Vaccine Skin Patch Prevents Montezuma's revenge

A new skin patch containing E. coli toxins seems to help prevent travelers' diarrhea, researchers report.

Even when people developed diarrhea, the condition was less severe and the agonizing episode shorter, they added.

Consuming E. coli from contaminated food or drink is the main cause of travelers' diarrhea, which affects some 27 million adult travelers and 210 million children each year. The disease is responsible for some 380,000 child deaths. Travelers' diarrhea usually lasts four to five days, and is associated with nausea, vomiting, abdominal cramps and dehydration.

"When people travel to Guatemala or Mexico, they have a 50 percent chance of having a bout of Montezuma's revenge," said Dr. Gregory Glenn, the head of IOMAI Corp., the Maryland company that developed the patch. "To date, there is no vaccine for this. People with the condition go to bed and are treated with antibiotics."

"This is really a big breakthrough," Glenn said. "For an infectious disease, this has been an extremely challenging area."

To be effective, two doses of the vaccine are needed, Glenn said. The vaccine takes advantage of the skin's potent immune system, which gives the vaccine its robust response, he added.

The vaccine is most effective when given two weeks before one travels abroad, Glenn said.

The report is published in the June 12 online issue of The Lancet.

In this phase II trial, 178 people planning trips to Mexico or Guatemala were randomly assigned to the vaccine patch or placebo patches.

Glenn and his study co-author, Dr. Herbert DuPont of the University of Texas School of Public Health in Houston, found that 24 of the 111 travelers who received placebo had travelers diarrhea, of these 11 had diarrhea caused by E. coli. Among the 59 travelers who received the vaccine, 12 had bouts of diarrhea, but only three had diarrhea caused by E. coli.

Among patients who received placebo, the rate of moderate to severe diarrhea was higher (21 percent) than among people who received the vaccine (5 percent). This means the patch was 75 percent effective for people who had moderate to severe diarrhea.

Moreover, the number of cases of severe diarrhea was higher amongst people who received placebo (11 percent), compared with those who received the vaccine (2 percent), Glenn's group found. Among these patients, the patch was effective 84 percent of the time.

In addition, people who received the vaccine had shorter episodes of diarrhea -- half a day, compared with more than two days for people who received the placebo patch.

The vaccine is delivered by a patch, because the active ingredient is too toxic to be delivered orally, nasally, or by injection, the researchers noted.

The vaccine still needs to go through a large, phase III trial, Glenn noted. He is hoping the vaccine will be available to the public by 2011.

One expert thinks the patch could be an important advance in preventing travelers' diarrhea.

"This is an important advance in the prevention of travelers' diarrhea. The vaccine is easy to store and administer, and is very well-tolerated," said Dr. Pablo C. Okhuysen, an associate professor of medicine in the Division of Infectious Diseases at The University of Texas Medical School at Houston. "The patch vaccine approach is novel and opens the door for the future development of vaccines for the prevention of diarrheal disease." - ajc