HOUSTON -- South of the border is a popular destination for many Americans. But some end up spending their vacation in bed after they come down with what's known as Montezuma's revenge.

"People who get diarrhea are decked for about a day," said Dr. Herbert DuPont, chief of internal medicine at St. Luke's Hospital in Houston.

While many avoid the water in Mexico, salsa may be to blame, DuPont said.

"We found almost half of all the hot sauces in Mexico had this disease-causing bacteria," he said. "The hot sauces sit around on the table tops all day long and they get contaminated."

E. coli is a microscopic bug that can cause huge stomach problems. It has been proved to swell and inflame an animal's intestine.

"It causes pain because the stretching of the intestine causes pain," DuPont said.

Approximately 30 million travelers come down with the bug each year. It can be embarrassing and painful.

A tiny new pill is proving to be a traveler's best defense, reported KPRC-TV in Houston. It's called Xifaxan. It was recently approved by the Food and Drug Administration and is available by prescription.

There are a few side effects, but doctors say a daily dose can prevent Montezuma's revenge.

Liliana Rodriguez, a microbiologist, knows just how painful Montezuma's revenge can be -- she's had it.

"It's debilitating," she said. "You have horrible abdominal cramps and then you have this profuse, watery diarrhea that's debilitating."

In addition to putting a stop to traveler's diarrhea, Xifaxan might also come in handy in more serious situations -- like a foodborne bioterrorism attack.

"The shigella is a form of foodborne bacteria that probably would be the one that would be picked (for an attack)," DuPont said.

Xifaxan could be the best defense against shigella, said DuPont, who is a member of a government panel on bioterrorism.

More Information: Xifaxan