Awww — Isn’t the Plague Cute?!

Mexican ground squirrel
Spermophilus mexicanus

My wife has taken a job as a teacher’s aide with a local elementary, as she awaits that first real teaching job. Yesterday, a teacher had caught something on the playground and put it in a fish bowl. Taking a look at it, she asked him, “Do you know what that is?” He answered it was a ground squirrel. “Do you know what kind?” He didn’t. “I believe it’s a Mexican ground squirrel. I think the scientific name is Spermophilus mexicanus… I’m married to a biologist,” she added as way of explanation.

Spermophilus mexicanus. My heart swelled with pride. How did she learn such valuable information? I haven’t forced her to remember any taxonomy. Naturally, as any good biologist does, I use it where ever I can, mainly for myself so that I can remember. But how she remembered it, I confess, I do not know.

That evening after telling me the story, she asked if I thought there was a risk of rabies. “There certainly is,” I replied. “There’s a risk of plague too.”

My wife looked at me in surprise. Like most people probably do, she thought plague was something of the past that doesn’t affect the U.S. Though I remembered few details, I knew it was still around in the fleas of some rodents, and that each year a small number of Americans get infected.

I decided to do the most basic of research. From the CDC’s site on plague, I learned that Spermophilus mexicanus is likely a perfect vector.

Rock squirrels and their fleas are the most frequent sources of human infection in the southwestern states. For the Pacific states, the California ground squirrel and its fleas are the most common source.

What the CDC left out was the classification of those two squirrels. Spermophilus variegatus and Spermophilus beecheyi respectively. Thus they are very closely related to Mexican ground squirrel. The CDC continues:

Many other rodent species, for instance, prairie dogs, wood rats, chipmunks, and other ground squirrels and their fleas, suffer plague outbreaks and some of these occasionally serve as sources of human infection.

Now, not wanting to sound alarmist, I should note that the chances of getting infected are very low.

In the United States during the 1980s plague cases averaged about 18 per year. Most of the cases occurred in persons under 20 years of age. About 1 in 7 persons with plague died. [and elsewhere] In the U.S., 1 to 40 cases reported annually (avg = 13 cases) by western states, 1971-1995.

There also have been very few cases of plague that have turned up in Texas, though apparently God is smiting New Mexico and Arizona.

Still, it might be a good time for the teacher to let the poor critter go. Perhaps parents would feel a little better with a hamster, no?