WHO NEWS

SARS virus identified

On 16 April WHO announced that a new pathogen, a member of the coronavirus family never seen before in humans, is the cause of severe acute respiratory syndrome (SARS). The speed with which the virus was identified is the result of close collaboration between 13 laboratories in 10 countries. Much of the evidence in recent weeks had pointed to strong associations between this virus and the disease, but there had been no conclusive confirmation.

"The pace of SARS research has been astounding," said David Heymann, Executive Director of WHO's Communicable Diseases programmes. "Because of an extraordinary collaboration among laboratories from countries around the world, we now know with certainty what causes SARS."

The collaboration of leading laboratories was established after WHO issued a global alert on SARS on 12 March 2003. Two laboratories in China recently joined the network, consisting of laboratories in Canada, France, Germany, Hong Kong Special Administrative Region of China, Japan, the Netherlands, Singapore, the UK and the USA.

The objective of the 13 laboratories was to meet Koch's four postulates for proving the identity of a disease's causal agent: it must be found in all causes of the disease; it must be isolated from the host and grown in pure culture; it must reproduce the original disease when introduced into a susceptible host; and it must be found in the experimental host so infected. Heinrich Koch, the German bacteriologist, set out these postulates in 1882, the year he isolated the bacillus that causes tuberculosis.

WHO and the network of laboratories dedicate their detection and characterization of the SARS virus to Carlo Urbani, the WHO scientist who first alerted the world to the existence of the disease (see "Frontline health worker" above).

Daily updates on the SARS outbreak are available at www.who.int.