In the final months of 2001, five people died because they opened their mail. The killers were hidden inside the envelopes, small spores that were inhaled by the unfortunate addresses. Inside their bodies, the spores turned into the deadly bacteria, Bacillus anthracis – anthrax.

Anthrax has a long history in biological warfare but it made its debut as an agent of bioterror in 2001. The US anthrax postal attacks infected 22 people and claimed the lives of five. Since then, scientists have been feverishly studying the bacteria responsible in the hope that better understanding will lead to effective treatments. Two years ago, one group managed to develop a potential new treatment that neutralises anthrax toxins by acting on the host’s own