World health experts are trying to identify the origin of an outbreak of deadly pneumonia, named Severe Acute Respiratory Syndrome (SARS), that appears resistant to standard treatments.

The global death toll from the mystery illness, which is believed to have originated in southern China, is increasing daily as thousands of people around the world are suspected of being infected.

Standard antiviral drugs and antibiotics do not appear to be effective although many patients have shown favorable response to a cocktail of drugs including the antiviral drug ribavirin and steroids.