A passenger takes a photo of Mexicana Airlines staff at the international airport in Buenos Aires April 30, 2009. The World Health Organization said on Wednesday the world is at the brink of a pandemic, raising its threat level as the swine flu virus spread and killed the first person outside of Mexico, a toddler in Texas. Argentina and Cuba have halted flights from Mexico and the United States has advised against nonessential visits to its southern neighbor. REUTERS/Enrique Marcarian (ARGENTINA HEALTH TRAVEL)