A short-lived rash that occurs as an allergic reaction to larval (cercariae) infection of the skin. These particular parasites use birds and animals as their first hosts. Larval eggs are excreted in the faeces and when they land in water, they hatch into larvae which then infect certain aquatic snails. The infected snails release another form of the larvae called cercariae which then search for a bird, mammal host. When they enter the skin of a human they die as humans are unsuitable hosts but the skin can produce an allergic reaction. See also Cercarial dermatitis