Biological warfare and bioterrorism involve using biological agents like bacteria, viruses and toxins to harm humans, animals or plants. Throughout history, various groups have attempted biological attacks by poisoning wells or using infected bodies. Modern bioweapons development accelerated during World War I and II by nations including Germany, Japan and the US. Biological agents can be cheap and difficult to detect but controlling their spread once used is challenging. The 1975 Biological Weapons Convention banned development and stockpiling of bioweapons but threats still exist from rogue groups. Ongoing challenges include rapid detection, public education and international cooperation to prevent bioterrorism.