This 55 year old lady was swimming off the shore of Langkawi in October when she felt a severe stinging pain in her right arm. She just managed to swim back to shore and felt severe weakness and cold. She was admitted to hospital and antibiotics and parenteral support was started.
Her arm remained painful and cold and there was server spasm in the muscles. The pain was along the whole arm and was unremitting day and night. 3 days later, the hand began to swell and the thumb turned blue. She was able to move her fingers but could only just twitch her thumb.
The later part of the year is time time for Cnidaria species of aquatic stingers. This include the infamous Portuguese man of war and other "jelly fishes". The toxins they inject include neurotoxic toxins which causes neuropathic symptoms such as pain and paralysis. In addition, the necrotizing toxins causes muscle necrosis and fibrosis. Other toxins can cause hemolysis. The classical clinical picture is the typical "whip lash" marks on the surface of the skin. The skin may necrose as may the muscles. The neurtoxic element may take months to recover and may leave residual damage resulting in persistent pain. There are some databases on Cnidaria toxicity. The National University of Singapore has a database on toxins, but does not have much on Cnidaria toxicity. There are good databases in countries where this is a problem. The one that springs to mind is Australia where Box Jellyfishes and Portuguese man of war often poses a problem to swimmers.