Biological agents are organisms or toxins that can kill or incapacitate people, livestock, and crops. A biological attack is the deliberate release of germs or other biological substances that can make you sick.
There are three basic groups of biological agents that could likely be used as weapons: bacteria, viruses, and toxins. Biological agents can be dispersed by spraying them into the air, person-to-person contact, infecting animals that carry the disease to humans, and by contaminating food and water.
A biological attack may or may not be immediately obvious. In most cases local health care workers will report a pattern of unusual illness or there will be a wave of sick people seeking emergency medical attention. The public would be alerted through an emergency radio or TV broadcast, or some other signal used in your community, such as a telephone call or a home visit from an emergency response worker.