Viruses are smaller than bacteria and live inside an individual host cell. Rickettesia are small cellular organisms that are smaller than bacteria but larger than a virus. They also live inside an individual host cell. Toxins are substances produced by living organisms including bacteria, plants and animals. They differ from chemical agents, in that most are not manmade.
Biological toxins are some of the most toxic substances known.
Aerosol dispersion is getting it into the air. A garden sprayer, a paint spray gun, or crop dusting devices can be used. All of which are very easy to obtain at any hardware or agricultural store. Ingestion can be through contamination of food, water or even medicine. The agent can be sprinkled on food or mixed in food.