A Worm That Can Really, Really Get Under Your Skin

It sounds like a scene straight out of a nightmare.

One morning you wake up and something is crawling beneath your skin. It wriggles and writhes across your face, seemingly ready to rip out of your skin at any second. (Anyone remember that one scene from the movie Alien?)

But this, my friends, is no nightmare. It is a very real possibility — and a recent reality for one woman infected with Dirofilaria repens, a parasitic worm of the Old World. In her gruesome case described and shown through pictures on Wednesday in the New England Journal of Medicine, the woman in Moscow had to have the worm surgically removed from her lip.

How did a worm end up beneath a woman's skin?

It all starts with a bite from a mosquito that's carrying the worm's larvae, says Natalia Pshenichnaya, a physician who studies infectious diseases at Rostov State Medical University in Rostov, Russia. The mosquito picks up the larvae from a host: "dogs and other carnivores."

When an infected mosquito sips your blood, the parasitic larvae latch on to your skin and enter through the bite wound. Eventually, the larvae grow — and can start moving, Pshenichnaya says. (Usually only one enters, but there have been cases of several worms wiggling in.)

In about a fifth of cases that she has seen, the worms "move considerable distances," Pshenichnaya wrote in an email to NPR. For example, from the knee to the groin area or from the upper eyelid to the buttocks.

In the case of the patient in Moscow, the woman documented the worm's two-week lifespan beneath her facial skin by taking selfies. It started as a small nodule below her left eye. Five days later, the woman snapped a shot of three bumps above her left eye. Ten days later, the nodule appears larger and is located in her upper lip.

Other than a sense of itching and burning near the site, she had no symptoms.

That's usually how it goes. Patients report pain, redness, swelling and a "feeling of crawling under the skin" at the site, Pshenichnaya says. She adds: "Let's note that this disease doesn't cause any serious problems for human health."

The woman ended up being treated by Vladimir Kartashev, a physician at Rostov State Medical University. Using a pair of forceps, Kartashev held the worm in place and surgically removed it from her lip.

The size of that worm was not revealed, but females can grow up to 6.5 inches long, while males grow to nearly 3 inches.

Kartashev and Pshenichnaya both say the case was not surprising. They have seen it before.

Since 1997, "we already have around 4,000 patients [in the former USSR territory] and in nearly half of them, the parasite location is the face, including the eyes," Kartashev wrote in an email to NPR.

It's not just happening in Russia. Infections have occurred in Austria, France, Hungary, Italy, Romania and Ukraine, according to the European Society of Dirofilariasis and Angiostrongylosis (ESDA). The worm has also infected humans in Africa and Asia.

Claudio Genchi, a veterinary scientist at the University of Milan, says the number of these infections "is dramatically rising in the West."

In a paper he published last year, he wrote that more than 3,500 cases were reported in Europe between 1977 and 2016, and today, D. repens has become "a serious public health concern." Genchi suspects part of the infection's spread is due to climate change and more favorable warm-weather conditions for the mosquitoes that transmit the disease.

That being said, mosquito repellent is key, especially from the end of spring to the beginning of autumn when mosquito activity is at its peak, Pshenichnaya says.

If worse comes to worse and you find yourself infected, surgical removal is the preferred method of treatment — like the woman in Russia — but you can be treated with albendazole, an antiparasitic drug, too. Otherwise, the worm can live in the human body for about two years ... crawling right beneath your skin.

There is one glimmer of good news. It can't reproduce inside of you, Pshenichnaya says.

Nadia Whitehead is a freelance journalist and science writer. Her work has appeared in Science, The Washington Post and NPR. Find her on Twitter @NadiaMacias.