September 13, 2012
Japan in the time of cholera
From the mid-19th century to the early 20th, Japan experienced cholera epidemics on the scale of the 1918 flu pandemic. Controls on internal migration during the Edo period vanished after the Meiji Restoration. The ancient sewers couldn't handle the exploding urban populations.
Japan suffered at least seven major outbreaks of cholera between 1858 and 1902. The Ansei outbreak of 1858-60, for example, is believed to have killed between 100,000 and 200,000 people in Tokyo alone.
(The Ansei epidemic figures prominently in the time travel series Jin, as our valiant doctor from the future battles the outbreak with 21st century knowledge and 19th century resources.)
In a perverse irony, the situation was worsened by endemic beri-beri, which came on the heels of dietary "improvements" (increased production and consumption of polished white rice), though the recurring famines of the past two centuries ceased.
(Dr. Jin Minakata invents the thiamine-enriched doughnut to address that problem.)
Japan's sudden opening to the west also meant that "foreign" pathogens were being introduced into the population at a velocity the Japan had never experienced before. Its last contact with Europe in the 16th century was a trickle by comparison.
But it was a foreigner who came to the rescue. I've heard Japanese unironically compare the British engineer W. K. Burton, who designed Tokyo's first modern sewer system, to Jesus.
Japan now boasts one of the healthiest populations on the planet. In the long term, I think the speed and extent of international travel has actually reduced the odds of a 1918 flu epidemic happening today.
As Matt Ridley points out in Wired Magazine, apocalyptic epidemics now have the habit of evaporating like desert mirages. There aren't any truly "virgin" populations left for viruses to work their havoc on. The mills of Darwinian selection grind slowly but inexorably.