There are now 20,000 people at 400 sites around the US working with putative bioweapons germs, says Ed Hammond of the Sunshine Project, 10 times more than before the terrorist attacks of 9/11.

Some scientists have warned for years that more people handling dangerous germs are a recipe for accidents.

The fears have been borne out by publicised infections of lab workers with tularemia, brucellosis and Q fever.