Andrew Browne, the WSJ's Beijing bureau chief, has a powerful story just now with names and details of Mexicans being detained and quarantined in China because they are Mexican, not because they've necessarily been in Mexico recently or exposed to flu patients. He has names, details, and quotes about cases like those I mentioned on Saturday:

Gustavo Carrillo, a 36-year-old manager of a Mexican technology company in China who lives in Beijing, was taken off his Continental Airlines plane Saturday and rushed into quarantine at a Beijing hotel. He had traveled to the U.S. from China on a business trip and hadn't visited Mexico.

Mr. Carrillo said health officials took the temperatures of other passengers after the plane landed, but didn't check his after they saw his Mexican passport. Instead, they led him down the aisle past gawking passengers. "It was embarrassing and humiliating," he said.

And:

According to accounts from Mexicans in the hotel, Mexican travelers arriving on various flights from Mexico and the U.S. were singled out by health officials who boarded the aircraft wearing white protective suits, masks and rubber gloves. They led away Mexican passport holders. Several travelers said Chinese television camera crews surprised them at the doors of their aircraft as they emerged. They said the filming continued through the windows of an isolation ward at the Beijing Ditan infectious diseases hospital.

"We felt like we were in a zoo," said Angel Yamil Silum, a 27-year-old business student, who arrived in Beijing with his girlfriend Saturday en route to Bangkok for a holiday, and ended up at Ditan and then the Guo Men Hotel.

Again, China has every reason to be careful about this disease, given the memory of SARS. I've assumed this was a panicky overreaction by local officials, which would be corrected once calmer heads prevailed. The calmer-heads stage does not seem to have started yet.