Cercarial Dermatitis

Cercarial dermatitis (swimmer's itch) is an acute cutaneous inflammatory response caused by the penetration of cercaria of nonhuman schistosomes. It frequently presents with itchy erythematous papules, which cover the water-exposed areas within 24 hours. This paper reports a case of cercarial dermatitis in a 60-year-old man who presented with itchy erythematous papules on bilateral lower legs after walking upstream in the Mu-Gua River in Hualien. His symptoms and signs could not be relieved by treatment with topical steroids and a skin biopsy was performed. Skin pathology revealed massive eosinophil infiltration of the dermis and fragments of larvae perpendicular to the skin surface. Based on the history, clinical course and the shape, length and penetration of the larvae, which was revealed by the skin pathology, cercarial dermatitis was diagnosed. His symptoms were relieved spontaneously 3 weeks after infection. [Tzu Chi Med J 2008;20(1):63–66]