In recent days, U.S. security officials have been urged, vehemently at times, to close the border with Mexico. Cruise lines have canceled stops along that country's coast. France asked the European Union to halt flights there. And one European health official even suggested that travel to the United States be avoided.
But here's the problem with such attempts to stop, or slow, the spread of the new H1N1 flu strain: Viruses don't grasp the concept of borders.
Attempting to seal off nations -- an inclination of many people and even some countries in the recent outbreak -- will prove futile not only now but in the future, experts say. Such measures cause unnecessary panic and economic harm, infectious disease experts say.
By the time a virus has been identified as a potential threat, it's probably already traveled far beyond its source, especially with today's mobile population.
Besides, obvious symptoms lag behind actual infection, meaning many people can be spreading the illness before they know they're ill.
"These actions really don't make sense," said Dr. Christian Sandrock, an infectious diseases expert at UC Davis Medical Center. "The benefits in lessening the spread of disease do not outweigh the economic and social problems these things cause."
Shutting down ports of entry between nations and attempting to control the movements of an area's residents are unlikely to halt transmission of a virus once it has spread beyond the first few cases of infection, epidemiologists say. Mathematical models and experience from the 2003 SARS outbreak support those findings.
"You really can't prevent the spread of these things by closing a border," said Dr. David Freedman, a spokesman for the International Society of Travel Medicine and a professor of medicine at the University of Alabama. "At best, physically closing a border could delay the spread of a disease by a few days. Travel restrictions are really ineffective."
Air travel has been shown to be the most influential mode of transmission in disease outbreaks, and an estimated 2,600 international flights land in the United States each day.
"Airplanes are silver tubes in which we put bugs from one country and send them to another country," said Dr. Sandro Galea, director of the Center for Global Health at the University of Michigan.
