Plague in Mongolia! Plague in Colorado! Should We Be Worried?

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Photo by conor rabbett on Unsplash

Uh oh. We appear to have an outbreak of plague in Mongolia. Last thing we need, right?

Oh, and it’s been found in squirrels in Colorado. Eep! Scary!

Let’s unpack this and work out whether we really need to be worried.

What Causes the Black Plague?

The “actual” plague, which comes in bubonic, septicemic and pneumonic variations is caused by a bacteria called Yersinia pestis.

This bacteria is, like COVID-19, essentially zoonotic. It’s endemic in multiple species of rodent and is transmitted primarily by infected fleas (both rodent fleas who accidentally bite humans and potentially human fleas who accidentally bite rodents). It can also sometimes be found in rabbits and in carnivores that eat affected animals. This includes cats, making it yet another reason not to let kitty outdoors. In fact, cats are particularly susceptible and can then sometimes pass it to their owner. Dogs and cats can both bring infected fleas into the home.

Generally, it starts off as bubonic plague, which infects the lymphatic system. Septicemic (blood) and pneumonic (lung) variants occur if it’s not treated promptly.

Although it can spread between people in close contact, this is rare and has not been documented in the United States since 1924.

But the Plague Went Away Years Ago?

Nope! There are between one and two thousand cases of plague every year. In the United States, the number of cases per year averages 7. Most cases are hikers in the back country in the American west. The disease is also endemic in prairie dogs, sometimes causing small outbreaks in farming communities.

Yersinia pestis hasn’t gone anywhere. It’s not extinct. It hasn’t been eradicated.

What’s different is that plague is now treatable. Modern antibiotics mean a 90% survival rate and because we now know how it’s transmitted, it’s easy to isolate and control outbreaks. We don’t have a vaccine (although we’ve been working on one. Vaccines against bacterial diseases are hard), but we can treat it.

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Photo by Miguel Teirlinck on Unsplash

So, this Won’t Be Another Pandemic?

Nah. Mongolia is another location that tends to get occasional cases crop up. Authorities have instituted a temporary ban on handling, hunting, and transporting animals that might carry plague (in this case, it appears that it was caught from marmots).

There were two cases, one a farmer, the other a teenager who was hunting marmots.

Last year, there were also two cases in Mongolia, caused by eating raw…marmot.

Which clearly tells us it’s endemic in marmots there. This isn’t going to cause an epidemic because it’s an old, familiar disease which we know how to handle and is not particularly contagious person to person.


Don’t touch wild rodents.

And please keep your cats indoors if you live somewhere where plague is known in the wild rodent population. Treat your cats and dogs for fleas regularly.

And don’t worry about the Black Death. That particular reaper’s scythe has been well and truly blunted.

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Freelance writer, freelance editor, novelist and short story writer. Jack of many trades.

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