WASHINGTON • First, it appeared as a tiny blemish under the eye.
But over the following two weeks, the 32-year-old woman watched it move, snapping photos as it formed bumps above her eye, before it made its way down into her lip, forcing her mouth to swell.
It was a parasite - and it was living inside her face.
The case as well as shocking images were published last Thursday in a report - titled Migrating Dirofilaria Repens - in The New England Journal of Medicine, detailing a case in which a woman from Russia became host to a parasite through a mosquito bite.
The report states that the woman, who was not named, started showing symptoms after travelling to a rural area not far from Moscow, where she "recalled being frequently bitten by mosquitoes".
Dirofilaria repens is a long parasitic roundworm that is spread by mosquitoes, according to the Centres for Disease Control and Prevention.
Dr Thomas Nolan, director of the clinical parasitology laboratory at the University of Pennsylvania School of Veterinary Medicine, said mosquitoes ingest the microfilariae (the parasite's undeveloped embryos), which then travel to the insect's gut and mature into first-, second-and third-stage larvae.
The larvae then make their way into the mosquito's mouth parts and, Dr Nolan said, when the mosquito bites an animal - or a human - they crawl quickly into the bite site.
Once in their new host, he said, the larvae mature into adult worms.
Such parasites are said to be an emerging disease in the western part of the former Soviet Union and in certain parts of Europe.
That said, the parasites usually die in the skin and are easily removed. The case report said doctors in Russia surgically removed the worm from the woman's face, and she recovered. Well, at least physically.