As the coronavirus pummels the United States in 2020, Albert Camus’s 1947 novel La Peste (The Plague) has slipped back onto the bestseller lists. It tells the story not of an airborne virus, though, but the bubonic plague. We will look at the history of plague in the United States, a country with which the plague is not commonly associated but nonetheless has experienced outbreaks of its own.
The plague is caused by a bacteria called Yersinia pestis and is transmitted by fleas. Such fleas spread the infection to animals and humans; human-to-human transmission is rare.
The plague came to the United States in 1900 by steamships infested with rats. The first American to die was San Franciscan Wong Chut King, and his autopsy confirmed that it was indeed plague. The epidemic lasted for about eight years, with 280 reportedly infected and 172 dead. Many of the earliest deaths were in the city’s Chinatown neighborhood, resulting in intense prejudice against its denizens.
While doctors and other public health officials in San Francisco tried to rouse attention, they were often stymied by city and state officials, who worried about damage to the economy. Such officials, including Governor Henry Gage, also rejected the new type of science, medical bacteriology, that the central doctor working on the plague cases—Dr. Joseph J. Kinyoun—was pioneering. Kinyoun sent memos to the federal government and out-of-state newspapers began to pick up the story, even as California’s political and business leaders refused to acknowledge the plague’s presence. After Kinyoun was transferred to Detroit, Dr. Rupert Blue was appointed his successor. Blue was a better communicator and managed to implement initiatives to clean the city and eradicate the rat population, thus ending the epidemic by 1908.
The last urban plague epidemic was in Los Angeles from 1924-1925. It lasted about two weeks and killed 30 people. Public health officials credit the city’s use of lessons from the San Francisco outbreak, such as hospitalization of the sick and their contacts, quarantine, and a rat-eradication program, with forestalling the epidemic from spiraling much higher.
According to the CDC, since 2000 there are about 1-17 cases per year. In 2016, for example, there were 4 cases. The cases are mostly prevalent in the western United States. According to a Pacific Standard article, “while the exact causality of the disease's geographic concentrations is not yet settled science, [biologist David] Markman points to average soil moisture and the presence of burrowing rodents like prairie dogs as potential factors. [Biologist Nils Christian] Stenseth, too, believes the answer may lie in the dirt, a factor that might be related to the evidence that climate change is increasing outbreaks in some areas, and decreasing them in others. ‘My hunch is that might be something about the soil properties, that it's not too dry, but it's not too wet either, very humid,’ Stenseth says. ‘It always occurs in rodent species, typically in a burrowing species. These colonies are usually quite humid. But I don't know, and the scientific field doesn't know.’"
Most cases in the United States, if treated, are not fatal anymore. Popular Science writer Claire Maldarelli explains, “Despite its ability to turn deadly fast—the bacterium has an incubation period of a few days, and when it does kill it does so in one to seven days—the infectious Yersinia Pestis is also very responsive to antimicrobial drugs. Prior to the discovery of antibiotics in the 1940s, the plague killed about 66 percent of those it infected, especially people who were already sick and the elderly. But once we had drugs that could treat it, those numbers dropped drastically. Today, in the United States, the plague turns deadly only in about 11 percent of cases.”