Filmmaker: Gerald Sperling
In the summer of 2011, an outbreak of a new, aggressive strain of E.coli killed 45 people in Germany and sickened another 3,800.
Egyptian fenugreek was eventually named the culprit, although how the seeds got infected was never proven.
Some authorities believed it could have been an act of terrorism. And if it was, it echoed a 2008 World Health Organization (WHO) report which claimed the deliberate contamination of food as one of major global threats of the 21st century.
Whether it is the infection of water supplies in Nigeria, milk tanks in Minnesota, fenugreek seeds in Egypt, the world must learn how to deal with this new form of bio-terror, a global threat that cannot be ignored.
By Gerald Sperling
Invisible Threat examines the history of humans developing and using bio weapons - primarily the Japanese, the Americans, the Soviets, the British and the Canadians.
| We examine the history of humans developing and using bio- weapons [Al Jazeera]
It also explores the possible fallout from this massive military endeavour. Although states now have laws now prohibiting the use of these weapons, the Internet allows small groups of people and individual operators access to toxic recipes and the means by which to use them.
And we are already seeing such attacks in countries like the US, and there are still those who believe the E.coli outbreak in Europe in 2010 was intentional.
What is frightening to me is that in its rush to stockpile cures for outbreaks of pathogens, science has created new strains in labs that are subject to human failings - either by accident or intentionally.
I love to travel and, like most people, I sometimes hesitate to place a hand on a much-used railing in a public stairway or have felt the uncomfortable press of people packed into a subway car.
Nature's pathogens can spread so easily, so rapidly. And what is worse is that humans are capable of terrorising and killing using these invisible, ordourless weapons - we only need to look back at our history to substantiate this argument.