Bioterrorism is the intentional release of of biological agents. It can be used in warfare. According to the U.S. Centers for Disease Control and Prevention bioterrorism is the deliberate release of viruses, bacteria, toxins or other harmful agents to cause illness or death in people, animals, or plants. Biological agents spread through the air, water, or in food. Some can also spread from person to person. They can be very hard to detect. They don’t cause illness for several hours or days. Biodefense uses medical measures to protect people against bioterrorism. This includes medicines and vaccinations. It also includes medical research and preparations to defend against bioterrorist attacks.