS a major public health concern.