The World Health Organization estimates that more than 450 people in 13 countries worldwide have been infected with Severe Acute Respiratory Syndrome (SARS) in the past two weeks.

So far 17 people are thought to have died from the disease, with another five deaths in the Guangdong province of China, where authorities suspect the outbreak started, closely linked.

Eleven laboratories in nine countries are working to find a cure for the disease. But so far there has been no consistency in their findings.

The mysterious and deadly flu-like illness from Asia that has stymied health officials around the world appears to be caused by a new variety of a common cold virus, U.S. health officials said.

Many different viruses can cause colds, including three different varieties of the coronavirus. Until now, the cold is the only human ailment known to be caused by coronaviruses, but the Centers for Disease Control and Prevention said the culprit in the Asian outbreak appears to be genetically different and probably represents a fourth type.

Symptoms include high fever and one or more of the following respiratory symptoms: cough, shortness of breath or difficulty breathing.