Smallpox is a severe viral infection caused by the variola virus. The virus creates pockmarks all over your body that can become infected. The Smallpox infection was eliminated from the world in the late 1970s. However, because the security of the virus is uncertain, there is a remote risk that smallpox could be used as a weapon. Routine vaccination against smallpox in the United States ended in 1972, because the risk associated with the vaccine was greater than the risk of getting the disease. However, in 2003, some members of the military, public health and healthcare workforce were vaccinated against smallpox as part of bioterrorism preparedness.
Viral hemorrhagic fevers (VHFs) are diseases caused by groups of viruses such as the Ebola virus and Marburg virus. In general, infection with these viruses may cause serious illness with fever and damage to blood vessels affecting many organ systems. Damage to the blood vessels can disrupt blood flow and cause severe bleeding. Although some VHFs are mild illnesses, many can be fatal. Other VHFs include Lassa fever, yellow fever, Crimean-Congo and New World hemorrhagic fever viruses. 
Tularemia is an infection caused by the bacteria Francisella tularensis that can affect animals and humans. It resembles the flu but is much more painful. About 200 cases of human tularemia are reported each year in the United States. Bites from infected ticks and the handling of infected rabbits are responsible for most tularemia cases in the United States. If tularemia were to be released intentionally, as in a bioterror event, the bacteria would most likely be released into the air to be breathed in. 
In elementary school one learns about the Dark Ages; trash was thrown into the streets, showers and bathrooms were non-existent and rats almost took over the towns. Because of all of the filth the Plague ran rampant through villages. Now-a-days the Plague is an uncommon infectious disease of animals and humans; it is caused by Yersinia pestis (Y. pestis) bacteria. Y. pestis is present in wild rodents and their fleas in many areas around the world, including most of the western United States. 
Anthrax is a bacterial disease that is spread through materials containing the anthrax spore. Anthrax spores can survive in the environment for long periods of time, but they seldom affect humans; cattle, sheep and goats are commonly infected. When humans do become infected, it is through handling animals or other materials containing anthrax spores, eating infected meat or breathing in spores. Anthrax cannot be spread from person to person. 
