Armadas of bluebottle jellyfish have swarmed popular beaches in Australia, stinging more than 13,000 people in an “epidemic” caused by unusually strong winds.

Labelled an “invasion” by local media, the bluebottles have stung both swimmers in shallow water and those who accidentally trod on the creatures while walking on the sand.

The epicentre has been the popular beaches on the Gold Coast and the Sunshine Coast in the state of Queensland, but beaches in New South Wales, Victoria and Tasmania have also been affected.

Surf Life Saving Queensland said life guards had treated 13,243 bluebottle stings across the state in the past week and more than 18,000 since December 1. This was about triple the number of stings last year.

Jeremy Sturges, a spokesperson, said the “epidemic” had required the closure of several beaches.

“I have never seen anything like this - ever,” he told news.com.au.

“Not everyone reacts the same way but there have been very serious reactions.”

Bluebottles, sometimes known as the Indo-Pacific man-of-war, are a common sight at Australian beaches in summer and are often blown ashore or into shallow waters. Stings can be painful but are typically not dangerous, though some people can be allergic. No deaths have been confirmed from Australian species.