The World Health Organization says it's keeping a close eye on the latest outbreak of severe acute respiratory syndrome in Toronto.

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The group has decided not to issue another travel advisory for the city, despite Monday's report of 52 new probable cases of the respiratory disease. But the possibility has been discussed.

The world health officials say the new SARS cases appear to be confined to a hospital setting. More than 6,800 people remain under home quarantine.

A spokesman said WHO is "concerned" about the size of Toronto's second outbreak and about reports the city may be exporting the disease. There have now been a total of 62 probable cases reported in the city.

The U.S. Centers for Disease Control and Prevention has reinstated a travel alert for Toronto.

China Says SARS Fight 'Far From Over'

The number of new SARS cases in China is falling, but Chinese health officials say the battle with the virus is "far from over."

They're keeping strict measures in place to prevent a flareup. China has imposed travel restrictions, checks airline and train passengers for fever and has closed public schools and entertainment sites in Beijing. Although some Beijing schools have reopened, thousands of people are still in isolation.

The World Health Organization is still worried that Beijing officials don't know how half the people who got sick in the capital caught the disease. They are also concerned about the situation in some of the remote provinces, which lack a strong health infrastructure.

WHO experts are coordinating a series of training courses in Beijing to establish an efficient laboratory infrastructure for SARS diagnosis in all provinces throughout China. Experts are training Chinese scientists to use currently available tests to diagnose the disease

SARS has killed at least 334 people in mainland China and infected more than 5,300. Worldwide, the disease has killed 770 people and infected more than 8,300.

WHO: Diagnostic Tests Progressing Slowly

World health officials say the development of commercial diagnostic tests for SARS has progressed more slowly than they had initially hoped. They said the delay is due to certain unusual features of the virus that make it a scientific challenge.

To help the development of diagnostic tests, the WHO is collecting a bank of clinical specimens from SARS patients.

In the absence of a diagnostic test, the WHO continues to recommend use of its case definitions, based on clinical presentation, distinct chest X-rays, and history of possible contact with SARS patients, to detect suspected and probable cases.

Meanwhile, U.S. health officials are offering a new experimental laboratory test for SARS to about 100 specialized laboratories around the country.

The test, developed rapidly by the Centers for Disease Control and Prevention, is still under investigation. Since information about the test's performance is still being collected, patients will be asked for written consent before it is used.

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