The New Zealand Scaup duck. A small black duck with yellow eyes and a grey bill swims in a lake near Christchurch.

Swimmer’s itch and duck itch in the Southern Lakes 

Have you ever gone home after a swim and later found you’re covered in small, very itchy red dots? That could be duck itch – also known as swimmer’s itch, or schistosome cercarial dermatitis.  What is duck itch and swimmer’s itch? Duck itch is caused by an allergic reaction to the cercariae (larvae) of schistosomes …