Skin Patch May Stop Montezuma’s Revenge

Sept. 19, 2007 (Chicago) -- Researchers have developed a skin patch that prevents the curse of many trips abroad: travelers’ diarrhea.

In a study of more than 150 travelers to Mexico and Guatemala, the novel vaccine cut the risk of moderate to severe diarrhea by 75%. Those who did get sick had a shorter, milder course of illness, says researcher Herbert DuPont, MD, director of the Center for Infectious Diseases at the University of Texas School of Public Health in Houston.

The vaccine, which looks like a large bandage, goes on your arm or leg, he says.

“The idea of putting a Band-Aid on yourself and immunizing yourself when you travel is truly novel and exciting,” DuPont tells WebMD.

The research was presented at a meeting of the American Society for Microbiology.

17 Million Travelers Struck Each Year

Intestinal illness caused by contaminated food and drink is the most common malady afflicting international travelers, particularly in developing countries.

Seventeen million travelers are struck each year, typically suffering agonizing bouts of vomiting and diarrhea that last about three to five days, says Gregory Glenn, MD, chief scientific officer of Iomai Corp., which is developing the patch and funded the study.

The illness also raises the risk of developing irritable bowel syndrome, or IBS, a chronic disorder of the intestines that causes belly pain, cramping or bloating, and diarrhea or constipation by 10% to 30%, Glenn says.

“Travelers’ diarrhea is a bigger deal than we thought, causing this syndrome that can last for years, even decades,” DuPont says.

How It Works

He says that the patch contains a toxin that causes traveler’s diarrhea. Once it’s absorbed through the skin, the body makes antibodies against the toxin.

Then, if you eat food that contains the strain of E. coli bacterium that causes the diarrhea, the antibodies evoke an immune reaction that prevents the toxin from causing disease, DuPont explains.

The new study included 170 volunteers who put on two patches containing either the vaccine or a placebo, two to three weeks apart, with the second patch administered at least a week before travel.

The volunteers stayed in Mexico or Guatemala for at least five days, during which they kept detailed diaries and received checkups.

Risk of Severe Diarrhea Cut by 84%

Among the findings:

• Only 3 of 59 people who got the vaccine suffered moderate or severe diarrhea, compared with 23 of the 111 who received a placebo. This translates to a 75% reduction in risk.
• 1 of the 59 volunteers in the vaccine group reported severe diarrhea, compared with 12 of the 111 in the placebo group, an 84% reduction in risk.
• Of the vaccinated patients who did get sick, the diarrhea lasted only half a day on average. Those in the placebo group endured two days of illness.
• Three times as many people who got placebo developed IBS, compared with those who got the vaccine. But the numbers were so small they could have been due to chance.

There were no serious side effects.

The patch, which would be available by prescription only, is scheduled to undergo further testing, with FDA approval expected by 2011, DuPont says.

Randall Holmes, MD, PhD, chief of microbiology at the University of Colorado School of Medicine in Aurora, says the ease of administration is a real plus.

“There are no injections, which makes this very attractive,” he tells WebMD. Holmes is also developing a vaccine against travelers’ diarrhea, which would be administered orally. It’s in early development, he says.