GMO advances give are opportunities to construct pathogens with high lethality (Ebola like) with spreading like Flu.

High

Convention on the Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on Their Destruction
http://www.un.org/ga/search/view_doc.asp?symbol=BWC/CONF.VII/7

https://en.wikipedia.org/wiki/Biological_warfare

https://www.un.org/disarmament/wmd/bio/