Swine Flu: How Disease Travels

Here's an interesting map of the current outbreak of Influenza that originated in Mexico and has now traveled to the United States, Canada, and New Zealand. There are suspected cases in Europe and Israel, all linked to recent travel to Mexico. There are confirmed cases across the U.S., most recently in New York and Ohio.

According CBS News, the new virus "contains human virus, avian virus from North America and pig viruses from North America, Europe and Asia." It's rare to see such a mix of genetic material from such widely spread geographic areas. Scientists are still unsure how the disease is spreading; normally, swine flu involves direct human contact with infected pigs, and doesn't easily spread from person to person. However, this outbreak seems to involve people who have had no contact with pigs, and little or no contact with each other.

Of further concern is the large number of deaths in Mexico that are being attributed to this virus, although no deaths - so far - have occurred outside of Mexico. One theory is that the normally vulnerable groups - infants, the elderly, and those with compromised immune systems - have had their seasonal flu vaccines, giving them a limited protection against this outbreak, or at least lessening the severity of symptoms.