SARS in Canada and China: The World Health Organization (WHO) issued an advisory Apr. 23 recommending that travelers defer all but essential travel to Toronto, Canada, and Beijing and Shanxi Province, China. The WHO assessment “considered the magnitude of the outbreak, including both the number of prevalent cases and the daily number of new cases, the extent of local chains of transmission, and evidence that travelers are becoming infected while in one area and then subsequently exporting the disease elsewhere.” In the case of China it was an extension of advice already in place for Guangdong Province and Hong Kong. The advisory will be reassessed in three weeks, twice the incubation period of the disease. The U.S. Centers for Disease Control and Prevention (CDC) is now handing out notices to all travelers returning to the U.S. from Toronto warning them to be alert for SARS symptoms and, if detected, to seek medical attention immediately.