Scientists have identified the virus behind the deadly Severe Acute Respiratory Syndrome (SARS) disease as a mutant relative of the cause of the common cold.
The previously unknown coronavirus is believed to have originated in animals before changing and passing on to humans, according to a study published in the
New England Journal of Medicine.
The finding should enable researchers to develop a simple test to detect the disease.
"Preliminary studies suggest that this virus may never before have infected the US population," said Dr Larry Anderson of the American Centre for Disease Control and Prevention, who helped identify the virus. "Certainly, it has not circulated widely in humans. Presumably, this virus originated in animals and mutated or recombined in a fashion that permitted it to infect, cause disease, and pass from person to person."
He said while coronaviruses were best known as the cause of the common cold, they had also caused severe diseases in animals.
Scientists proposed naming the new virus after World Health Organisation medic Dr Carlo Urbani, who died of SARS last month after treating one of the first patients infected with the virus in Vietnam.
SARS has infected more than 2,700 people worldwide, and killed at least 106, according to the WHO. Symptoms include high fever, aches, dry cough and shortness of breath. Some patients must be put on respirators to help their lungs function.
More than 100 viruses are linked with cold symptoms. Coronaviruses are thought to be the second most likely cause of sore throats, coughs, sneezing and congestion after rhinoviruses.
In SARS, the symptoms can be much more serious, possibly leading to a collapse of lung function and, in about 4 per cent of cases, death.
AP