Maggots help clean out leg wounds but don't lead to faster healing compared with gels that are easier to use, a trial suggests.

In Friday's online issue of the British Medical Journal, researchers compared use of maggots — the larvae of blowflies — to the standard pharmaceutical treatment for chronic leg ulcers caused by poor blood circulation.

Maggots were first used to treat wounds about 700 years ago, since the insect larvae eat only dead and rotting tissue without burrowing into healthy flesh.

But British researchers said this was the first randomized clinical trial to investigate the clinical benefits of the natural approach. A separate analysis calculated the cost-effectiveness of the two therapies.

The trial involved 267 people who had at least one venous leg ulcer with dead tissue covering at least a quarter of the wound. Participants were randomly assigned to receive either maggots or hydrogel.

The maggots were bred in sterile conditions and were about the size of a grain of rice. The insects were applied either in teabag-sized packets or directly into the wound with bandages.

Maggot therapy significantly reduced the time for debriding, or removing dead tissue, from wounds compared with hydrogel. But there was no significant difference in how long it took for the ulcer to heal, the researchers found.

'Hoovering up goo'

Half the people in the maggot group healed in 236 days, compared with 245 days for the hydrogel group.

All participants were questioned when the study began and then again at three, six, nine and 12 months.

Those whose wounds were treated with maggots reported more pain in the 24 hours before the first application was removed compared with hydrogel.

The pain may have been due to enzymes secreted by the insects, said study author Nicky Cullum, a professor at the University of York.

"They're not chomping down with big teeth or anything," said Cullum. "They're just hoovering up goo."

Role for insects

Christine Pearson, a community wound clinician for Vancouver Coastal Health, said she was surprised by the U.K. trial's findings.

"It's not similar to my experiences," said Pearson, a registered nurse who has long used maggot therapy. "In my practice, I've found that getting rid of the slough is better in most cases. If you leave the slough in the wound, we find that it's a good source for bacteria to thrive on."

"Contrary to what they're saying, we would find that people were healing faster."

The cost effectiveness of both approaches were similar, the authors of a second study concluded.

Maggots could be better for some specialized cases, such as preparing patients for skin grafts, where faster wound cleaning means patients can be moved into surgery more quickly, but that idea still needs to be formally tested.

Sometimes surgical debridement is best, said Dr. Gary Sibbald, director of the wound healing clinic at Women's College Hospital in Toronto.

Maggot treatment could be useful for nurses whose scope of practice does not include a surgical option, added Sibbald, who doesn't use the therapy in his work.

With files from the Associated Press, the Canadian Press