Many people assume that the 2009 H1N1 pandemic spread rapidly across the globe largely due to the sheer number of people hopping onto planes. But more than 120 years ago, trains and ships alone sped the transmission of the 1889 "Russian" flu so that it reached the U.S. 70 days after the virus' first peak in St. Petersburg and circled the globe in just a few months, according to a new analysis of historic data.

The 19th century might seem distant and disconnected compared to today's planes, trains and automobiles. But by the time the 1889 Northern Hemisphere flu season arrived, more than 202,800 kilometers of railway connected 19 European countries and ships steamed across the Atlantic in less than a week, noted the authors of the new study, published online April 16 in Proceedings of the National Academy of Sciences.

The findings, gleaned from historic health records and surveys, highlight the capacity of a virus to travel quickly even without high-speed air and automobile travel. "The rapid progression of the 1889 pandemic demonstrates that slower surface travel, even with much smaller traveler flows, sufficed to spread the pandemic across all of Europe and the United States in [about] four months," noted the researchers, led by Alain-Jacques Valleron of the Institut National de la Santé et de la Recherche Médicale in Paris. This conclusion is backed up by more recent mathematical models that suggest the connectedness of cities is a more important factor than quantity of travelers in determining pandemic spread.

Researchers have a solid sense of the spread of influenza pandemics in 2009, 1968, 1957, 1918 (and now 1889). But these account for fewer than half of the known flu pandemics from the past three centuries. As more information comes to light about previous pandemics, researchers and governments alike will be able to better predict and plan for possible dynamics of future outbreaks.

Although the Russian flu was relatively mild for a pandemic strain—closer in virulence to the 1957 and 1968 flus than to the 1918 variety, the authors noted—it still took a heavy toll, killing an estimated one million people.

For both spread and virulence, the 1918 pandemic has been "de facto the stereotype of the feared pandemic to come," wrote Valleron and his colleagues. But the new analysis of the 1889-90 data underscores the notion that the 1918 flu was an exception rather than the standard of global influenza pandemics, and in fact, the 2009 H1N1 strain "seems to be another 'mild' pandemic, similar to what our analysis revealed the 1889 Russian flu to be."

image of train pulling out of the Bahmi, Turkmenistan station on the Trans-Caspian Railway around 1890 courtesy of Wikimedia Commons