U.S. officials are preparing a travel advisory warning Americans against non-essential travel to Mexico, according to the Associated Press. The advisory is being issued "out of an abundance of caution," according to the CDC. Airlines are reporting that some travelers have already switched their plans for vacations in Mexico, but the changes have been "minimal," an American Airlines spokesperson told the AP. Some countries overseas have already issued warnings against travel parts of North America. Meanwhile, cruise operators like Carnival Cruise Lines say scheduled stops in Mexico are going forward over the next few days.

Air traffic from Mexico to BWI-Marshall Airport is fairly limited. There are no nonstop flights between Mexico City and Baltimore, according to a BWI spokesman. AirTran has one daily flight between Cancun and BWI and the airline is waiving change fees for travelers. USA3000 has thrice-weekly service from Mexico City and Cancun and will also waive change fees. BWI is coordinating response with state and federal authorities. It's the same approach they took a few years back with the SARS outbreak.

Meanwhile, here are 7 things you need to know about swine flu. And is it safe to fly during the swine flu outbreak?

Photo: Deserted Mexicana Airlines counter at San Francisco International Airport. Ben Margot, Associated Press