Most skin issues like itching, redness, or swelling are harmless and short-lived, often caused by insect bites or allergies. However, in rare cases, unusual or persistent skin changes may indicate a subcutaneous parasitic infection—a condition where parasites live temporarily beneath the skin. Though uncommon, these infections are medically significant and worth understanding.

One widely discussed case occurred in Russia in 2018, when a woman noticed a shifting bump on her face. Initially believed to be a mosquito bite, the bump migrated from under her eye to her lip. Doctors discovered a Dirofilaria repens worm, typically found in dogs and transmitted by mosquitoes. The parasite was removed surgically, and the patient recovered fully. This case, published in the New England Journal of Medicine, highlighted how subtly such infections can present.

Subcutaneous parasitic infections occur when parasites normally found in animals or specific environments enter human skin. Although humans are often “dead-end hosts”—meaning parasites can’t reproduce inside us—they can cause symptoms like itching, redness, swelling, or a crawling sensation.

Examples include Onchocerciasis (blackfly-transmitted and potentially blinding), Cutaneous Larva Migrans (hookworm larvae causing red, winding skin lines), Loiasis (eye worm seen in West Africa), Swimmer’s Itch (from lake water), and the now-rare Guinea Worm Disease.