Nowadays, microbes are misused as biological weapons. For instance, a single gram of the most virulent strains of weaponized smallpox or anthrax could contain 250 million infectious doses. Under ideal dispersal conditions, about half the people of the entire world when exposed to these germs could become ill and one-third might die.
Even from a very long period, pathogens causing some of the deadliest diseases in men are being used as biological weapons. More than 2,000 years ago, Scythian archers used their arrow heads which were dipped in rotting corpses in order to cause panic amongst people. The tips of arrowhead caused infections. During World war II, papar bags filled with plague infested fleas were employed as biological weapons to kill thousands of people. At that time, well equipped and expensive laboratories were established to mass produce biological weapons. At present, each and every nation is facing the threat from biological weapons. People affected by the biological war have to suffer throughout their life.
Using Molecular biology techniques, new combinations of genes were attempted to create genetically modified organisms (GMO). Some of the most lethal agents known to have been tested in biological warfare are anthrax, plague, smallpox and Ebola viruses with viral diseases.
People were aware of the reality that a small group of fanatical terrorists could easily contaminate the country's air, water and food with lethal pathogens or biological toxins.
Thus biological warfare introduces issues of pathogenicity, toxicity, routes of exposure, safety measures and the movement, distribution and persistence of dangerous biological materials in our environment. In biological warfare strategies, the genetically engineered microorganisms are made to spread into the enemy's territorial environment, with unpredictable and perhaps catastrophic consequences. The released dangerous microorganisms 'upset the balance of nature'.