Smallpox: an old disease but still a threat in the XXI century

Throughout history, smallpox was a severe, highly contagious disease caused by the variola virus. The disease, which existed in a natural form until 1977, had great importance in the history of humanity, but has now been eradicated after a successful worldwide vaccination program. After the last naturally occurring case, in Somalia in 1977, routine vaccination against smallpox among the general public ceased because it was no longer necessary for prevention.The fact that we have returned to the study of smallpox, once eradicated, is that it is one of the main biological agents which can be used as a biological weapon of bioterrorism. The smallpox virus is included in the A category of classification of the US Centers for Disease Control and Prevention, because: it can be easily disseminated or transmitted from person to person; there are high mortality rates; the potential for a major public health impact is high; public panic may be caused; social disruption could follow and special action for public health preparedness would be required. In this chapter, we analyze the characteristics of the virus and the possibility of its use in a bioterrorist attack. We describe the “table-top ” exercises practiced since 2001 and the situation and the future of the cultures of virus stockpiled in the Federal State Research Center of Virology and Biotechnology (Vector) of Russia and the CDC of the United States, under supervision of the WHO. Finally we analyze the WHO resolution, taken in May 2007, to delay for at least four years any decision on when to destroy the world's last known stockpiles of smallpox