"It didn't completely inhibit the stings, but it came pretty darn close," reported Alexa Kimball, MD, MPH, an assistant professor of dermatology who directed the study. The study appears in the June issue of the journal Wilderness and Environmental Medicine.
The Stanford researchers borrowed sea nettles from the Monterey Bay Aquarium to do the testing on volunteers in a research clinic at Stanford Hospital. These nettles are known to sting swimmers, surfers and boaters worldwide, including along the Chesapeake Bay and the coastlines of Florida and California. Their stings cause a burning sensation, as well as swelling, pain and occasional blisters.
Study collaborators at the Bert Fish Medical Center in Florida also tested a more dangerous species known as the box jellyfish or sea wasp, which is prevalent along the Florida and Texas coasts and around the Gulf of Mexico. The stings from these jellyfish can cause severe reactions and can be life-threatening, particularly in young children.
The two portions of the study involved a total of 24 volunteers who had one arm smeared with the sting-inhibiting cream, which also contains sunscreen, and the other arm with a commercial sunscreen alone. The researchers took wet jellyfish tentacles stored in tanks and placed them on the forearms of the volunteers for up to 45 seconds. The tentacles contain nematocysts, a group of nasty little cells that can eject a toxin-carrying harpoon in a fraction of a second. Kimball said the researchers had no difficulty finding willing subjects for the testing, as many were surfers or others who had been stung before and wanted to find a way to protect themselves against future injury.
She and her fellow dermatologists examined the volunteers' arms after exposure to the tentacles, not knowing which arm had been coated with the inhibitor cream and which had sunscreen alone.
Among the 12 volunteers exposed to the Monterey Bay nettles, they found no visible changes in the arms treated with the sting inhibitor, though two participants did report mild discomfort. Of the arms smeared with sunscreen only, all 12 showed swelling and the volunteers reported discomfort, the researchers reported.
As for the group exposed to the more dangerous box jellyfish, three of the 12 treated with the sting inhibitor reported discomfort, compared with 10 in the untreated group. Only one inhibitor-treated arm had visible signs of a sting, compared to nine of those coated with sunscreen only.
"This certainly suggests the cream is going to help," said Kimball, who is director of clinical trials in dermatology. "Even if it doesn't offer 100-percent protection, I would rather have some protection over none."
The ingredients of the cream are proprietary, but Kimball said she believes the inhibitor works in several ways. For one, it naturally repels water, making it difficult for the jellyfish to make contact with the skin, she said. It also contains a mixture of sugar and protein that is similar to a substance found in the jellyfish bell. Jellyfish use their bells as a recognition system, so that when the creature comes into contact with the substance, it thinks it's found itself instead of some tempting human flesh. Finally, the cream is believed to disrupt the jellyfish's communication system so that it doesn't get the signal to release its venom, she said.
Kimball said the study doesn't settle the question of whether the cream works in open water, though anecdotal evidence suggests it might.
Paul Auerbach, MD, former chief of emergency medicine at Stanford and one of the researchers, said he initially tried the cream about five years ago by smearing some on half of his neck and then jumping into the Mexican ocean awash in thimble jellyfish.
"The side I painted had two little red bumps on it, and the side I didn't paint looked like a road map of Florida. That's what convinced me we should do the studies," said Auerbach, now a member of the adjunct clinical faculty. Auerbach became a consultant to the company, Nidaria Technology, which makes the cream, marketed as SafeSea.
The study also doesn't indicate how long the cream might remain effective during water activities. Auerbach recommends reapplication every 45 to 60 minutes in relatively calm waters or, in heavy surf, every 30 to 45 minutes.
Other collaborators on the study are Karina Zuelma Arambula, Michael Liu, MD, and Wingfield Ellis Rehmus, MD, MPH, of Stanford; Arlen Ray Stauffer, MD, Valey Levy, MD and Valerie Weaver Davis, MD of the Bert Fish Medical Center; and Amit Lotan of Nidaria Technology in Israel.
The research was funded in part by a grant from Nidaria Technology.
Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford. For more information, please visit the Web site of the medical center's Office of Communication & Public Affairs at http://mednews.stanford.edu.
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Journal
Wilderness and Environmental Medicine