Is there really any chance of genetically engineered flu viruses escaping from the laboratory? History suggests there is no room for complacency.
Perhaps the most serious incident concerns the H1N1 flu strain, to which the 1918 virus belonged. It disappeared after the Asian flu pandemic in 1957. But in 1977, H1 suddenly reappeared, causing a mild epidemic. The strain was identical to one isolated in 1950.
It is extremely unlikely that the virus could have circulated unaltered for 27 years. This has led some scientists to think it re-emerged from a laboratory freezer. A lab worker might have become infected. Another theory is that an incompletely inactivated batch of vaccine was to blame. H1 remains in circulation today.
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A meeting in Asilomar, California, in 1975 established the principle that the level of containment should match an organism鈥檚 presumed risk. But this took time to implement. In 1979 at the University of Birmingham, UK, some smallpox virus floated from a faulty safety cabinet to the floor above, killing a woman. Only strict quarantine prevented a wider outbreak.
World Health Organization guidelines now specify four 鈥渂iosafety levels鈥�: BSL-1 for harmless microbes; BSL-2 for non-contagious, curable diseases like anthrax; BSL-3 for serious but curable and not very contagious pathogens; and BSL-4 for incurable, contagious nightmares like Ebola.
But mistakes still happen. The Council for Responsible Genetics pressure group lists 17 recent accidents and security breaches at biosafety labs in the US. Incidents include packages breaking open, missing samples and power failures causing a loss of containment.
Just last week, a lab worker at the US Army Medical Research Institute of Infectious Diseases at Fort Detrick, Maryland, grazed herself with an Ebola-infected needle. Last year two scientists developed the respiratory disease SARS after separate incidents in BSL-3 labs in Singapore and Taiwan.
鈥淔ortunately, SARS is poorly communicable,鈥� says microbiologist Mark Wheelis of the University of California, Davis. 鈥淏ut what if it had been a flu strain with pandemic potential?鈥� The danger with a disease like flu is that it becomes infectious before any symptoms appear. That means any failure of containment might not be spotted until it is too late.
But D. A. Henderson of Johns Hopkins University in Baltimore, Maryland, who led the drive to eradicate smallpox, thinks the benefits of such research outweigh the risks. 鈥淲e are really short on BSL-4 labs at the moment. We are not doing things we鈥檇 like to.鈥�
The US is already building three new BSL-4 labs. Richard Ebright, a microbiologist at Rutgers University in New Jersey, claims little vital research needs BSL-4, while more labs and more workers means more potential leaks of germs, and more potential terrorist targets.