By Maggie Fox, Health and Science Editor
WASHINGTON, June 11 (Reuters) - A needle-free vaccine protected more than 70 percent of visitors to Mexico and Guatemala from traveler's diarrhea, popularly known as Montezuma's Revenge, researchers reported on Wednesday.
Even if travelers did get infected with the stomach bug, Iomai Corp.'s IOMI.O experimental vaccine patch prevented severe illness, the researchers reported in the Lancet medical journal.
"I think it's one of the most exciting new developments in travel medicine," said Dr. Herbert DuPont of the University of Texas in Houston, who helped test the vaccine.
"People could buy this and put it on themselves whenever they take a trip. It is the most convenient form of immunization I have ever seen," DuPont said in a telephone interview.
The vaccine protects against Escherichia coli bacteria -- specifically a strain known as Enterotoxigenic E. coli or ETEC.
It is the leading cause of diarrhea in travelers to certain areas, causing four to five days of misery including nausea and cramps.
Iomai's team, along with DuPont's independent team and a group at Johns Hopkins University in Baltimore, tested the patches in a Phase II safety and efficacy trial. They got data back from 170 adults traveling to areas known to be hot spots of tummy trouble in Guatemala and Mexico.
'AMONG THE BEST WE HAVE'
During and after travel, 15 percent of the patients who got the vaccine developed diarrhea of any type, and just 5 percent had ETEC-associated diarrhea. This compared to 22 percent of travelers who got placebo, 10 percent of whom had ETEC diarrhea.
Eleven percent of the travelers who got placebo had severe diarrhea, compared to 2 percent of those who got the patch.
"It looked like it prevented more than 70 percent of the episodes of moderate or severe traveler's diarrhea," DuPont said. "This vaccine is among the best we have for these kinds of diseases."
The vaccine also appeared to protect against non-ETEC causes of diarrhea. DuPont said it may stabilize the intestine and prevent the reaction to infection that causes diarrhea.
Austrian vaccine maker Intercell ICEL.VI is in the process of buying Maryland-based Iomai, which also has a patch that boosts the effects of influenza vaccines.
DuPont, who said he receives no payments from Iomai, said the market potential could be large because "we have no vaccine for traveler's diarrhea."
The needle-free approach could work against other infectious diseases, he said.
The company plans a Phase III trial of the vaccine -- the last stage of testing before seeking U.S. Food and Drug Administration approval. (Editing by Will Dunham and Xavier Briand)