Skin worms, a parasite known for it's anesthetic enabled stealthy infection of the body's skin, takes part of the blood flow from the skin of the area it infects and grows until it covers vast portions of the body's exterior. Afterwards it lays eggs...
Report to your nearest medical staff if you feel partial numbing or tingling for a prolonged period on your body after sleeping in the field or after engaging in deep foliage camouflage procedures, you don't want to reach the eggs part.