Strongyloides stercoralis. The cause of an urticarial-like eruption of 65 years' duration.

A 74-year-old woman with a history since childhood of skin eruptions and gastrointestinal problems was found to have peripheral eosinophilia. This finding was subsequently related to a chronic infection with the parasite Strongyloides stercoralis. This parasite is capable of autoinfection, which would account for the infection persisting for about 65 years. The intraduodenal habitat of S stercoralis and the negative results of numerous stool examinations promoted the use of the duodenal string test, which was diagnostic. A high index of suspicion should exist for patients from endemic regions in Southeast Asia and the Southeastern United States.