WUHAN, China — Facing growing pressure to contain a deadly viral outbreak that has spread halfway around the world, China’s ruling Communist Party raced on Tuesday to confront the disease, slapping restrictions on the city where it started and warning that anyone who hides infections will be “forever nailed to history’s pillar of shame.”

The response by the Chinese leadership, which has come under intensifying criticism that it has been slow to acknowledge the severity of the outbreak, came as fatalities from the disease tripled to at least nine. Infections surged from 200 to 440, and global financial markets were rattled by the possibility of a pandemic emanating from the world’s most populous country during the Lunar New Year — Asia’s heaviest travel season.

Already, cases of the pneumonia-like virus have been found in Taiwan, Japan, Thailand and South Korea, and on Tuesday the first was confirmed in the United States. Airports in Atlanta and Chicago said they would screen passengers from Wuhan, joining airports in New York, Los Angeles, San Francisco and cities around the world in doing so. North Korea temporarily closed its borders to foreign tours, the vast majority of them from China. The World Health Organization has called a meeting on Wednesday over whether to declare the outbreak an international health emergency.