By JOHN RICHARD SCHROCK
Two masters biology students in my department needed to research prairie dogs some years ago—they had to receive expensive vaccination shots against bubonic plague. The range on prairie dogs is the Western U.S., west of a line cutting north and south through Hutchinson, Kansas. But bubonic plague was a dreaded disease of the Middle Ages in Europe, once killing up to 60 percent of the population in the 1300s. How did this plague come to North America?
Plague has its ancient origins in the Vietnam region, where the bacterium Yersinia pestis exists in wild rodents. We know it has resided there the longest because as a zoonosis, a disease that circulates in wild animals, the host animals are nearly immune to it. Fleas carry it from one host rodent to another. As humans traveled by ship, so did rats. Fleas infected the rats that eventually got sick and died. Fleas then left the dying rats and bit people. That is how it would spread into India, the Middle East and into Europe. North America was protected because sailing ships were slow.
But steamboats were faster. And a plague that swept through southern China in the 1890s was spread to Hawaii. Some ships carried casualties of plague, but they died on board. But when infected rats arrived and died in San Francisco in 1900, the fleas jumped to people. Plague had arrived in America.
Bubonic plague is caused when bacteria are filtered out and infect the lymph glands under the arms and groin, producing large “buboes.” In the blood, it is septicemic plague. Both are transferred by fleas. Both were mostly fatal. But when the bacteria infect the lungs, coughing spreads plague person-to-person.
American medical workers recognized the cases of plague in March of 1900. But California Governor Henry Gage denied this plague existed. He was more concerned with California’s business image and any loss of revenue a quarantine might cause. Federal authorities came in and confirmed the infections. Yet negotiations with Surgeon General Wyman and President McKinley allowed the suppression of this report by disease experts. But newspapers spread the truth and Gage lost the 1902 election. The new governor took action and stopped the epidemic by 1904 after 121 cases with 119 deaths.
But the 1906 earthquake and massive fire of San Francisco resulted in a surge in rats and a second outbreak of plague city-wide. By 1908, there were 160 more human cases and 78 deaths. Rat eradication continued until 1911 when cases subsided. But by then, fleas had also infected wild rodents (sylvatic plague). That is how plague came to be spread across the Western United States and why the two biology masters students needed to get vaccinations to work with prairie dogs.
Prairie dogs, being a new host, may suffer over 90 percent mortality from plague outbreaks. The CDC estimates from one to 17 humans, mostly hikers, get plague each year from contact with infected prairie dogs. If caught early, it is well-treated with antibiotics. But plague also contributes to the black-footed ferret, a predator of prairie dogs, being endangered.
One lesson California Governor Gage did not learn is that it is foolhardy to contradict science. If you deny a disease’s seriousness, nature will prove you wrong.
However, we should be careful not to extrapolate our plague history with the current outbreak of COVID-19. China is not the United States in population nor in culture. Their huge population is living in far closer quarters. Wherever you see one person in the U.S., envision five in China. When the winter flu season arrived, the symptoms of influenza were identical to the initial symptoms of COVID-19. And in their close quarters, crying “wolf”—just like crying “fire!” in a crowded theater, is dangerous and can result in panic and disruption of its own.
It is outstanding that the young Chinese medical doctor detected this new viral infection in the midst of a normal flu season. The suppression of his alarm was very brief and wrong. But from what we know now of this coronavirus, it would not have prevented the eventual spread. Having suffered through the similar 2003 SARS event, Chinese officials are much more aware of the dangers of denying science. Indeed, if you want to hear this type of science denial, you only need to turn on certain radio stations in the United States today. You can still hear the echoes of a modern Governor Gage.
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John Richard Schrock has trained biology teachers for more than 30 years in Kansas. He also has lectured at 27 universities in 20 trips to China. He holds the distinction of “Faculty Emeritus” at Emporia State University.