Speed of the Spread of Flu Is Linked to Airline Travel
By NICHOLAS BAKALAR
Published: September 12, 2006
Airline travel has a significant effect on the spread of influenza, a new study reports, raising the question of whether flight restrictions may be helpful in controlling a pandemic.
Although computer simulations have already suggested a link, this study, published online yesterday in PLoS Medicine, offers the first observations of the phenomenon.
The researchers compared the timing and number of influenza deaths in 122 American cities with the volume of airline travel during the same period for each of nine flu seasons, 1996 to 2005. They found that changes in the rate of spread and the timing of peak mortality each year correlated with yearly fluctuations in monthly airline passenger volume.
Domestic airline travel in November was the best predictor of the speed of influenza spread, the researchers found, although influenza infections and deaths usually peak in late February.
They suggest that travel during the Thanksgiving holiday may be the central event in determining the rapidity of transmission. The fewer domestic airline passengers there are, researchers found, the slower the flu moves across the country.
This effect was particularly pronounced after the Sept. 11 attacks, when a temporary flight ban was instituted in the United States and airline travel volume was lower than in any other season from 1996 to 2005.
In most years, the peak date for influenza mortality in the United States occurs within two days of Feb. 17. But in 2002, the peak date was almost two weeks later, on March 2.
In 2003, 2004 and 2005, the peaks gradually returned to the normal range, Feb. 29, 19 and 17, respectively.
Full ArticleThis article is less morally saturated than my other posts, but I thought it was interesting to think about globalization as spreading as many diseases as goods and services. Imagine if the world was as connected during the time of the Black Death; would any one have survived? If the rat flea vector really did spread the disease, possibly on ships, imagine how much faster that would have happened if even a few sick people boarded airplanes and went off to other countries.
Something as common as influenza, once used in combination with smallpox to eliminate Native American populations, is now spread across airplanes from city to city and country to country. This is just one of the many little ways that the world is becoming connected that most people don't even think about.