Creeping eruption is a hookworm infection of the skin. The skin is invaded by the larvae of the dog or cat hookworm. This causes a thread-like line of inflammation that moves in a "creeping" form over time.
Creeping eruption occurs when human skin comes into contact with soil contaminated with cat or dog feces that are infected with hookworm. The eggs of the hookworm are passed in the feces, and hatch into larvae. The larvae penetrate human skin and begin to wander through the layer below the skin.
Creeping eruption usually affects a person who plays or works in shaded, moist, sandy areas that have been contaminated with animal feces. Children and farmers are at greatest risk. It is more common in warm, humid areas, including the southeastern United States.