John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
The allergy-causing organisms commonly latch on to our luggage, clothes, and (gag) food.
That airplane seat might look empty. But whip out a powerful microscope and you could spot this girl, perusing a microns-wide piece of SkyMall:
Oh, hello there—it's everybody's favorite skin flake-eating organism, the common dust mite. These little fellows, so despised for causing sneezing, itching, facial pain, and other allergic reactions in up to 130 million world citizens, are ubiquitous; they've been caught living it up in environments as extreme as the Antarctic and the International Space Station. It shouldn't be a surprise, then, that they're also using our jet planes to commute from country to country, as detailed today in a new paper in PLOS ONE.
The mites are now notorious for living on pillows, blankets, carpets, and other household surfaces, munching on dust and sloughed epidermis and other delicacies. But they traveled far over time and space to attain this comfy perch, having millions of years ago resided in birds' nests. Over their great journey, the mite clan has split and split again, fractioning into genetically unique populations. It's these DNA variations that allowed scientists at the University of Michigan and elsewhere to surmise they're traveling through the air: They detected a rare mutation in American mites connected to a tiny colony in Pakistan.
So how might they be sneaking aboard? The mites can hitch rides on our luggage and even packed lunches, according to the researchers:
"What people might not realize when they board a plane is that they can share the flight with a myriad of microscopic passengers—including house dust mites—that take advantage of humanity's technological progress for their own benefit," said U-M biologist Pavel Klimov.
"House dust mites can easily travel on an airline passenger's clothes, skin, food and baggage," said Klimov, an assistant research scientist in the U-M Department of Ecology and Evolutionary Biology. "Like humans, they use air travel to visit new places, where they establish new populations, expand their ranges and interact with other organisms through various means."