Case 196. Cercarial dermatitis (45 y-o F)
    Itchy hemorrhagic vesiles of the legs formed along the water line of the rice field, recurrent for 6 years in the season of rice planting (biopsy)    
Key words : Gigantobilharzia sturniae, cercarial dermatitis
Hemorrhagic blisters of allergic nature are formed in both legs. This lady farmer has transplanted rice every year for 6 years.   A large subepidermal bulla is recognized histologically (HE). No cercaria is identified in the lesion.
Cercaria isolated from small snail, Polypylis nitidella, living in the rice field
The water snail is the intermediate host of the Schistosoma. Cercariae are released from the snail. Cercaria of the avian Schistosoma, Gigantobilaharzia sturniae, which parasitizes the bird "grey starling" provokes dermatitis at the site of skin invasion.
  Small freshwater snail, Polypylis nitidella, living in the rice field
Another type of cercarial dermatitis is caused by cercaria of Trichobilharzia brevis, which parasitizes mallard. Transmission was mediated by small snail, Austropeplea ollula. It is of note that skin lesions are hardly seen when cercariae of Schistosoma that parasitizes humans invade through the skin.
Reference case 196A
Another case of cercarial dermatitis, showing a clustered small papules at the ankle. They provoke itchy sensation. Cercarial dermatitis is seen worldwide. Original description was from the state of Michigan, USA.