A Canadian tourist spent 16 days in a New Zealand hospital after a poisonous katipo spider bit him on the penis.
The 22-year-old had gone skinny-dipping on a beach in Northland earlier this year, leaving his clothes on the sand dunes.
The New Zealand Medical Journal says he woke from a post-swim nap to find his penis swollen and painful, with a red mark which suggested that he had been bitten.
It says the man rapidly developed generalised muscle pains, fever, headache, photophobia and vomiting.
The diagnosis of a spider bite was made 36 hours after the incident and anti-venom given to the man.
The Canadian subsequently developed severe inflammation of the heart muscle, which the New Zealand Medical Journal reports is the first time this is known to have happened after a katipo bite.
The tourist has since left New Zealand.