A randomized, controlled field trial for the prevention of jellyfish stings with a topical sting inhibitor

Abstract

Background: Jellyfish stings are a common occurrence among ocean goers worldwide with an estimated 150 million envenomations annually. Fatalities and hospitalizations occur annually, particularly in the Indo-Pacific regions. A new topical jellyfish sting inhibitor based on the mucous coating of the clown fish prevents 85% of jellyfish stings in laboratory settings. The field effectiveness is unknown. The objective is to evaluate the field efficacy of the jellyfish sting inhibitor, Safe Sea.

Methods: A double-blind, randomized, placebo-controlled trial occurred at the Dry Tortugas National Park, FL, USA and Sapodilla Cayes, Belize. Participants were healthy volunteers planning to snorkel for 30 to 45 minutes. Ten minutes prior to swimming, each participant was directly observed applying a blinded sample of Safe Sea (Nidaria Technology Ltd, Jordan Valley, Israel) to one side of their body and a blinded sample of Coppertone (Schering-Plough, Kenilworth, NJ, USA) to the contralateral side as placebo control. Masked 26 g samples of both Safe Sea SPF15 and Coppertone SPF15 were provided in identical containers to achieve 2 mg/cm(2) coverage. Sides were randomly chosen by participants. The incidence of jellyfish stings was the main outcome measure. This was assessed by participant interview and examination as subjects exited the water.

Results: A total of 82 observed water exposures occurred. Thirteen jellyfish stings occurred during the study period for a 16% incidence. Eleven jellyfish stings occurred with placebo, two with the sting inhibitor, resulting in a relative risk reduction of 82% (95% confidence interval: 21%-96%; p= 0.02). No seabather's eruption or side effects occurred.

Conclusions: Safe Sea is a topical barrier cream effective at preventing >80% jellyfish stings under real-world conditions.

Figures

Figure 1

Survey form.

Cercarial dermatitis, commonly known as swimmer’s itch, is caused by non-human Schistosoma specie larvae burrowing into the epidermis. An erythematous, papular eruption occurred 12 hours after snorkeling. The pruritic rash was present on the trunk and exposed skin with complete sparing under swimwear covered areas. Swimmer’s itch may occur either in salt or fresh water. The area of distribution of the dermatitis is in contrast to Seabather’s Eruption caused by envenomation by the larvae of thimble jellyfish which occurs under swimwear covered areas only in salt water. Submitted by Greta B. Chen MD