Every winter since I've been in France, like clockwork, there is an épidémie de gastro ("stomach flu"). People disappear for days at a time and reappear looking pale and exhausted. Children are especially susceptible. La gastro can hide more severe problems. A 13-year-old girl I know recently had to have her appendix removed in an emergency operation-- her family had thought her bad stomach-aches were caused by the usual gastro.
In France, it's not usually a serious disease, of course. But in Africa, it still kills millions of people a year. One of its major causes is not washing your hands, and it's hard to if you don't have access to clean water.
I've never had it. My family doesn't seem to get it. I don't think it's because we're more resistant, but just because we wash our hands more. (My mother was a public-health nurse.) I'm always astonished in public bathrooms here by how few people wash their hands. I have even met people who say they don't because it makes them stronger; when they go to India or Africa, they don't get sick!
Americans are not so wonderful at hand-washing either. The number four cause of death in the U.S.A. every year is hospital-acquired infection, which can be almost completely prevented when hospital health-care workers wash their hands properly. But study after study shows that only about half do.
It's winter, and la gastro is back again. In the past three weeks more than half a million people in France have consulted a doctor about it. The average age of those who get sick is 24. Wash your hands!