Probable Irukandji-Like Syndrome in the US Florida Keys

Sixteen of the world’s 50 known species of box jellyfish are associated with Irukandji syndrome, which involves a multitude of delayed reactionary and potentially life-threatening symptoms. The most common species associated with Irukandji syndrome is Carukia barnesi ( C. barnesi ), a very small member of the Carybdeid family. These box jellyfish are native to Australian waters, where most cases of Irukandji syndrome occur. However, cases of Irukandji-like syndrome have been reported worldwide after envenomation by species other than C. barnesi , including non-Carybdeid jellyfish. Herein, we report a probable new case of Irukandji-like syndrome in the US Florida Keys, a region where C. barnesi has not been recorded. Although it is unclear exactly which jellyfish are the causal organisms, a clustering of four incidents in the western Florida Keys suggests that jellyfish other than C. barnesi , or possibly non-Carybdeid jellyfish, are causing Irukandji-like syndromes in this area.