The ease and insecure conditions under which they were distributed - along with the growing possibility that a mutated version of avian flu could spread from human to human, and be engineered to do so - add to growing concerns about opportunities for bioterrorism and how ready governments are.
The strain of Asian flu sent to laboratories killed one million people in 1957. On April 12 the World Health Organization ordered the recipients to destroy the sample, but this was shutting the stable door long after the horse had bolted.
While viruses are routinely distributed for researchers to test their ability to identify samples, they normally contain strains in current or recent circulation. It was first believed the samples were a non-lethal strain, but a laboratory in Winnipeg, Manitoba identified them as from the 1957 pandemic and notified the US Centers for Disease Control.
