This is the true story of one of the last outbreaks of bubonic plague in history. It is also the story of one of the first triumphs of modern medicine.
It began in the interior of China. In 1855, a military revolt broke out in Yunnan. Chinese troops were sent to the area to suppress the rebellion. Unfamiliar with disease risks in the area, they contracted the bubonic plague and then returned back across the Salween River to spread the disease to the rest of China. Following this, the disease rose up in occasional outbreaks through 1894, mainly in the Chinese interior, and attracted little attention from the rest of the world. The death of peasants from a common disease in an overpopulated nation was hardly noteworthy.
In 1894, the disease reached Canton and Hong Kong, where several European powers had ports. A chill went through the international community. This was a time when memories of Louis Pasteur and Robert Koch were still fresh; bacteriology was in its infancy, but hordes of doctors and philanthropists were interested in the new medical revolution.
International medical teams were dispatched to China immediately. Within a matter of weeks, two separate doctors (French and Japanese) identified the bacterium Pasteurella pestis, the bacillus of plague. Over the next few decades, as the plague outbreak continued, the details of plague transmission (fleas to rodents to men) would become firmly established by international medical teams operating in places as farflung as Sydney, Bombay, San Fransisco, and Buenos Aires (not to mention the Chinese outposts).
Suddenly, the implications of a highly infectious disease in a global economy became apparent. Within a decade of the plague's arrival in Hong Kong, all of the major seaports of the world experienced outbreaks. Mainly, the disease was quickly contained, but in Bombay it was not; in ten years, the terrible disease spread throughout India and over six million deaths were reported. This spurred yet more research (mainly because of British interests in that colony).
Another important discovery was made: in California, South Africa, and Argentina, burrowing communities of wild rodents picked up the plague bacillus even more readily than people. In 1900, California ground squirrels were discovered to be infected; that was also the year that there was a first outbreak of plague in San Fransisco (in Chinatown). The plague disappeared quickly among humans through medical efforts such as quarantine; however, it remains endemic even today in the rodent communities. In fact, every year since 1900, the plague has been infecting new rodent populations, spreading outward from San Fransisco. By 1975, nearly all of North America's rodents were infected by a bacillus that had come seventy-five years hence from San Fransisco. (This was not entirely the result of nature-- ranchers would transport rodents infected with the plague across the country in the back of their trucks in an attempt to infect and eradicate native destructive rodent populations, such as prairie dogs and gophers. As a result, every year a few North Americans contract plague and occasionally die from the bite of a wild rodent's fleas.)
Following 1900, human plague occurred sporadically in North America, Argentina, and South Africa. Mortality rates were about 60% until the 1940's when the discovery of antibiotics made it easy to cure (if detected in time). These minor outbreaks attracted little attention, often because they were so minor, and because local governments wanted to hush up reports of such a terrible disease in their region.
In Manchuria however, major outbreaks continued to occur. The first was in 1911 and the second ten years later, in 1921. Again, international doctors reported to the scene. They quickly discovered that the humans were contracting plague from fleas on local marmots. These marmots were being hunted for their pelts, which commanded high prices on the international market (again, the global economy comes into play...). For centuries, local hunters had used myths to stay disease free; no doubt these myths originated from observations of epidemiological effects. The animals had to be shot, from a distance, rather than trapped; a slow moving animal, or one who seemed sick, could not be hunted. If a colony of marmots seemed sick, the humans who were hunting them immediately had to leave.
In 1911, politics destroyed tradition. The Manchu Dynasty was struggling towards its final collapse, and the government's regulations against Chinese moving into Manchuria broke down. These new immigrants immediately discounted the legends surrounding marmots as stupid and superstitious; they trapped without thought, and were soon teeming with infection. The plague spread down new railroad lines to the urban area of Harbin.
What prevented this outbreak from spreading further, from port to port, around the globe, killing millions, just like its historical predecessors? The answer is simply: modern medical science.
This entire chain of events had been carefully observed and recorded by the international scientists. Everything from patterns of infection to the life cycles of rodents had been taken into account, information had been gathered, conclusions drawn. As a result, great epidemiological disaster had been stopped. Quarantine and preventative measures occurred. There is also one side conclusion that is important enough to be listed here:
The bacteria Pasteurella pestis is always looking for a new host; slow boat rides either kill off all the suitable hosts (which is why the Black Death was only spread by ship across small expanses of water, and was spread more by land lines of infection such as caravans, where travelers carrying the disease often had to stop at outposts where lots of other people were waiting to be infected) or infect them and give them immunity. However, during the 1870's a new wave of ship travel came about: the steamship network spanning the globe. These fast-travelling ships could carry the disease across an ocean to new ports and new people waiting to be infected.