Cutaneous larva migrans. Raised area in a patient's back caused by burrowing larvae of the dog hookworm (Ancylostoma sp.). This tropical parasite normally infects dogs. The worm's eggs hatch in dog faeces, releasing larvae into the soil. The larvae can penetrate unbroken skin when it comes into contact with the ground, for example a dog's paw or a human's foot. The larvae can survive for several months in humans, although they are not the natural host. The larvae burrow around under the surface of the skin, causing a severe localized allergic reaction known as creeping eruption. The infection can be treated by anthelmintic drugs.