Patch guards against Montezuma’s revenge

From Philadelphia, at a meeting of the American Society of Tropical Medicine and Hygiene

A skin patch can prime the immune system to fend off traveler’s diarrhea, a test shows.

Bacteria that contaminate food and water in developing countries cause roughly 17 million cases of diarrhea each year, many in visitors to those countries. To test a vaccine against a strain of Escherichia coli responsible for a large fraction of these bouts, researchers enlisted U.S. volunteers who were planning travel to Mexico or Guatemala. Shortly before each traveler’s departure, the scientists mildly abraded a small area of each person’s skin and then applied a patch. One-third got the vaccine; the others received an inert patch.

During roughly 2 weeks of travel, 170 participants kept diaries of their health. Five percent of those getting the vaccine patch and 21 percent of those getting the placebo reported a moderate or severe case of diarrhea on their trips, reports Gregory M. Glenn of Iomai Corp. in Gaithersburg, Md., which makes the vaccine.

The patch contains a toxin made by the bacterium. In many people, exposure through the skin appears to be enough to induce an immune response without causing disease, Glenn says.

“This is an area where we’ve had really few breakthroughs in past years,” he says.