PARASITES — SCHWARTZ 431 



the epithelial layer rather severe lesions, with accompanying irritation. 

 In the United States a skin condition known as creeping eruption is 

 caused by the penetration and subepithelial migration of dog and cat 

 hookworm larvae of the species Ancylostoma hraziliense. Creeping 

 eruption is fairly common in the coastal regions of the South where 

 A. hraziliense also is common in the intestines of dogs and cats. In 

 these carnivores the hookworm larvae develop to the adult stage, fol- 

 lowing their entrance into the body through the skin and their subse- 

 quent migration to the lungs via the blood stream. From the lungs the 

 larvae reach the small intestine by upward migi-ation in the respiratory 

 system until they get to the pharynx and mouth, and go from there to 

 the stomach and so on to the intestine. A. hraziliense is a rare parasite 

 of the intestine of man because the larvae camiot extricate themselves 

 from the human skin or can do so only rarely. 



On beaches and other places, where hookworm-infected dogs and 

 cats have defecated and therefore contaminated the sand or soil with 

 the worm eggs, the larvae that issue from the eggs and metamorphose 

 by two successive molts to the infective stage, are attracted to the naked 

 human skin and penetrate it. Their subsequent migrations under its 

 subepithelial layer form the tortuous tunnels that characterize this 

 cutaneous disease. The intense irritation that the larval migrations 

 in the skin can cause leads to scratching of the affected areas. This, 

 in turn, aggravates the condition by causing these areas to become 

 inflamed. 



