On April 22, the United States Centers for Disease Control and Prevention (CDC) issued a travel alert, concerning Toronto.

Canadian officials were dismayed by today's WHO announcement, which came as an obvious shock. The economic implications for Toronto (as for other areas with SARS outbreaks and community spread) have been serious. This will worsen with the WHO announcement.

"The reason that the recommendation was put in place was because of the exportation of cases, transmission outside the hospital setting and ... the large number of cases," Dick Thompson told The Canadian Press in a telephone interview from Geneva." says the CP release.

In another interview with Canadian Press, David Heymann, WHO's Chief of infectious disease, provided a partial explanation, but deepened the mystery. "Toronto last week had an exportation (of the disease) which set up a cluster of five cases in health workers in another country... This is what called it again to our attention."

There were only three SARS exportations from Canada in the past few weeks, according to a review of news items. One was a man from Toronto's BLD Covenant (Filipino-Catholic religious sect) cluster of SARS cases. He travelled to Philadelphia, USA, where he was diagnosed with SARS.

The second case of a Canadian, who took SARS to another country, was a nurse who left Toronto and died April 6, of probable SARS pneumonia, in the Philippines. The nurse, Adela Catalon, apparently had contact with 600 wedding guests, 250 relatives and others. Her father died April 22, with a fever that was initially attributed to colon cancer, not SARS.

The Philippines say they have only one SARS case, other than Ms. Catalon.

Today, Toronto public health officials revealed a third case of possible SARS exportation -- an individual who travelled to the US -- the Toronto authorities sent an aircraft to retrieve that person from the US.

The mystery is this: Which country had the cluster of 5 SARS cases, in health care workers, after a SARS case travelled from Canada?

Multiple WHO experts and spokespeople have been interviewed by the Canadian media. All these WHO personnel refuse to name that country. Several said that they did not have the permission of that country.

A plausible explanation is that the cluster of 5 cases, amongst health care workers, is in a country that is not allowing WHO to reveal the true extent of SARS, in that country.

If you have clues, please post them to the 4/23 SARS Update thread, on the bulletin board.