Pathogenesis describes the mechanisms involved in the production of a disease. This includes the spread of microorganisms and anthropogenic and natural toxins through the body and the physiological responses of the host organism. Many pathogenic agents that cause infectious diseases are considered as ideal selective agents by terrorist groups, which include anthrax, ebola, pneumonic plaque, cholera, tularemia, brucellosis, Q fever, Venezuelan equine encephalitis, smallpox, swine and avian influenza. Biotoxins are naturally occurring toxic agents produced by bioorganisms such as bacteria, cyanobacteria, fungi, and some species of plants and marine fish, which are etiological agents of a variety of animal and human toxicoses. Several biotoxins, such as aflatoxin, botulinum toxin, ricin, and T-2 toxin, have been known to be weaponized. Various levels of training on potential pathologic and toxic agents are needed to ensure that individuals and communities get involved in countermeasure activities and have a good understanding of the potential threats and their role, as well as its consequences.