Several bacterial, viral agents and toxins can pose public health risk in the event of a bioterrorist or biological warfare attack These agents, if used in any such attacks, can pose a difficult public health challenge and can cause large number of causalities and will be difficult to contain. The alleged used of biological agents is a serious problem and the risk of using these agents in a bioterrorist attack is increasing. In the ancient history, the well-known attempt of use of biological warfare agent was during the 14th century medieval siege of Kaffa, Feodosiya, Ukraine.In this incident, the Tartars (Mongols) who attacked Kaffa, tossed dead and dying plague victims into the city in an attempt to spread the disease. In another well-documented incident at Fort Pitt, Ohio River Valley, the British troops deliberately spread smallpox among native Indian population by presenting them with blankets and linens used by smallpox victims