"A lot is happening these days, both in therapy and prevention and determining who gets sick," said Dr. Herbert DuPont, who has studied traveler's diarrhea for 30 years as director of travel medicine at St. Luke's Hospital in Houston.
DuPont remains a firm believer in the food-safety guidelines. The problem, he says, is that not enough people know them — and follow them.
"I'm very careful about what I eat, and I never get sick," said DuPont, who sometimes carries a thermometer to make sure his food is hot enough.
The careful approach has worked well for Bettina Shell-Duncan, a University of Washington anthropology and health-services professor who studies women's and children's health in northern Kenya. Living among nomadic people who have several words in their language for diarrhea, Shell-Duncan was able to keep herself healthy by filtering her water, preparing her own food and sticking to well-cooked dishes when she ate in restaurants.
She only got nailed during a holiday on the coast, when she let her guard down.
"I bought some fruit from a street vendor — cut up papaya slices," she said. "I can't be certain that was the cause, but I think I paid a price for it."
For most tourists, cooking isn't an option and eating out is part of the adventure — which makes it hard to adhere to a strict regimen like DuPont's.
"People don't want to follow these draconian rules of things to avoid, where you're watching every piece of food you put in your mouth," said Dr. David Taylor, of Johns Hopkins School of Public Health. "Vacations are supposed to be fun."
Several studies have found that few tourists successfully avoid all high-risk foods. A recent survey of visitors to Peru found less than 2 percent followed the rules scrupulously — and 25 percent got sick.
Shlim agrees compliance is low, but says the studies also show no correlation between the number of lapses and the risk of getting diarrhea, which raises questions about how effective the rules really are.
Still, experts recommend travelers stick to the guidelines as much as possible — and arm themselves with antibiotics just in case.
"My feeling is that you can bring down your risk somewhat by taking basic precautions," said Dr. Christopher Sanford, director of the Hall Health Travel Clinic at the University of Washington. "But I don't think you can bring the risk down to zero."
Jet lag exonerated
The real revolution in treating traveler's diarrhea came in the mid-1980s, with the discovery that bacterial contamination is responsible for up to 80 percent of cases. Before that, experts blamed jet lag or the biological shock of an unfamiliar environment.
What to eat
Generally safe:
• Very hot (temperature-wise) foods
• Dry food, like bread
• Bottled water
• Beer, bottled and canned beverages, hot coffee and tea
• Citrus fruit and other acidic foods
• Fruits and vegetables you peel yourself
Generally unsafe:
• Tap water, juices and other drinks made with tap water
• Lukewarm food, as from buffets or steam tables
• Raw or undercooked meat or seafood
• Unpeeled fruits and vegetables
• Unpasteurized milk and dairy products
Source: Herbert DuPont; CDC
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Sulfa drugs were among the earliest antibiotics used to treat traveler's diarrhea, but they became useless after bacteria developed resistance. Today's drugs of choice are Cipro and related drugs, called fluoroquinolones.
Quick treatment with Cipro can cut the course of traveler's diarrhea from the normal five to seven days to as little as 12 to 24 hours, Sanford said.
But some bugs, particularly in Thailand and Southeast Asia, are becoming impervious to Cipro.
Seattle resident Jeff Bates got hit by one of those resistant strains during a recent trip to India and Pakistan, where he was part of a World Health Organization program to eradicate the pockets of polio infection.
When he first got sick, he took a fluoroquinolone, with no effect.
The malaise lingered for more than six weeks. Only after returning to the U.S., where he got a short course of an antibiotic called Azithromycin, did the bug clear up.
As he gets ready to return to Pakistan, Bates said he believes it's better to be prepared with drugs than to agonize over food choices.
"It pays to keep an eye on things, but in some places you just can't avoid the contamination."
People like Bates, who spend months or more in another country, will eventually develop immunity to most diarrhea-causing microorganisms. But it can take several years for full protection to kick in.
Doctors would love to have a drug to prevent traveler's diarrhea, rather than treat it after the fact. A daily dose of Cipro is highly effective, but doctors are reluctant to prescribe it preventively because of side effects, including rashes — and even diarrhea. They also worry widespread use will accelerate the spread of resistant bacteria.
New drug in pipeline
In his Texas lab, DuPont has been testing a new antibiotic, Rifaximin, which may gain FDA approval next year. Already used in 15 other countries, the drug stays in the digestive tract, which means it has fewer side effects than systemic drugs such as Cipro. In preliminary trials, it worked as well as Cipro for knocking out traveler's diarrhea, DuPont said.
Most exciting, though, is the possibility Rifaximin will prove safe enough to become the long-sought preventative, said DuPont, who conducts research for the drug's manufacturer, but has no other financial stake in the product.
The Texas researcher has also uncovered evidence of a genetic basis for iron stomachs and delicate digestion. In a small study of volunteers in Guadalajara, Mexico, nearly 90 percent of those who got sick had a gene variation that cranks up inflammation in the gut. Most of those who didn't get sick — even though they were infected with the same bug — lacked the gene variation.
Someday, DuPont predicted, it will be possible to identify people who are most sensitive to traveler's diarrhea and give them a drug to prevent it.
"It's an exciting time in this field." |
