World governments should be careful not to play politics with the Mexican swine flu outbreak. The health consequences should of course be rigorously addressed—but without adding economic consequences, which is what several countries appear poised to do.

Public health scares have a history of seeping into trade policy without anything resembling sufficient consideration of the evidence. Governments in Russia and East Asia are already banning pork exports from Mexico, even though there is zero evidence that they pose a health hazard. It hearkens back to unfounded bans of U.S. beef in recent years by the European Union and South Korea.

If the U.S. government jumps on board, U.S. exports could be targeted for retaliatory trade actions. One quarter of U.S. pork production is exported, as well as billions of dollars of our soybeans used as feed by foreign hog farmers.

Exploiting this crisis could turn what is so far a manageable health problem into an unnecessary trade and diplomatic conflict. Obviously the global economy does not need the extra strain.