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Divers carry pathogens in their wetsuits

May 25, 2006 By Helen Pearson This article courtesy of Nature News.

Better hygiene could squelch transfer of disease to corals.

Scuba divers could inadvertently be carrying coral disease from one reef to another, say scientists who have shown that bugs stick to wetsuits like glue. But a quick rinse in disinfectant can stop the spread.

Around 60% of the world's corals are thought to be under threat from warming seas, overfishing, pollution and coral diseases. Researchers have wondered whether ocean-hopping divers are playing a part by shipping disease-causing bacteria from an infected spot to a pristine one.

Diver and microbiologist Kay Marano-Briggs of George Mason University in Fairfax, Virginia, decided to investigate. She and her colleagues snipped swatches of material from wetsuits and bathed them in dilute solutions of bacteria for 30 minutes, the length of a typical dive. They then looked to see how many bugs had stuck.

The bacteria latch onto the wetsuits, the researchers found. This was true for Serratia marcescens and Vibrio carchariae, which are both thought to cause types of coral disease.

Dirty diving

The human pathogen Staphylococcus aureus proved equally tenacious. The researchers studied it because of reports that surfers were passing around the bugs from shared wetsuits. "I wouldn't want it on me," Marano-Briggs says.

The team then tested whether divers were likely to transport these bacteria from one dive to the next. After a dive, most divers leave their gear to dry out or give it a brief rinse in fresh water, so Marano-Briggs and colleagues mimicked this.

Vibrio carchariae actually multiplied after one hour's drying — the time it might take to travel by boat between dive spots. Drying for 18 hours or washing in tap water removed some, but not all of the bugs: rinsing cut the levels of S. marcescens, for example, by about 75%.

Soap solution

The good news is that the researchers found simple disinfection — as is done by some diving equipment rental shops — did kill the stubborn bacteria. A 5% solution of bleach wiped out almost all of them, as did a 7% solution of the household cleaner Lysol. The researchers presented their results at the meeting of the American Society for Microbiology in Orlando, Florida.

Marano–Briggs and her colleagues say that they still need to carry out more tests. They want to determine whether wetsuits really do pick up bacteria in the sea, for example, and whether the amount they collect is enough to cause a coral infection.

The results might make the case that areas infected with coral disease should be closed to divers, the researchers say. Perhaps "it would be reasonable to quarantine the area", Marano-Briggs suggests.

At the very least the scientists plan to come up with some guidelines for cleaning wetsuits. These could be promoted as best practice to divers, who are already taught not to touch or damage coral.

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