It might be called MSDS or Mysterious Swimmer's Death Syndrome. For a number of years, swimmers and divers died mysteriously after swimming in waters around Queensland Australia.
They often experienced nausea, cramps and excruciating pain in their torso and extremities. Some deaths occurred within hours and were thought to be heart attacks. One reason is because a number of mysterious injuries seem similar to stings from box jellyfish, yet the swimming areas have been protected by "sting nets".
But marine biologists believe the mysterious injuries and deaths resulted from the sting of a previously unknown tiny jellyfish. The creatures are transparent and so small they can swim through "sting nets".
Enter Irukandji, named after an aboriginal tribe of Cairns. The tiny cousin of the box jellyfish aka "sea wasp" packs a more powerful sting than the much larger species.
Irukandji stings can kill within hours. The toxins from the sting barbs enter the bloodstream after about 20 minutes. Due to this delay, many victims don't associate the nausea with jellyfish since the initial sting is quite mild.
At present there is no antidote for the Irukandji sting.
The pain following an Irukandji sting is so intense that the maximum dose of morphine is not totally effective. The victim's blood pressure doubles, putting extreme stress on the body's vascular system. Extreme pain, nausea & vomiting; and cramps may last for days even with expert medical care. Recovery may require weeks
Divers should be especially careful on night dives since Irukandji is attracted to light.
Irukandji are more commonly found in calm and warm waters in very hot conditions.
Australia may be where the Irukandji originated, but the tiny creature swims rather than drifts. That means it may be found in other areas. It is known to exist around Palau.
Complete "sting suits" are the only complete protection from the Irukandji.