That would be a war crime.

Quote:

During the past century, more than 500 million people died of infectious diseases. Several tens of thousands of these deaths were due to the deliberate release of pathogens or toxins, mostly by the Japanese during their attacks on China during the Second World War. Two international treaties outlawed biological weapons in 1925 and 1972, but they have largely failed to stop countries from conducting offensive weapons research and large-scale production of biological weapons. The history of biological warfare http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1326439/

ISIS does not want to get behind in biological warfare development. If we are lucky they will have an 'accident' and wipe themselves out otherwise we will have problems with biological attacks in public places.