"The Plague": Why News of this Disease is Nothing New

The Plague, that is, an infectious disease caused by the bacterium Yersinia pestis, ravaged Europe during the 1400s, where it was known as "the Black Death" and claimed the lives of tens of millions of people (a third of the population!). Recently, alarmist news headlines reported instances of the plague being diagnosed in the United States, causing many readers to believe that another possible pandemic could result. It should come to everyone's relief that this news is not news at all: The United States sees on average 7 cases of the plague each year, every year. The difference from medieval Europe? Antibiotics and infection control. 

Yersinia pestis is a gram-negative coccobacillus that causes bubonic plague via flea bites, pneumonic plague via another infected individual, and septicemic plague, also spread by flea bites but affecting the bloodstream. This bacteria spreads easily among rodents, specifically rats, where it causes a mild and non-lethal infection. Rats brought the bacteria to Europe via trading ships, and fleas that bit the rats also bit humans, thereby transmitting the disease, where it caused the lethal disease that ravaged the population.

In the early 1900s, rats also brought Yersinia pestis to the United States via steamships, causing epidemics in port cities and leading to the infection of local rodents, including prairie dogs. The bacteria continues to circulate amongst these rodent communities, specifically in northern New Mexico and Arizona, southern Colorado and Oregon, far western Nevada, and California. 

Also in these areas of the US? All cases of plague, which tend to occur in rural areas where humans come into contact with infected rodents. Since 2000, there have been 120 cases of the plague, with 15 deaths. There are, on average, 7 cases of the plague in the USA per year, every year. The great majority resolve with excellent outcomes thanks to antibiotics. There is even a vaccine, although it is currently under redevelopment in the US. So all in all, these headlines are nothing new, and nothing to be fear.

Sadly, headlines like those mentioned above lead some bad actors to use misinformation to place blame on immigrants for the disease. This is also nothing new: Immigrants have historically been falsely blamed for disease for millennia, including in the United States. When the plagues brought by steamships first hit San Francisco as mentioned above, the Chinese immigrants were blamed and quarantined when the first cases spread among this population (it was a case of officials denying the disease and scientists trying to stop an epidemic, but that's another story). The reason the plague spread more easily among this population was not their nation of origin or disease status on arrival but rather the poor living conditions to which they were relegated. Even today, regions of the world with poor living conditions, where rodents are a fact of life, see a much higher rate of plague cases. As with every other communicable disease, improved infection prevention and control, including hygiene, clean surfaces, and prompt treatment makes all the difference.

It may seem like a logical step to look at cases of plague in the western United States and blame immigration from the Mexico/US border, legal or otherwise. But it is important that we all keep in mind that any claims that this is true are completely and (scientifically) unsubstantiated. Just like any claim, but especially claims involving our health and safety, it is imperative that we stick to the facts and what the data tell us. While most claims are regulated by the EPA and/or FDA, bad actors do make their way across the airwaves and it can get confusing. Do immigrants sometimes arrive to the US sick? Of course. (So do immigrants from wealthy countries, mind you.) Immigrants, especially refugees and those who have enduring arduous travel by foot before crossing the border illegally, often struggle with poor health. This makes sense: They have been through unimaginable physical strain, lacking in water and food, and living in unhygienic conditions. Immigration screening, refugee centers, and border region health outreach identify and treat these health conditions very effectively. All the cases of plague in the US have been US citizens, contracting the disease from pet cats (who hunt rodents), or flea bites, not immigrants.

What kind of conversations are you hearing surrounding the plague this year? Share your experiences in the comments below!