An article in the much respected New England Journal of Medicine concluded that what happens when we travel far from home is that we encounter different strains of E. coli, an intestinal bacteria we all have with us. We get these bacteria because they are ubiquitous in the environment and they make us ill because they are new to us and we haven't formed antibodies against them yet. The proof is that some people moving to new parts of the world may be ill for a month or two, but finally everything normalizes.

I think it's pretty hard to beat good old Pepto Bismol, taken according to the directions on the bottle. It's available everywhere in the world without prescription and it works. It conveniently comes in tablets too. The only precaution is that it turns the stools black for a couple of days and that can be alarming to the unexpecting user. LoMotil tablets are available without prescription in Mexico and also are quite effective at slowing things down. Basically LoMotil is a narcotic with a mainly constipating effect.

Vomiting and diarrhea cause dehydration. Drinking water frequently and in small amounts is the best medicine for dehydration. The kidneys need to make about an ounce (30cc) of urine an hour to eliminate waste from the blood and that requires three 8-ounce drinking glasses of water per 24 hours. If you can't keep enough water down to achieve this urine output, hospitalization and intravenous fluids may be necessary.

If you want to be as safe as possible, eat only well-cooked foods, drink bottled drinks and stick to first-class restaurants. Eating food from stands on the street is a way you might get hepatitis, cholera, staphylococcal food poisoning, typhoid fever or other salmonella illnesses. These stands don't have hand washing facilities, running water, refrigeration or ways of disinfecting vegetables. The workers probably have no concept whatsoever of sanitation and you'll notice that everyone eats from the same unwashed plates. (www.oaxaca-reservations.com)