Thursday, April 14 2005 08:46 Hrs (IST) - World Time -

Geneva: The World Health Organisation (WHO) issued a warning yesterday (Apr 13, 2005) after a US institute sent to thousands of laboratories samples of a lethal flu virus that slew up to four million people in the late 1950s.

The controversy revealed an apparent loophole in biosafety procedures, experts said.

"There is a slim but a real risk that this could spark a pandemic," said Maria Cheng, a spokeswoman for the WHO, explaining that many people around the world would have no protection if the virus were ever released from the high-security labs.

The virus, H2N2, killed between one million and four million people worldwide during the Asian influenza pandemic of 1957-58 before disappearing in 1968.

"As far as pandemics go, it (the event in 1957-58) was relatively mild. But if this were to recur it would have significant consequences for the public health system," Cheng told agencies.

The samples were included in kits used to regularly test the ability of the laboratories in 18 countries to identify strains of flu virus.

Ninety per cent of the laboratories were in North America.

The virus was sent to laboratories in Belgium, Bermuda, Brazil, Canada, Chile, France, Germany, Hong Kong, Israel, Italy, Japan, Lebanon, Mexico, Saudi Arabia, Singapore, South Korea, Taiwan and the United States, the UN's health agency said.

So far, laboratories in Canada, Hong Kong, Singapore and South Korea were known to have destroyed all the H2N2 samples they received, it said.

The agency's top flu expert, Klaus Stohr, said that all the samples were expected to be destroyed by Friday (Apr 15, 2005).

A US-based private institution, the College of American Pathologists, distributed the samples of H2N2 to 3,747 laboratories through the private Meridian Bioscience Inc in two batches, in October 2004 and February 2005.

The samples appeared to have been distributed deliberately and legally because of national differences in the hazard rating of the strain, Stohr told journalists.

"Legally that's fine, epidemiologically and looking at the risk assessment, it may have not been a good idea to do that," Stohr said.

"It is certainly something that will have to be reconsidered in the future, definitely, and WHO will make recommendations," to ensure that the virus strain is given a higher hazard rating, he added.

The WHO said normally only circulating influenza virus strains to which people have been exposed in recent years should be sent out in testing kits.

It warned in a statement on Tuesday (Apr 12, 2005) that people born after 1968 would probably have no or only limited immunity to the strain, which is not contained in current influenza vaccines.

The alarm was first raised by Canada's National Microbiology Laboratory after it detected H2N2 virus in a sample on March 25, leading to an alert issued by US authorities through the College of American Pathologists on April 8.

So far, there have been no reports of accidental infection among laboratory workers, the WHO said.