NEW YORK - The swine flu outbreak is unleashing a side effect the global economy is in no condition to handle: fear.

Travelers are canceling or delaying trips to Mexico, Cuba banned all flights to its neighbor and Argentina announced Tuesday a five-day ban on flights arriving from Mexico. China, Russia and South Korea have banned imports of some North American pork, despite assurances that the flu is not spread through meat. Investors just starting to regain their nerve have again caught the jitters.

The threat of a pandemic comes just as the world economy is showing the barest glimmerings of what analysts say might be the light at the end of what remains a long, dark tunnel. And now this.

"This is just another negative shock when the economy can least afford another negative shock," said Jay Bryson, global economist at Wachovia Corp.

So far, fear of the flu is at least as responsible for the economic disruption as the disease itself.

The number of confirmed cases in the United States climbed to 66, and federal officials warned that deaths were likely. In New York, the city's health commissioner said "many hundreds" of schoolchildren were ill at a school where some students had confirmed cases.

President Barack Obama asked Congress for $1.5 billion in emergency funds to fight the disease.

Economists remember well the financial damage the SARS outbreak inflicted in 2003. An epidemic of that scale or greater could inflict severe damage on a global economy already badly listing.

"On top of a synchronized global financial and economic crisis, an outbreak of swine fever is the last thing we need just now," Neil MacKinnon, chief economist at The ECU Group PLC, based in London, wrote this week.

There are already early signs that swine flu fear is taking an economic toll.

In Mexico City, canceled events and closed movie theaters, night clubs, museums and other establishments are costing at least $57 million a day, according to city's Chamber of Trade, Services and Tourism.

That's a 36 percent drop in revenue generated by tourism and services in the Mexican capital, chamber president Arturo Mendicuti said.

Royal Caribbean Cruises suspended stops at Mexican ports indefinitely, and Carnival Cruise Lines canceled Mexico port calls through May 4. Norwegian Cruise Line canceled the Norwegian Pearl's final two calls in Mexico this week and said its schedules do not include any other ports in Mexico until the end of September 2009.

In Chicago, traders bid down the price of pork futures Tuesday for a second straight day, reflecting what analysts say are consumer worries about catching the virus from meat.